ZincFrom Wikipedia, the free encyclopedia

This article is about the metallic element. For other uses, see Zinc (disambiguation).

Zinc

30Zn

-↑Zn↓Cd

Periodic table

copper ← zinc → gallium

Appearance

silver-gray

General properties

Name, symbol,number zinc, Zn, 30

Pronunciation / ̍ z ɪ ŋ k /  ZINGK

Element category transition metal

alternatively considered a post-transition

metal

Group, period,block 12, 4, d

Standard atomic weight 65.38(2)

Electron configuration [Ar] 3d10 4s2

2, 8, 18, 2

History

Discovery Indian metallurgists(before 1000 BC)

First isolation Andreas Sigismund Marggraf(1746)

Recognized as a

unique metal by

Rasaratna Samuccaya (800)

Physical properties

Phase solid

Density (nearr.t.) 7.14 g·cm−3

Liquid density atm.p. 6.57 g·cm−3

Melting point 692.68 K, 419.53 °C, 787.15 °F

Boiling point 1180 K, 907 °C, 1665 °F

Heat of fusion 7.32 kJ·mol −1

Heat of vaporization 123.6 kJ·mol−1

Molar heat capacity 25.470 J·mol−1·K−1

Vapor pressure

P (Pa) 1 10 100 1 k 10 k 100 k

at T (K) 610 670 750 852 990 1179

Atomic properties

Oxidation states +2, +1, 0

(amphoteric oxide)

Electronegativity 1.65 (Pauling scale)

Ionization energies

(more)

1st: 906.4 kJ·mol−1

2nd: 1733.3 kJ·mol−1

3rd: 3833 kJ·mol−1

Atomic radius 134 pm

Covalent radius 122±4 pm

Van der Waals radius 139 pm

Miscellanea

Crystal structure hexagonal close-packed

Magnetic ordering diamagnetic

Electrical resistivity (20 °C) 59.0 nΩ·m

Thermal conductivity 116 W·m−1·K−1

Thermal expansion (25 °C) 30.2 µm·m−1·K−1

Speed of sound(thin rod) (r.t . ) (rolled) 3850 m·s−1

Young's modulus 108 GPa

Shear modulus 43 GPa

Bulk modulus 70 GPa

Poisson ratio 0.25

Mohs hardness 2.5

Brinell hardness 412 MPa

CAS registry number 7440-66-6

Most stable isotopes

Main article: Isotopes of zinc

iso NA half-life DM DE (MeV) DP

64Zn 48.6% >2.3×10 18  y β + β + 1.096 64Ni

65Zn syn 243.8 d ε 1.3519 65Cu

γ 1.1155 -

66Zn 27.9% 66Zn is stable with 36 neutrons

67Zn 4.1% 67Zn is stable with 37 neutrons

68Zn 18.8% 68Zn is stable with 38 neutrons

69Zn syn 56 min β − 0.906 69Ga

69mZn syn 13.76 h β − 0.906 69Ga

70Zn 0.6% >1.3×10 16  y β − β − 0.998 70Ge

71Zn syn 2.4 min β − 2.82 71Ga

71mZn syn 3.97 d β − 2.82 71Ga

72Zn syn 46.5 h β − 0.458 72Ga

V

 

T

 

E

 

· r

Zinc, in commerce also spelter, is a metallic chemical element; it has the symbol Zn and atomic number 30. It

is the first element of group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium,

because its ion is of similar size and its only common oxidation state is +2. Zinc is the 24th most abundant

element in the Earth's crust and has five stable isotopes. The most common zinc ore is sphalerite (zinc blende),

a zinc sulfide mineral. The largest mineable amounts are found in Australia, Asia, and the United States. Zinc

production includes froth flotation of the ore, roasting, and final extraction using electricity (electrowinning).

Brass, which is an alloy of copper and zinc, has been used since at least the 10th century BC. Impure zinc

metal was not produced in large scale until the 13th century in India, while the metal was unknown to Europe

until the end of the 16th century. Alchemists burned zinc in air to form what they called "philosopher's wool" or

"white snow."

The element was probably named by the alchemist Paracelsus after the German word Zinke. German

chemist Andreas Sigismund Marggraf is normally given credit for discovering pure metallic zinc in 1746. Work

by Luigi Galvani and Alessandro Volta uncovered the electrochemical properties of zinc by 1800. Corrosion-

resistant zinc plating of iron (hot-dip galvanizing) is the major application for zinc. Other applications are

inbatteries, small non-structural castings, and alloys, such as brass. A variety of zinc compounds are commonly

used, such as zinc carbonate andzinc gluconate (as dietary supplements), zinc chloride (in deodorants), zinc

pyrithione (anti-dandruff shampoos), zinc sulfide (in luminescent paints), and zinc methyl or zinc diethyl in the

organic laboratory.

Zinc is an essential mineral of "exceptional biologic and public health importance".[1] Zinc deficiency affects

about two billion people in the developing world and is associated with many diseases.[2] In children it causes

growth retardation, delayed sexual maturation, infection susceptibility, and diarrhea, contributing to the death of

about 800,000 children worldwide per year.[1] Enzymes with a zinc atom in the reactive center are widespread

in biochemistry, such as alcohol dehydrogenase in humans. Consumption of excess zinc can

cause ataxia, lethargy andcopper deficiency.

Contents

  [hide] 

1 Characteristics

o 1.1 Physical properties

o 1.2 Occurrence

o 1.3 Isotopes

2 Compounds and chemistry

o 2.1 Reactivity

o 2.2 Zinc(I) compounds

o 2.3 Zinc (II) compounds

3 History

o 3.1 Ancient use

o 3.2 Early studies and naming

o 3.3 Isolation

o 3.4 Later work

4 Production

o 4.1 Mining and processing

o 4.2 Environmental impact

5 Applications

o 5.1 Anti-corrosion and batteries

o 5.2 Alloys

o 5.3 Other industrial uses

o 5.4 Dietary supplement

o 5.5 Topical use

o 5.6 Organic chemistry

6 Biological role

o 6.1 Enzymes

o 6.2 Other proteins

o 6.3 Dietary intake

o 6.4 Deficiency

o 6.5 Dreaming

6.5.1 Argriculture

7 Precautions

o 7.1 Toxicity

o 7.2 Poisoning

8 See also

9 Notes

10 References

11 Bibliography

12 External links

Characteristics

Physical properties

Zinc, also referred to in nonscientific contexts as spelter,[3] is a bluish-white, lustrous, diamagnetic metal,

[4] though most common commercial grades of the metal have a dull finish.[5] It is somewhat less dense

than iron and has a hexagonal crystal structure.[6]

The metal is hard and brittle at most temperatures but becomes malleable between 100 and 150 °C.[4][5] Above

210 °C, the metal becomes brittle again and can be pulverized by beating.[7] Zinc is a fair conductor of

electricity.[4] For a metal, zinc has relatively low melting (419.5 °C, 787.1 F) and boiling points (907 °C).[8] Its

melting point is the lowest of all the transition metals aside from mercury and cadmium.[8]

Many alloys contain zinc, including brass, an alloy of copper and zinc. Other metals long known to form binary

alloys with zinc are aluminium,antimony, bismuth, gold,

iron, lead, mercury, silver, tin, magnesium, cobalt, nickel, tellurium and sodium.[9] While neither zinc

nor zirconium areferromagnetic, their alloy ZrZn2 exhibits ferromagnetism below 35 K.[4]

Occurrence

See also: Zinc minerals

Zinc makes up about 75 ppm (0.0075%) of the Earth's crust, making it the 24th most abundant element. Soil

contains 5–770 ppm of zinc with an average of 64 ppm. Seawater has only 30 ppb zinc and the atmosphere

contains 0.1–4 µg/m3.[10]

Sphalerite (ZnS)

The element is normally found in association with other base metals such as copper and lead in ores.[11] Zinc is

achalcophile, meaning the element has a low affinity for oxides and prefers to bond with sulfides. Chalcophiles

formed as the crust solidified under the reducing conditions of the early Earth's atmosphere.[12] Sphalerite,

which is a form of zinc sulfide, is the most heavily mined zinc-containing ore because its concentrate contains

60–62% zinc.[11]

Other minerals from which zinc is extracted

include smithsonite (zinc carbonate), hemimorphite (zinc silicate),wurtzite (another zinc sulfide), and

sometimes hydrozincite (basic zinc carbonate).[13] With the exception of wurtzite, all these other minerals were

formed as a result of weathering processes on the primordial zinc sulfides.[12]

Identified world zinc resources total about 1.9 billion tonnes.[14] Large deposits are in Australia, Canada and the

United States with the largest reserves in Iran.[12][15][16] At the current rate of consumption, these reserves are

estimated to be depleted sometime between 2027 and 2055.[17][18] About 346 million tonnes have been

extracted throughout history to 2002, and one estimate found that about 109 million tonnes of that remains in

use.[19]

Isotopes

Main article: Isotopes of zinc

Five isotopes of zinc occur in nature. 64Zn is the most abundant isotope (48.63% natural abundance).[20] This

isotope has such a long half-life, at4.3×1018 a,[21] that its radioactivity can be ignored.[22] Similarly, 70Zn (0.6%),

with a half-life of 1.3×1016 a is not usually considered to be radioactive. The other isotopes found in nature

are 66Zn (28%), 67Zn (4%) and 68Zn (19%).

Several dozen radioisotopes have been characterized. 65Zn, which has a half-life of 243.66 days, is the most

long-lived radioisotope, followed by 72Znwith a half-life of 46.5 hours.[20] Zinc has 10 nuclear isomers. 69mZn has

the longest half-life, 13.76 h.[20] The superscript m indicates a metastableisotope. The nucleus of a metastable

isotope is in an excited state and will return to the ground state by emitting a photon in the form of a gamma

ray. 61Zn has three excited states and 73Zn has two.[23] The isotopes 65Zn, 71Zn, 77Zn and 78Zn each have only

one excited state.[20]

The most common decay mode of a radioisotope of zinc with a mass number lower than 66 is electron capture.

The decay product resulting from electron capture is an isotope of copper.[20]

n

30Zn + e− → n

29Cu

The most common decay mode of a radioisotope of zinc with mass number higher than 66 is beta

decay (β–), which produces an isotope ofgallium.[20]

n

30Zn → n

31Ga + e− + ν

e

Compounds and chemistry

Main article: Compounds of zinc

Reactivity

Zinc has an electron configuration of [Ar]3d104s2 and is a member of the group 12 of the periodic table.

It is a moderately reactive metal and strong reducing agent.[24] The surface of the pure

metal tarnishes quickly, eventually forming a protective passivating layer of the basic zinc

carbonate, Zn5(OH)6(CO3)2, by reaction with atmospheric carbon dioxide.[25] This layer helps prevent

further reaction with air and water.

Zinc burns in air with a bright bluish-green flame, giving off fumes of zinc oxide.[26] Zinc reacts readily

with acids, alkalis and other non-metals.[27] Extremely pure zinc reacts only slowly at room temperature

with acids.[26] Strong acids, such as hydrochloric or sulfuric acid, can remove the passivating layer and

subsequent reaction with water releases hydrogen gas.[26]

The chemistry of zinc is dominated by the +2 oxidation state. When compounds in this oxidation state

are formed the outer shell s electrons are lost, which yields a bare zinc ion with the electronic

configuration [Ar]3d10.[28] In aqueous solution an octahedral complex, [Zn(H2O)6]2+ is the predominant

species.[29] The volatilization of zinc in combination with zinc chloride at temperatures above 285 °C

indicates the formation of Zn2Cl2, a zinc compound with a +1 oxidation state.[26] No compounds of zinc

in oxidation states other than +1 or +2 are known.[30]Calculations indicate that a zinc compound with

the oxidation state of +4 is unlikely to exist.[31]

Zinc chemistry is similar to the chemistry of the late first-row transition metals nickel and copper,

though it has a filled d-shell, so its compounds are diamagnetic and mostly colorless.[32] Theionic

radii of zinc and magnesium happen to be nearly identical. Because of this some of their salts have

the same crystal structure [33]  and in circumstances where ionic radius is a determining factor zinc and

magnesium chemistries have much in common.[26] Otherwise there is little similarity. Zinc tends to form

bonds with a greater degree of covalency and it forms much more stablecomplexes with N- and S-

donors.[32] Complexes of zinc are mostly 4- or 6- coordinate although 5-coordinate complexes are

known.[26]

See also Clemmensen reduction .

Zinc(I) compounds

Zinc(I) compounds are rare, and requires bulky ligands to stabilize the low oxidation state. Most zinc(I)

compounds contains formally the [Zn2]2+ core, which is analogous to the [Hg2]2+ dimeric cation present

in mercury(I) compounds. The diamagnetic nature of the ion confirms its dimeric structure. The first

zinc(I) compound containing the Zn—Zn bond, (η 5 -C 5Me5)2Zn2, is also the firstdimetallocene. The

[Zn2]2+ ion rapidly disproportionates into zinc metal and zinc(II), and has only been obtained as a

yellow glass formed by cooling a solution of metallic zinc in molten ZnCl2.[34]

Zinc (II) compounds

Zinc acetate

Zinc chloride

Binary compounds of zinc are known for most of the metalloids and all the nonmetals except the noble

gases. The oxide ZnOis a white powder that is nearly insoluble in neutral aqueous solutions, but

is amphoteric, dissolving in both strong basic and acidic solutions.[26] The

other chalcogenides (ZnS, ZnSe, and ZnTe) have varied applications in electronics and optics.

[35] Pnictogenides  (Zn3N2, Zn3P2, Zn3As2 and Zn3Sb2),[36][37] the peroxide (ZnO2), the hydride (ZnH2), and

the carbide (ZnC2) are also known.[38] Of the four halides, ZnF2 has the most ionic character, whereas

the others (ZnCl2, ZnBr2, and ZnI2) have relatively low melting points and are considered to have more

covalent character.[39]

In weak basic solutions containing Zn2+ ions, the hydroxide Zn(OH)2 forms as a white precipitate. In

stronger alkaline solutions, this hydroxide is dissolved to form zincates ([Zn(OH)4]2−).[26] The

nitrate Zn(NO3)2, chlorate Zn(ClO3)2, sulfateZnSO4, phosphate Zn3(PO4)2, molybdate ZnMoO4,

cyanide Zn(CN)2, arsenite Zn(AsO2)2, arsenate Zn(AsO4)2·8H2O and the chromate ZnCrO4 (one of the

few colored zinc compounds) are a few examples of other common inorganic compounds of zinc.[40]

[41] One of the simplest examples of an organic compound of zinc is the acetate (Zn(O2CCH3)2).

Organozinc compounds are those that contain zinc–carbon covalent bonds. Diethylzinc ((C2H5)2Zn) is

a reagent in synthetic chemistry. It was first reported in 1848 from the reaction of zinc andethyl iodide,

and was the first compound known to contain a metal–carbon sigma bond.[42]

History

Ancient use

Late Roman brass bucket – theHemmoorer Eimer from Warstade, Germany, second to third century AD

Various isolated examples of the use of impure zinc in ancient times have been discovered. A

possibly prehistoric statuette containing 87.5% zinc was found in a Dacian archaeological site

in Transylvania (modern Romania).[43] Ornaments made of alloys that contain 80–90% zinc with lead,

iron, antimony, and other metals making up the remainder, have been found that are 2500 years old.

[11] The Berne zinc tablet is a votive plaque dating to Roman Gaul made of an alloy that is mostly zinc.

[44] Also, some ancient writings appear to mention zinc. The Greek historian Strabo, in a passage

taken from an earlier writer of the 4th century BC, mentions "drops of false silver", which when mixed

with copper make brass. This may refer to small quantities of zinc by-product of smelting sulfideores.

[45] The Charaka Samhita , thought to have been written in 500 BC or before, mentions a metal which,

when oxidized, produces pushpanjan, thought to be zinc oxide.[46]

Zinc ores were used to make the zinc–copper alloy brass many centuries prior to the discovery of zinc

as a separate element. Judean brass from the 14th to 10th centuries BC contains 23% zinc.[47] The

Book of Genesis, written between the 10th and 5th centuries BC,[48] mentions (in the King James

translation)Tubal-cain as an "instructor of every artificer in brass and iron" (Genesis 4:22), but since

the word nechosheth, translated as "brass", also means "copper", the significance of this is not clear.

Knowledge of how to produce brass spread to Ancient Greece by the 7th century BC but few varieties

were made.[49]

The manufacture of brass was known to the Romans by about 30 BC.[50] They made brass by heating

powdered calamine (zinc silicate or carbonate), charcoal and copper together in a crucible.[50] The

resulting calamine brass was then either cast or hammered into shape and was used in weaponry.

[51] Some coins struck by Romans in the Christian era are made of what is probably calamine brass.

[52] In the West, impure zinc was known from antiquity to exist in the remnants in melting ovens, but it

was usually discarded, as it was thought to be worthless.[53]

Zinc mines at Zawar, near Udaipur in India, have been active since the Mauryan period  in the late 1st

millennium BC. The smelting of metallic zinc here however appears to have begun around the 12th

century AD.[54][55] One estimate is that this location produced an estimated million tonnes of metallic

zinc and zinc oxide from the 12th to 16th centuries.[13] Another estimate gives a total production of

60,000 tonnes of metallic zinc over this period.[54] The Rasaratna Samuccaya , written in approximately

the 13th century AD, mentions two types of zinc-containing ores; one used for metal extraction and

another used for medicinal purposes.[55]

Early studies and naming

Zinc was distinctly recognized as a metal under the designation of Yasada or Jasada in the medical

Lexicon ascribed to the Hindu king Madanapala and written about the year 1374.[56] Smelting and

extraction of impure zinc by reducing calamine with wool and other organic substances was

accomplished in the 13th century in India.[4][57] The Chinese did not learn of the technique until the 17th

century.[57]

Various alchemical symbols attributed to the element zinc

Alchemists burned zinc metal in air and collected the resulting zinc oxide on a condenser. Some

alchemists called this zinc oxide lana philosophica, Latin for "philosopher's wool", because it collected

in wooly tufts while others thought it looked like white snow and named it nix album.[58]

The name of the metal was probably first documented by Paracelsus, a Swiss-born German

alchemist, who referred to the metal as "zincum" or "zinken" in his book Liber Mineralium II, in the

16th century.[57][59] The word is probably derived from the German zinke, and supposedly meant "tooth-

like, pointed or jagged" (metallic zinc crystals have a needle-like appearance).[60] Zink could also imply

"tin-like" because of its relation to German zinnmeaning tin.[61] Yet another possibility is that the word

is derived from the Persian word سنگ seng meaning stone.[62] The metal was also called Indian tin,

tutanego, calamine, and spinter.[11]

German metallurgist Andreas Libavius received a quantity of what he called "calay" of Malabar from a

cargo ship captured from the Portuguese in 1596.[63] Libavius described the properties of the sample,

which may have been zinc. Zinc was regularly imported to Europe from the Orient in the 17th and

early 18th centuries,[57] but was at times very expensive.[note 1]

Isolation

Andreas Sigismund Marggrafis given credit for first isolating pure zinc

The isolation of metallic zinc in the West may have been achieved independently by several

people. Postlewayt's Universal Dictionary, a contemporary source giving technological information in

Europe, did not mention zinc before 1751 but the element was studied before then.[55][64]

Flemish metallurgist P.M. de Respour reported that he extracted metallic zinc from zinc oxide in 1668.

[13] By the start of the 18th century, Étienne François Geoffroy  described how zinc oxide condenses as

yellow crystals on bars of iron placed above zinc ore being smelted.[13] In Britain, John Lane is said to

have carried out experiments to smelt zinc, probably at Landore, prior to his bankruptcy in 1726.[65]

In 1738, William Champion patented in Great Britain a process to extract zinc from calamine in a

vertical retort style smelter.[66] His technology was somewhat similar to that used at Zawar zinc mines

in Rajasthan but there is no evidence that he visited the Orient.[67] Champion's process was used

through 1851.[57]

German chemist Andreas Marggraf normally gets credit for discovering pure metallic zinc even though

Swedish chemist Anton von Swab distilled zinc from calamine four years before.[57] In his 1746

experiment, Marggraf heated a mixture of calamine and charcoal in a closed vessel without copper to

obtain a metal.[53] This procedure became commercially practical by 1752.[68]

Later work

Galvanization was named afterLuigi Galvani.

William Champion's brother, John, patented a process in 1758 for calcining zinc sulfide into an oxide

usable in the retort process.[11] Prior to this only calamine could be used to produce zinc. In

1798, Johann Christian Ruberg improved on the smelting process by building the first horizontal retort

smelter.[69] Jean-Jacques Daniel Dony built a different kind of horizontal zinc smelter in Belgium, which

processed even more zinc.[57] Italian doctor Luigi Galvani discovered in 1780 that connecting

the spinal cord of a freshly dissected frog to an iron rail attached by a brass hook caused the frog's leg

to twitch.[70] He incorrectly thought he had discovered an ability of nerves and muscles to

create electricity and called the effect "animal electricity".[71] The galvanic cell and the process of

galvanization were both named for Luigi Galvani and these discoveries paved the way for electrical

batteries, galvanization and cathodic protection .[71]

Galvani's friend, Alessandro Volta, continued researching this effect and invented the Voltaic pile in

1800.[70] The basic unit of Volta's pile was a simplifiedgalvanic cell, which is made of a plate of copper

and a plate of zinc connected to each other externally and separated by an electrolyte. These were

stacked in series to make the Voltaic cell, which in turn produced electricity by directing electrons from

the zinc to the copper and allowing the zinc to corrode.[70]

The non-magnetic character of zinc and its lack of color in solution delayed discovery of its importance

to biochemistry and nutrition.[72] This changed in 1940 when carbonic anhydrase, an enzyme that

scrubs carbon dioxide from blood, was shown to have zinc in its active site.[72] The digestive

enzymecarboxypeptidase became the second known zinc-containing enzyme in 1955.[72]

Production

Mining and processing

Top zinc output countries 2010[14]

Rank Country Tonnes

1  China 3,500,000

2  Peru 1,520,000

3  Australia 1,450,000

4  India 750,000

5  United States 720,000

6  Canada 670,000

Main articles: Zinc mining and Zinc smelting

See also: List of countries by zinc production

Percentage of zinc output in 2006 by countries[73]

Zinc is the fourth most common metal in use, trailing only iron, aluminium, and copper with an annual

production of about 12 million tonnes.[14] The world's largest zinc producer is Nyrstar, a merger of the

Australian OZ Minerals and the Belgian Umicore.[74] About 70% of the world's zinc originates from

mining, while the remaining 30% comes from recycling secondary zinc.[75] Commercially pure zinc is

known as Special High Grade, often abbreviated SHG, and is 99.995% pure.[76]

Worldwide, 95% of the zinc is mined from sulfidic ore deposits, in which sphalerite ZnS is nearly

always mixed with the sulfides of copper, lead and iron.[77]There are zinc mines throughout the world,

with the main mining areas being China, Australia and Peru. China produced 29% of the global zinc

output in 2010.[14]

Zinc metal is produced using extractive metallurgy.[78] After grinding the ore, froth flotation, which

selectively separates minerals from gangue by taking advantage of differences in their hydrophobicity,

is used to get an ore concentrate.[78] A final concentration of zinc of about 50% is reached by this

process with the remainder of the concentrate being sulfur (32%), iron (13%), and SiO2(5%).[78]

Roasting converts the zinc sulfide concentrate produced during processing to zinc oxide:[77]

2 ZnS + 3 O2 → 2 ZnO + 2 SO2

The sulfur dioxide is used for the production of sulfuric acid, which is necessary for the leaching

process. If deposits of zinc carbonate, zinc silicate or zinc spinel, like the Skorpion Deposit  in

Namibia are used for zinc production the roasting can be omitted.[79]

For further processing two basic methods are used: pyrometallurgy or electrowinning.

Pyrometallurgy processing reduces zinc oxide with carbon or carbon monoxide at 950

°C (1,740 °F) into the metal, which is distilled as zinc vapor.[80] The zinc vapor is collected in a

condenser.[77] The below set of equations demonstrate this process:[77]

2 ZnO + C → 2 Zn + CO2

ZnO + CO → Zn + CO2

Electrowinning processing leaches zinc from the ore concentrate by sulfuric acid:[81]

ZnO + H2SO4 → ZnSO4 + H2O

After this step electrolysis is used to produce zinc metal.[77]

2 ZnSO4 + 2 H2O → 2 Zn + 2 H2SO4 + O2

The sulfuric acid regenerated is recycled to the leaching step.

Environmental impact

The production for sulfidic zinc ores produces large amounts of sulfur dioxide

and cadmium vapor. Smelter slag and other residues of process also contain

significant amounts of heavy metals. About 1.1 million tonnes of metallic zinc

and 130 thousand tonnes of lead were mined and smelted in the Belgian towns

of La Calamine and Plombières between 1806 and 1882.[82] The dumps of the

past mining operations leach significant amounts of zinc and cadmium, and, as

a result, the sediments of the Geul River  contain significant amounts of heavy

metals.[82] About two thousand years ago emissions of zinc from mining and

smelting totaled 10 thousand tonnes a year. After increasing 10-fold from 1850,

zinc emissions peaked at 3.4 million tonnes per year in the 1980s and declined

to 2.7 million tonnes in the 1990s, although a 2005 study of the Arctic

troposphere found that the concentrations there did not reflect the decline.

Anthropogenic and natural emissions occur at a ratio of 20 to 1.[83]

Levels of zinc in rivers flowing through industrial or mining areas can be as

high as 20 ppm.[84] Effective sewage treatment greatly reduces this; treatment

along the Rhine, for example, has decreased zinc levels to 50 ppb.

[84] Concentrations of zinc as low as 2 ppm adversely affects the amount of

oxygen that fish can carry in their blood.[85]

Historically responsible for high heavy metal levels in the Derwent River ,[86] the zinc

works at Lutana is the largest exporter in Tasmania, generating 2.5% of the state's GDP,

and producing over 250 thousand tonnes of zinc per year.[87]

Soils contaminated with zinc through the mining of zinc-containing ores,

refining, or where zinc-containing sludge is used as fertilizer, can contain

several grams of zinc per kilogram of dry soil. Levels of zinc in excess of

500 ppm in soil interfere with the ability of plants to absorb other essential

metals, such as iron and manganese. Zinc levels of 2000 ppm to 180,000 ppm

(18%) have been recorded in some soil samples.[84]

Applications

Major applications of zinc include (numbers are given for the US)[88]

1. Galvanizing  (55%)

2. Alloys (21%)

3. Brass  and bronze (16%)

4. Miscellaneous (8%)

Anti-corrosion and batteries

Hot-dip handrail galvanized crystalline surface

The metal is most commonly used as an anti-corrosion agent.[89] Galvanization,

which is the coating of iron or steel to protect the metals againstcorrosion, is

the most familiar form of using zinc in this way. In 2009 in the United States,

55% or 893 thousand tonnes of the zinc metal was used for galvanization.[88]

Zinc is more reactive than iron or steel and thus will attract almost all local

oxidation until it completely corrodes away.[90] A protective surface layer of

oxide and carbonate (Zn5(OH)6(CO3)2) forms as the zinc corrodes.[91] This

protection lasts even after the zinc layer is scratched but degrades through

time as the zinc corrodes away.[91] The zinc is applied electrochemically or as

molten zinc by hot-dip galvanizing or spraying. Galvanization is used on chain-

link fencing, guard rails, suspension bridges, lightposts, metal roofs, heat

exchangers, and car bodies.[10]

The relative reactivity of zinc and its ability to attract oxidation to itself makes it

an efficient sacrificial anode in cathodic protection  (CP). For example, cathodic

protection of a buried pipeline can be achieved by connecting anodes made

from zinc to the pipe.[91] Zinc acts as the anode (negative terminus) by slowly

corroding away as it passes electric current to the steel pipeline.[91][note 2] Zinc is

also used to cathodically protect metals that are exposed to sea water from

corrosion.[92] A zinc disc attached to a ship's iron rudder will slowly corrode

while the rudder stays unattacked.[90] Other similar uses include a plug of zinc

attached to a propeller or the metal protective guard for the keel of the ship.

With a standard electrode potential (SEP) of −0.76 volts, zinc is used as an

anode material for batteries. (More reactive lithium (SEP −3.04 V) is used for

anodes in lithium batteries ). Powdered zinc is used in this way in alkaline

batteries and sheets of zinc metal form the cases for and act as anodes

in zinc–carbon batteries.[93][94] Zinc is used as the anode or fuel of the zinc-air

battery/fuel cell.[95][96][97]

Alloys

A widely used alloy which contains zinc is brass, in which copper is alloyed

with anywhere from 3% to 45% zinc, depending upon the type of brass.

[91] Brass is generally more ductile and stronger than copper and has

superior corrosion resistance.[91] These properties make it useful in

communication equipment, hardware, musical instruments, and water valves.[91]

Cast brass microstructure at magnification 400x

Other widely used alloys that contain zinc include nickel silver, typewriter

metal, soft and aluminium solder, and commercial bronze.[4] Zinc is also used in

contemporary pipe organs as a substitute for the traditional lead/tin alloy in

pipes.[98] Alloys of 85–88% zinc, 4–10% copper, and 2–8% aluminium find

limited use in certain types of machine bearings. Zinc is the primary metal used

in making American one cent coins since 1982.[99] The zinc core is coated with

a thin layer of copper to give the impression of a copper coin. In 1994, 33,200

tonnes (36,600 short tons) of zinc were used to produce 13.6 billion pennies in

the United States.[100]

Alloys of primarily zinc with small amounts of copper, aluminium, and

magnesium are useful in die casting as well as spin casting, especially in the

automotive, electrical, and hardware industries.[4] These alloys are marketed

under the name Zamak.[101] An example of this is zinc aluminium. The low

melting point together with the low viscosity of the alloy makes the production

of small and intricate shapes possible. The low working temperature leads to

rapid cooling of the cast products and therefore fast assembly is possible.[4]

[102] Another alloy, marketed under the brand name Prestal, contains 78% zinc

and 22% aluminium and is reported to be nearly as strong as steel but as

malleable as plastic.[4][103] This superplasticity of the alloy allows it to be molded

using die casts made of ceramics and cement.[4]

Similar alloys with the addition of a small amount of lead can be cold-rolled into

sheets. An alloy of 96% zinc and 4% aluminium is used to make stamping dies

for low production run applications for which ferrous metal dies would be too

expensive.[104] In building facades, roofs or other applications in which zinc is

used as sheet metal and for methods such as deep drawing, roll

forming or bending, zinc alloys with titanium and copper are used.[105] Unalloyed

zinc is too brittle for these kinds of manufacturing processes.[105]

As a dense, inexpensive, easily worked material, zinc is used as

a lead replacement. In the wake of lead concerns, zinc appears in weights for

various applications ranging from fishing[106] to tire balances and flywheels.[107]

Cadmium zinc telluride (CZT) is a semiconductive alloy that can be divided into

an array of small sensing devices.[108] These devices are similar to

an integrated circuit and can detect the energy of incoming gamma

ray photons.[108] When placed behind an absorbing mask, the CZT sensor array

can also be used to determine the direction of the rays.[108]

Other industrial uses

Zinc oxide is used as a white pigment inpaints.

Roughly one quarter of all zinc output in the United States (2009), is consumed

in the form of zinc compounds;[88] a variety of which are used industrially. Zinc

oxide is widely used as a white pigment in paints, and as a catalyst in the

manufacture of rubber. It is also used as a heat disperser for the rubber and

acts to protect its polymers from ultraviolet radiation (the same UV protection is

conferred to plastics containing zinc oxide).[10] Thesemiconductor properties of

zinc oxide make it useful in varistors and photocopying products.[109] The zinc

zinc-oxide cycle is a two stepthermochemical process based on zinc and zinc

oxide for hydrogen production.[110]

Zinc chloride is often added to lumber as a fire retardant [111]  and can be used as

a wood preservative.[112] It is also used to make other chemicals.[111] Zinc

methyl (Zn(CH3)2) is used in a number of organic syntheses.[113] Zinc

sulfide (ZnS) is used in luminescent pigments such as on the hands of

clocks, X-ray and television screens, and luminous paints.[114] Crystals of ZnS

are used in lasers that operate in the mid-infrared part of the spectrum.[115] Zinc

sulfate is a chemical in dyes and pigments.[111] Zinc pyrithione is used

in antifouling paints.[116]

Zinc powder is sometimes used as a propellant in model rockets.[117] When a

compressed mixture of 70% zinc and 30% sulfur powder is ignited there is a

violent chemical reaction.[117] This produces zinc sulfide, together with large

amounts of hot gas, heat, and light.[117] Zinc sheet metal is used to make

zinc bars.[118]

64Zn, the most abundant isotope of zinc, is very susceptible to neutron

activation, being transmuted into the highly radioactive 65Zn, which has a half-

life of 244 days and produces intense gamma radiation. Because of this, Zinc

Oxide used in nuclear reactors as an anti-corrosion agent is depleted

of 64Zn before use, this is called depleted zinc oxide. For the same reason, zinc

has been proposed as a salting material for nuclear weapons (cobalt is

another, better-known salting material).[119] A jacket of isotopically

enriched 64Zn would be irradiated by the intense high-energy neutron flux from

an exploding thermonuclear weapon, forming a large amount

of 65Zn significantly increasing the radioactivity of the weapon's fallout.[119]Such

a weapon is not known to have ever been built, tested, or used.[119] 65Zn is also

used as a tracer to study how alloys that contain zinc wear out, or the path and

the role of zinc in organisms.[120]

Zinc dithiocarbamate complexes are used as agricultural fungicides; these

include Zineb, Metiram, Propineb and Ziram.[121] Zinc naphthenate is used as

wood preservative.[122] Zinc, in the form ofZDDP, is also used as an anti-wear

additive for metal parts in engine oil.[123]

Dietary supplement

GNC zinc 50 mg tablets (AU)

Zinc is included in most single tablet over-the-counter daily vitamin

and mineral supplements.[124] Preparations include zinc oxide, zinc acetate,

and zinc gluconate.[124] It is believed to possess antioxidant properties, which

may protect against accelerated aging of the skin and muscles of the body;

studies differ as to its effectiveness.[125] Zinc also helps speed up the healing

process after an injury.[125] It is also beneficial to the body's immune system.

Indeed, zinc deficiency may have effects on virtually all parts of the human

immune system.[126] The efficacy of zinc compounds when used to reduce the

duration or severity of cold symptoms is controversial.[127] A 2011 systematic

review concludes that supplementation yields a mild decrease in duration and

severity of cold symptoms.[128]

Zinc serves as a simple, inexpensive, and critical tool for treating diarrheal

episodes among children in the developing world. Zinc becomes depleted in

the body during diarrhea, but recent studies suggest that replenishing zinc with

a 10- to 14-day course of treatment can reduce the duration and severity of

diarrheal episodes and may also prevent future episodes for up to three

months.[129]

Zinc gluconate is one compound used for the delivery of zinc as a dietary supplement.

The Age-Related Eye Disease Study determined that zinc can be part of an

effective treatment for age-related macular degeneration.[130] Zinc

supplementation is an effective treatment for acrodermatitis enteropathica , a

genetic disorder affecting zinc absorption that was previously fatal to babies

born with it.[50]

Gastroenteritis is strongly attenuated by ingestion of zinc, and this effect could

be due to direct antimicrobial action of the zinc ions in the gastrointestinal tract,

or to the absorption of the zinc and re-release from immune cells

(allgranulocytes secrete zinc), or both.[131][132][note 3] In 2011, researchers at John

Jay College of Criminal Justicereported that dietary zinc supplements can

mask the presence of drugs in urine. Similar claims have been made in web

forums on that topic.[133]

Although not yet tested as a therapy in humans, a growing body of evidence

indicates that zinc may preferentially kill prostate cancer cells. Because zinc

naturally homes to the prostate and because the prostate is accessible with

relatively non-invasive procedures, its potential as a chemotherapeutic agent in

this type of cancer has shown promise.[134] However, other studies have

demonstrated that chronic use of zinc supplements in excess of the

recommended dosage may actually increase the chance of developing

prostate cancer, also likely due to the natural buildup of this heavy metal in the

prostate.[135]

Topical use

Further information: Zinc oxide#Medical

Topical administration of zinc preparations include ones used on the skin, often

in the form of zinc oxide. Zinc preparations can protect against sunburn in the

summer and windburn in the winter.[50] Applied thinly to a baby's diaper area

(perineum) with each diaper change, it can protect against diaper rash.[50]

Zinc lactate is used in toothpaste to prevent halitosis.[136] Zinc pyrithione is

widely applied in shampoos because of its anti-dandruff function.[137] Zinc ions

are effective antimicrobial agents even at low concentrations.[138]

Organic chemistry

Addition of diphenylzinc to an aldehyde

There are many important organozinc compounds . Organozinc chemistry is the

science of organozinc compounds describing their physical properties,

synthesis and reactions.[139][140][141][142] Among important applications is the

Frankland-Duppa Reaction in which an oxalate ester(ROCOCOOR) reacts with

an alkyl halide R'X, zinc and hydrochloric acid to the α-hydroxycarboxylic

esters RR'COHCOOR,[143] the Reformatskii reaction  which converts α-halo-

esters and aldehydes to β-hydroxy-esters, the Simmons–Smith reaction in

which the carbenoid (iodomethyl)zinc iodide reacts with alkene(or alkyne) and

converts them to cyclopropane, the Addition reaction of organozinc compounds

to carbonyl compounds. The Barbier reaction (1899) which is the zinc

equivalent of the magnesium Grignard reaction and is better of the two. In

presence of just about any water the formation of the organomagnesium halide

will fail whereas the Barbier reaction can even take place in water. On the

downside organozincs are much less nucleophilic than Grignards, are

expensive and difficult to handle. Commercially available diorganozinc

compounds are dimethylzinc, diethylzinc and diphenylzinc. In one study[144]

[145] the active organozinc compound is obtained from much

cheaper organobromine precursors:

The Negishi coupling  is also an important reaction for the formation of new

carbon carbon bonds between unsaturated carbon atoms in alkenes, arenes

and alkynes. The catalysts are nickel and palladium. A key step in the catalytic

cycle is atransmetalation in which a zinc halide exchanges its organic

substituent for another halogen with the palladium (nickel) metal center.

The Fukuyama coupling is another coupling reaction but this one with a

thioester as reactant forming a ketone.

Biological role

Zinc is an essential trace element, necessary for plants,[83] animals,

[146] and microorganisms.[147] Zinc is found in nearly 100

specific enzymes [148]  (other sources say 300), serves as structural ions

in transcription factors and is stored and transferred in metallothioneins.[149] It is

"typically the second most abundant transition metal in organisms" after iron

and it is the only metal which appears in all enzyme classes.[83]

In proteins, Zn ions are often coordinated to the amino acid side chains of

aspartic acid, glutamic acid, cysteine and histidine. The theoretical and

computational description of this zinc binding in proteins (as well as that of

other transition metals) is difficult.[150]

There are 2-4 grams of zinc[151] distributed throughout the human body. Most

zinc is in the brain, muscle, bones, kidney, and liver, with the highest

concentrations in the prostate and parts of the eye.[152] Semen is particularly

rich in zinc, which is a key factor in prostate gland function and reproductive

organ growth.[153]

In humans, zinc plays "ubiquitous biological roles".[1] It interacts with "a wide

range of organic ligands",[1] and has roles in the metabolism of RNA and

DNA, signal transduction, and gene expression. It also regulates apoptosis. A

2006 study estimated that about 10% of human proteins (2800) potentially bind

zinc, in addition to hundreds which transport and traffic zinc; a similar in

silico study in the plant Arabidopsis thaliana found 2367 zinc-related proteins.

[83]

In the brain, zinc is stored in specific synaptic

vesicles by glutamatergic neurons[154] and can "modulate brain excitability".[1] It

plays a key role in synaptic plasticity and so in learning.[155]However it has been

called "the brain's dark horse"[154] since it also can be a neurotoxin, suggesting

zinc homeostasis plays a critical role in normal functioning of the brain

and central nervous system.[154]

Enzymes

Ribbon diagram of human carbonic anhydrase II, with zinc atom visible in the center

Zinc fingers help read DNA sequences.

Zinc is an efficient Lewis acid, making it a useful catalytic agent

in hydroxylation and other enzymatic reactions.[148] The metal also has a

flexible coordination geometry, which allows proteins using it to rapidly

shift conformations to perform biological reactions.[156] Two examples of zinc-

containing enzymes arecarbonic anhydrase and carboxypeptidase, which are

vital to the processes of carbon dioxide (CO2) regulation and digestion of

proteins, respectively.[157]

In vertebrate blood, carbonic anhydrase converts CO2 into bicarbonate and the

same enzyme transforms the bicarbonate back into CO2 for exhalation through

the lungs.[158] Without this enzyme, this conversion would occur about one

million times slower[159] at the normal blood pH of 7 or would require a pH of 10

or more.[160] The non-related β-carbonic anhydrase is required in plants for leaf

formation, the synthesis of indole acetic acid (auxin) and alcoholic

fermentation.[161]

Carboxypeptidase cleaves peptide linkages during digestion of proteins.

A coordinate covalent bond is formed between the terminal peptide and a C=O

group attached to zinc, which gives the carbon a positive charge. This helps to

create a hydrophobicpocket on the enzyme near the zinc, which attracts the

non-polar part of the protein being digested.[157]

Other proteins

Zinc serves a purely structural role in zinc fingers, twists and clusters.[162] Zinc

fingers form parts of some transcription factors, which are proteins that

recognize DNA base sequences during the replication and transcription

of DNA. Each of the nine or ten Zn2+ ions in a zinc finger helps maintain the

finger's structure by coordinately binding to four amino acids in the transcription

factor.[159]The transcription factor wraps around the DNA helix and uses its

fingers to accurately bind to the DNA sequence.

In blood plasma, zinc is bound to and transported by albumin (60%, low-

affinity) and transferrin (10%).[151] Since transferrin also transports iron,

excessive iron reduces zinc absorption, and vice-versa. A similar reaction

occurs with copper.[163] The concentration of zinc in blood plasma stays

relatively constant regardless of zinc intake.[164] Cells in the salivary gland,

prostate, immune system and intestine use zinc signaling as one way to

communicate with other cells.[165]

Zinc may be held in metallothionein reserves within microorganisms or in the

intestines or liver of animals.[166] Metallothionein in intestinal cells is capable of

adjusting absorption of zinc by 15–40%.[167] However, inadequate or excessive

zinc intake can be harmful; excess zinc particularly impairs copper absorption

because metallothionein absorbs both metals.[168]

Reference ranges for blood tests, showing zinc in purple at center-right

Dietary intake

Foods & spices containing zinc

In the U.S., the Recommended Dietary Allowance (RDA) is 8 mg/day for

women and 11 mg/day for men.[169] Median intake in the U.S. around 2000 was

9 mg/day for women and 14 mg/day in men.[170] Oysters, lobster[171] and red

meats, especially beef, lamb and liver have some of the highest concentrations

of zinc in food.[153]

The concentration of zinc in plants varies based on levels of the element in soil.

When there is adequate zinc in the soil, the food plants that contain the most

zinc are wheat (germ and bran) and various seeds

(sesame, poppy, alfalfa, celery, mustard).[172] Zinc is also found

in beans, nuts, almonds, whole grains,pumpkin seeds, sunflower

seeds and blackcurrant.[173]

Other sources include fortified food and dietary supplements, which come in

various forms. A 1998 review concluded that zinc oxide, one of the most

common supplements in the United States, and zinc carbonate are nearly

insoluble and poorly absorbed in the body.[174] This review cited studies which

found low plasma zinc concentrations after zinc oxide and zinc carbonate were

consumed compared with those seen after consumption of zinc acetate and

sulfate salts.[174] However, harmful excessive supplementation is a problem

among the relatively affluent, and should probably not exceed 20 mg/day in

healthy people,[175] although the U.S. National Research Council set a Tolerable

Upper Intake of 40 mg/day.[176]

For fortification, however, a 2003 review recommended zinc oxide in cereals as

cheap, stable, and as easily absorbed as more expensive forms.[177] A 2005

study found that various compounds of zinc, including oxide and sulfate, did

not show statistically significant differences in absorption when added as

fortificants to maize tortillas.[178] A 1987 study found that zinc picolinate was

better absorbed than zinc gluconate or zinc citrate.[179] However, a study

published in 2008 determined that zinc glycinate is the best absorbed of the

four dietary supplement types available.[180]

Deficiency

Main article: Zinc deficiency

Zinc deficiency is usually due to insufficient dietary intake, but can be

associated with malabsorption, acrodermatitis enteropathica , chronic liver

disease, chronic renal disease, sickle cell disease, diabetes, malignancy, and

other chronic illnesses.[2] Symptoms of mild zinc deficiency are diverse.

[170] Clinical outcomes include depressed growth, diarrhea, impotence and

delayed sexual maturation, alopecia, eye and skin lesions, impaired appetite,

altered cognition, impaired host defense properties, defects in carbohydrate

utilization, and reproductive teratogenesis.[164]Mild zinc deficiency depresses

immunity,[181] although excessive zinc does also.[151] Animals with a diet

deficient in zinc require twice as much food in order to attain the same weight

gain as animals given sufficient zinc.[114]

Groups at risk for zinc deficiency include the elderly, children in developing

countries, and those with renal insufficiency. The zinc chelator phytate, found

in seeds and cereal bran, can contribute to zinc malabsorption.[2]

Despite some concerns,[182] western vegetarians and vegans have not been

found to suffer from overt zinc deficiencies any more than meat-eaters.

[183] Major plant sources of zinc include cooked dried beans, sea vegetables,

fortified cereals, soyfoods, nuts, peas, and seeds.[182] However, phytates in

many whole-grains and fiber in many foods may interfere with zinc absorption

and marginal zinc intake has poorly understood effects. There is some

evidence to suggest that more than the US RDA (15 mg) of zinc daily may be

needed in those whose diet is high in phytates, such as some vegetarians.

[182] These considerations must be balanced against the fact that there is a

paucity of adequate zinc biomarkers, and the most widely used indicator,

plasma zinc, has poor sensitivity and specificity.[184] Diagnosing zinc deficiency

is a persistent challenge.[1]

Nearly two billion people in the developing world are deficient in zinc.[2] In

children it causes an increase in infection and diarrhea, contributing to the

death of about 800,000 children worldwide per year.[1] The World Health

Organization advocates zinc supplementation for severe malnutrition and

diarrhea.[185] Zinc supplements help prevent disease and reduce mortality,

especially among children with low birth weight or stunted growth.[185] However,

zinc supplements should not be administered alone, since many in the

developing world have several deficiencies, and zinc interacts with other

micronutrients.[186]

Dreaming

Some supplemental zinc users report an increase in vivid dreaming.

Argriculture

Zinc deficiency is crop plants' most common micronutrient deficiency; it is

particularly common in high-pH soils.[187] Zinc-deficient soil is cultivated in the

cropland of about half of Turkey and India, a third of China, and most of

Western Australia, and substantial responses to zinc fertilization have been

reported in these areas.[83] Plants that grow in soils that are zinc-deficient are

more susceptible to disease. Zinc is primarily added to the soil through the

weathering of rocks, but humans have added zinc through fossil fuel

combustion, mine waste, phosphate fertilizers, limestone, manure, sewage

sludge, and particles from galvanized surfaces. Excess zinc is toxic to plants,

although zinc toxicity is far less widespread.[83]

Precautions

Main article: Zinc toxicity

Toxicity

Although zinc is an essential requirement for good health, excess zinc can be

harmful. Excessive absorption of zinc suppresses copper and iron absorption.

[168] The free zinc ion in solution is highly toxic to plants, invertebrates, and even

vertebrate fish.[188] The Free Ion Activity Model is well-established in the

literature, and shows that just micromolar amounts of the free ion kills some

organisms. A recent example showed 6 micromolar killing 93% of

all Daphnia in water.[189]

The free zinc ion is a powerful Lewis acid up to the point of being corrosive.

Stomach acid contains hydrochloric acid, in which metallic zinc dissolves

readily to give corrosive zinc chloride. Swallowing a post-1982 American

one cent piece (97.5% zinc) can cause damage to the stomach lining due to

the high solubility of the zinc ion in the acidic stomach.[190]

There is evidence of induced copper deficiency at low intakes of 100–300 mg

Zn/day; a recent trial had higher hospitalizations for urinary complications

compared to placebo among elderly men taking 80 mg/day.

[191] The USDA RDA is 11 and 8 mg Zn/day for men and women, respectively.

[169] Even lower levels, closer to the RDA, may interfere with the utilization of

copper and iron or adversely affect cholesterol.[168] Levels of zinc in excess of

500 ppm in soil interfere with the ability of plants to absorb other essential

metals, such as iron and manganese.[84] There is also a condition called

the zinc shakes or "zinc chills" that can be induced by the inhalation of freshly

formed zinc oxide formed during the welding of galvanized materials.[114] Zinc is

a common ingredient of denture cream which may contain between 17 and

38 mg of zinc per gram. There have been cases of disability or even death due

to excessive use of these products.[192]

The U.S. Food and Drug Administration (FDA) has stated that zinc damages

nerve receptors in the nose, which can cause anosmia. Reports of anosmia

were also observed in the 1930s when zinc preparations were used in a failed

attempt to prevent polio infections.[193] On June 16, 2009, the FDA said that

consumers should stop using zinc-based intranasal cold products and ordered

their removal from store shelves. The FDA said the loss of smell can be life-

threatening because people with impaired smell cannot detect leaking gas or

smoke and cannot tell if food has spoiled before they eat it.[194] Recent research

suggests that the topical antimicrobial zinc pyrithione is a potent heat

shock response inducer that may impair genomic integrity with induction

of PARP-dependent energy crisis in cultured

human keratinocytes and melanocytes.[195]

Poisoning

In 1982, the United States Mint began minting pennies coated in copper but

made primarily of zinc. With the new zinc pennies, there is the potential for zinc

toxicosis, which can be fatal. One reported case of chronic ingestion of 425

pennies (over 1 kg of zinc) resulted in death due to gastrointestinal bacterial

and fungal sepsis, while another patient, who ingested 12 grams of zinc, only

showed lethargy and ataxia (gross lack of coordination of muscle movements).

[196] Several other cases have been reported of humans suffering zinc

intoxication by the ingestion of zinc coins.[197][198]

Pennies and other small coins are sometimes ingested by dogs, resulting in the

need for medical treatment to remove the foreign body. The zinc content of

some coins can cause zinc toxicity, which is commonly fatal in dogs, where it

causes a severe hemolytic anemia, and also liver or kidney damage; vomiting

and diarrhea are possible symptoms.[199] Zinc is highly toxic in parrots and

poisoning can often be fatal.[200] The consumption of fruit juices stored in

galvanized cans has resulted in mass parrot poisonings with zinc.[50]

inc is a metal. It is called an “essential trace element” because very small amounts of zinc are necessary for human health.

Zinc is used for treatment and prevention of zinc deficiency and its consequences, including stunted growth and acute diarrhea in children, and slow wound healing.

It is also used for boosting the immune system, treating the common cold and recurrent ear infections, and preventing lower respiratory infections. It is also used for malaria and other diseases caused by parasites.

Some people use zinc for an eye disease called macular degeneration, for night blindness, and for cataracts. It is also used for asthma; diabetes; high blood pressure; acquired immunodeficiency syndrome (AIDS); and skin conditions such aspsoriasis, eczema, and acne.

Other uses include treating attention deficit-hyperactivity disorder (ADHD), blunted sense of taste (hypogeusia), ringing in the ears (tinnitus), severe head injuries, Crohn’s disease, Alzheimer’s disease, Down syndrome, Hansen’s disease, ulcerative colitis, peptic ulcers and promoting weight gain in people with eating disorders such as anorexia nervosa.

Some people use zinc for benign prostatic hyperplasia (BPH), male infertility, erectile dysfunction (ED), weak bones (osteoporosis), rheumatoid arthritis, and muscle cramps associated with liver disease. It is also used for sickle cell disease and inherited disorders such as acrodermatitis enteropathica, thalassemia, and Wilson’s disease.

Some athletes use zinc for improving athletic performance and strength.

Zinc is also applied to the skin for treating acne, aging skin, herpes simplexinfections, and to speed wound healing.

There is a zinc preparation that can be sprayed in the nostrils for treating the common cold.

Zinc sulfate is used in products for eye irritation.

Zinc citrate is used in toothpaste and mouthwash to prevent dental plaque formation and gingivitis.

Note that many zinc products also contain another metal called cadmium. This is because zinc and cadmium are chemically similar and often occur together in nature. Exposure to high levels of cadmium over a long time can lead to kidney failure. The concentration of cadmium in zinc-containing supplements can vary as much as 37-fold. Look for zinc-gluconate products. Zinc gluconate consistently contains the lowest cadmium levels.

How does it work?Zinc is needed for the proper growth and maintenance of the human body. It is found in several systems and biological reactions, and it is needed for immune function, wound healing, blood clotting, thyroid function, and much more. Meats, seafood, dairy products, nuts, legumes, and whole grains offer relatively high levels of zinc.

Zinc deficiency is not uncommon worldwide, but is rare in the US. Symptoms include slowed growth, low insulin levels, loss of appetite, irritability, generalized hair loss, rough and dry skin, slow wound healing, poor sense of taste

and smell, diarrhea, and nausea. Moderate zinc deficiency is associated with disorders of the intestine which interfere with food absorption (malabsorption syndromes), alcoholism, chronic kidney failure, and chronic debilitating diseases.

Zinc plays a key role in maintaining vision, and it is present in high concentrations in the eye. Zinc deficiency can alter vision, and severe deficiency can cause changes in the retina (the back of the eye where an image is focused).

Zinc might also have effects against viruses. It appears to lessen symptoms of the rhinovirus (common cold), but researchers can’t yet explain exactly how this works. In addition, there is some evidence that zinc has some antiviral activity against the herpes virus.

Low zinc levels can be associated with male infertility, sickle cell disease, HIV, major depression, and type 2 diabetes, and can be fought by taking a zinc supplement.

Preventing and treating blood levels of zinc that are too low (zinc deficiency). Zinc deficiency may occur in severe diarrhea, conditions that make it hard for the bowel to absorb food, liver cirrhosis and alcoholism, after major surgery, and during long-term use of tube feeding in the hospital. Taking zinc by mouth or intravenously (by IV) helps to restore zinc levels to the right level. But as a rule, routine use of zinc supplements is not recommended.

Likely Effective for:

Reducing diarrhea in malnourished children, or in children who have low zinc levels. Severe zinc deficiency in children is common in developing countries.

Treating Wilson’s disease, a rare genetic disorder.

Possibly Effective for:

Decreasing the length of time the common cold lasts, when taken by mouth as a lozenge. However, using zinc as a pill or a nose spray doesn’t seem to help prevent colds.

Acne. Taking zinc by mouth or applying it to the skin in an ointment that also contains erythromycin seems to help clear up acne.

Weak bones (osteoporosis). Low zinc intake seems to be linked to lower bone mass. Taking a zinc supplement in combination with copper, manganese, and calcium might also decrease bone loss in women who have passed menopause.

Treating an eye disease called age-related macular degeneration (AMD) when taken with other medicines. Taking zinc by mouth in combination with antioxidant vitamins (vitamin C, vitamin E, and beta-carotene) might slow the worsening of advanced age-related macular degeneration (AMD). There isn’t enough information to know if zinc plus antioxidants helps people with less advanced macular disease or prevents AMD. Taking zinc supplements alone does not seem to benefit people with existing AMD.

Treating attention deficit-hyperactivity disorder (ADHD). Taking zinc by mouth in combination with conventional treatment might slightly improve symptoms of hyperactivity, impulsiveness, and socialization problems in some children with ADHD. But zinc might not improve attention span. Some research suggests that children with ADHD have lower zinc levels in their blood than children without ADHD. Other research suggests people with ADHD with lower zinc levels might not respond well enough to prescription medications for ADHD (stimulants). Studies using zinc for ADHD have taken place in the Middle East where zinc deficiency is relatively common compared to Western countries. It’s not known if zinc would have the same potential benefits when used for ADHD in people from Western countries.

Treating an inherited disorder called acrodermatitis enteropathica.

Leprosy, when used with other medications.

Herpes simplex virus  when zinc preparations made for the skin are applied directly to the mouth or genitals.

Promoting weight gain and improving depression in people with eating disorders such as anorexia nervosa.

Treating hypogeusia, a rare condition where the sense of taste is abnormal.

Preventing and treating stomach ulcers.

Preventing complications related to sickle cell anemia in people who have low zinc levels.

Preventing muscle cramps in people who have low zinc levels.

Treating leg wounds in people with low zinc levels.

As a mouthwash or toothpaste for preventing tartar and gingivitis.

Improving healing of burns.

Increasing vitamin A levels in underfed children or in children with low zinc levels.

Preventing and treating pneumonia in undernourished children in developing countries.

Possibly Ineffective for:

Preventing prostate cancer. Some preliminary research suggests that some men might benefit from taking zinc along with other vitamins and minerals for preventing prostate cancer. But other research suggests that taking zinc can increase the risk of developing prostate cancer and increase the risk of dying from prostate cancer.

Raising blood iron levels in pregnant women, when taken with iron and folic acid supplements.

Skin conditions including eczema, psoriasis, or hair loss.

Many kinds of arthritis.

Preventing or treating cataracts.

Malaria in underfed children.

Inflammatory bowel disease.

“Ringing in the ears” (tinnitus).

AIDS diarrhea-wasting syndrome.

Preventing the flu.

Increasing birth weight and gestation time in infants born to HIV-infected women.

Insufficient Evidence for:

Alzheimer’s disease. Some limited research has shown zinc supplements may slightly slow the worsening of symptoms in people with Alzheimer’s disease.

Wrinkled skin. A skin cream containing 10% vitamin C as L-ascorbic acid and acetyl tyrosine, zinc sulfate, sodium hyaluronate, and bioflavonoids (Cellex-C High Potency Serum) applied for 3 months to facial skin aged by sun exposure seems to improve fine and coarse wrinkling, yellowing, roughness, and skin tone.

Infections related to AIDS. There is some limited evidence that taking zinc supplements by mouth in combination with zidovudine (AZT, Retrovir, a component of Combivir) might prevent certain bacterial and yeast infections that can occur in people with AIDS because their immune system is less active than it should be. However, taking zinc supplements might lower the overall survival of people with AIDS.

Male sexual problems. Taking zinc orally to treat male sexual problems caused by disease or medical treatment has produced varying results.

Crohn’s disease.

Ulcerative colitis.

Diabetes.

Treating the common cold when used as a nose spray.

Asthma.

Down syndrome.

Recurrent ear infections.

Preventing cancer.

Head injury.

Helping babies that are too small when born.

Preventing esophageal cancer.

Other conditions.

More evidence is needed to rate zinc for these uses.

Zinc is LIKELY SAFE for most adults when applied to the skin, or when taken by mouth in amounts not larger than 40 mg per day. Routine zinc supplementation is not recommended without the advice of a healthcare professional. In some people, zinc might cause nausea, vomiting, diarrhea, metallic taste, kidney and stomach damage, and other side effects. Using zinc on broken skin may cause burning, stinging, itching, and tingling.

Taking high amounts of zinc is LIKELY UNSAFE. High doses above the recommended amounts might cause fever, coughing, stomach pain, fatigue, and many other problems.

Taking more than 100 mg of supplemental zinc daily or taking supplemental zinc for 10 or more years doubles the risk of developing prostate cancer. There is also concern that taking large amounts of a multivitamin plus a separate zinc supplement increases the chance of dying from prostate cancer.

Taking 450 mg or more of zinc daily can cause problems with blood iron. Single doses of 10-30 grams of zinc can be fatal.

Zinc nose sprays (Zicam, Cold-Eeze) are POSSIBLY UNSAFE. These products may cause loss of ability to smell. In June 2009, the US Food and Drug Administration (FDA) advised consumers not to use certain zinc-containing nose sprays (Zicam) after receiving over 100 reports of loss of smell. The maker of these zinc-containing nose sprays has also received several hundred reports of loss of smell from people who had used the products. Avoid using zinc nose sprays.Special Precautions & Warnings:Pregnancy and breast-feeding: Zinc is LIKELY SAFE for most pregnant and breast-feeding women when used in the recommended daily amounts (RDA). Pregnant women over 18 should not take more than 40 mg of zinc per day; pregnant women age 14 to 18 should not take more than 34 mg per day. Breast-feeding women over 18 should not take more than 40 mg of zinc per day; breast-feeding women age 14 to 18 should not take more than 34 mg per day.

HIV (human immunodeficiency virus)/AIDS: Do not take zinc if you have HIV/AIDS. Zinc might shorten your life.

interactions

Antibiotics (Quinolone antibiotics) interacts with ZINC

Zinc might decrease how much antibiotic the body absorbs. Taking zinc along with some antibiotics might decrease the effectiveness of some antibiotics. To avoid this interaction take zinc supplements at least 1 hour after antibiotics.Some of these antibiotics that might interact with zinc include ciprofloxacin (Cipro), enoxacin (Penetrex), norfloxacin (Chibroxin, Noroxin), sparfloxacin (Zagam), trovafloxacin (Trovan), and grepafloxacin (Raxar).

Antibiotics (Tetracycline antibiotics) interacts with ZINC

Zinc can attach to tetracyclines in the stomach. This decreases the amount of tetracyclines that can be absorbed. Taking zinc with tetracyclines might decrease the effectiveness of tetracyclines. To avoid this interaction take zinc 2 hours before or 4 hours after taking tetracyclines.Some tetracyclines include demeclocycline (Declomycin), minocycline (Minocin), and tetracycline (Achromycin).

Cisplatin (Platinol-AQ) interacts with ZINC

Cisplatin (Platinol-AQ) is used to treat cancer. Taking zinc along with EDTA and cisplatin (Platinol-AQ) might increase the effects and side effects of cisplatin (Platinol-AQ).

Penicillamine interacts with ZINC

Penicillamine is used for Wilson's disease and rheumatoid arthritis. Zinc might decrease how much penicillamine your body absorbs and decrease the effectiveness of penicillamine.

Minor Interaction Be watchful with this combination

Amiloride (Midamor) interacts with ZINC

Amiloride (Midamor) is used as a "water pill" to help remove excess water from the body. Another effect of amiloride (Midamor) is that it can increase the amount of zinc in the body. Taking zinc supplements with amiloride (Midamor) might cause you to have too much zinc in your body.

The following doses have been studied in scientific research:

BY MOUTH: For treating the common cold: one zinc gluconate or acetate lozenge, providing 9-24 mg elemental zinc,

dissolved in the mouth every two hours while awake when cold symptoms are present.

For diarrhea in malnourished or zinc-deficient children: 10-40 mg elemental zinc daily.

For preventing and treating pneumonia in undernourished children in developing countries: 10-70 mg/day.

For hypogeusia (sense of taste is abnormal): 25-100 mg zinc.

For the eating disorder anorexia nervosa: 100 mg of zinc gluconate daily.

For treating stomach ulcers: zinc sulfate 200 mg three times daily.

For muscle cramps in zinc deficient people with liver disease: zinc sulfate 220 mg twice daily.

For osteoporosis: 15 mg zinc combined with 5 mg manganese, 1000 mg calcium, and 2.5 mg copper has been used.

For sickle cell disease: zinc sulfate 220 mg three times daily.

To increase growth and weight gain in children with sickle cell disease who have not reached puberty: 10 mg elemental zinc per day.

For treating attention deficit-hyperactivity disorder (ADHD) in children: doses of zinc sulfate 55 mg (15 mg elemental zinc) to 150 mg (40 mg elemental zinc) daily.

For treating acne: 30-135 mg elemental zinc daily.

For treating age-related macular degeneration (AMD): elemental zinc 80 mg plus vitamin C 500 mg, vitamin E 400 IU, and beta-carotene 15 mg daily.

The Institute of Medicine has established Adequate Intake (AI) levels of zinc for infants birth to 6 months is 2 mg/day. For older infants, children, and adults, Recommended Dietary Allowance (RDA) quantities of zinc have been established: infants and children 7 months to 3 years, 3 mg/day; 4 to 8 years, 5 mg/day; 9 to 13 years, 8 mg/day; girls 14 to 18 years, 9 mg/day; boys and men age 14 and older, 11 mg/day; women 19 and older, 8 mg/day; pregnant women 14 to 18, 13 mg/day; pregnant women 19 and older, 11 mg/day; lactating women 14 to 18, 14 mg/day; lactating women 19 and older, 12 mg/day.

The typical North American male consumes about 13 mg/day of dietary zinc; women consume approximately 9 mg/day.

The Tolerable Upper Intake Levels (UL) of zinc for people who are not receiving zinc under medical supervision: Infants birth to 6 months, 4 mg/day; 7 to 12 months, 5 mg/day; children 1 to 3 years, 7 mg/day; 4 to 8 years, 12 mg/day; 9 to 13 years, 23 mg/day; 14 to 18 years (including pregnancy and lactation), 34 mg/day; adults 19 years and older (including pregnancy and lactation), 40 mg/day.

Different salt forms provide different amounts of elemental zinc. Zinc sulfate contains 23% elemental zinc; 220 mg zinc sulfate contains 50 mg zinc. Zinc gluconate contains 14.3% elemental zinc; 10 mg zinc gluconate contains 1.43 mg zinc.

APPLIED TO THE SKIN: For acne vulgaris: zinc acetate 1.2% with erythromycin 4% as a lotion applied twice daily.

For herpes simplex infections: zinc sulfate 0.25% applied 8 to 10 times daily or zinc oxide 0.3% with glycine applied every 2 hours while awake.

zinc

What can high-zinc foods do for you?

Help balance blood sugar Stabilize your metabolic rate Prevent a weakened immune system Support an optimal sense of smell and taste

What events can indicate a need for more high-zinc foods?

Impaired sense of taste or smell Lack of appetite Depression Growth failure in children Frequent colds and infections

Calf's liver is an excellent source of zinc while very good sources of zinc include crimini mushrooms, shiitake mushrooms, venison, and spinach.

World's Healthiest Foods rich inzinc

FoodCals%Daily Value

Venison21765.3%

Lamb22930.6%

Beef, grass-fed17527.2%

Scallops12722.6%

Sesame Seeds20618.6%

Pumpkin Seeds18016.8%

Oats16615.6%

Yogurt15414.5%

Turkey15313.1%

Shrimp11211.8%

For serving size for specific foods, see Nutrient Rating Chart below at the bottom of this page.

Description Function Deficiency Symptoms Toxicity Symptoms Cooking, storage and

processing Factors that affect function

Nutrient interaction Health conditions Food Sources Public Health

Recommendations References

Description

What is zinc?

Zinc is a micromineral needed in the diet on a daily basis, but only in very small amounts (50 milligrams or less). The other microminerals that all humans must get from food are arsenic, boron, cobalt, copper, chromium, fluorine, iodine, iron,manganese, molybdenum, nickel, silicon, vanadium, and zinc.

The first research studies to demonstrate the zinc's important in the diet focused on the issue of growth. When foods did not supply sufficient amounts of zinc, young men in Iran and Egypt were found to have impaired overall growth as well as impaired sexual maturation. These initial studies on zinc reflected some of the key functions served by this mineral, including regulation of genetic activity and balance of carbohydrate metabolism and blood sugar.

How it Functions

What is the function of zinc?

Regulating genetic activities

Zinc is an important regulator of many genetic activities. The cells of our body each have a special compartment called the nucleus, and inside the nucleus are approximately 100,000 genes. These genes provide instructions for the cell, and the cell has to decide which instructions to read. Zinc is essential for reading genetic instructions, and when diets do not contain foods rich in zinc, instructions get misread, or not read at all. (In biochemistry terms, the gene-reading process that requires zinc is called gene transcription.)

Supporting blood sugar balance and metabolic rate

Insulin, a hormone made by the pancreas, is often required to move sugar from our bloodstream into our cells. The response of our cells to insulin is called insulin response. When the foods in our diet do not provide us with enough zinc, insulin response decreases, and our blood sugar becomes more difficult to stabilize. Metabolic rate - the rate at which we create and use up energy - also depends on zinc for its regulation. When zinc is deficient in the diet, metabolic rate drops (along with hormonal output by our thyroid gland).

Supporting smell and taste sensitivity

Gustin is a small protein that is directly involved in our sense of taste. Zinc mus be linked to gustin in order for our sense of taste to function properly. Because of this relationship between zinc and taste, and because taste and smell are so closely linked in human physiology, impaired sense of taste and smell are common symptoms of zinc deficiency.

Supporting immune function

Many types of immune cells appear to depend upon zinc for optimal function. Particularly in children, researchers have studied the effects of zinc deficiency (and zinc supplementation) on immune response and number of white blood cells, including specific studies on T lymphocytes, macrophages, and B cells (all types of white blood cells). In these studies, zinc deficiency has been shown to compromise white blood cells numbers and immune response, while zinc supplementation has been shown to restore conditions to normal.

Deficiency Symptoms

What are deficiency symptoms for zinc?

Because of the link between zinc and the taste-related protein called gustin, impaired sense of taste and/or smell are common symptoms of zinc deficiency.

Depression, lack of appetite, growth failure in children, and frequent colds and infections can also be symptomatic of insufficient dietary zinc.

Toxicity Symptoms

What are toxicity symptoms for zinc?

Zinc toxicity has been reported in the research literature, and in 2000 the National Academy of Sciences set a tolerable upper limit (UI) of 40 milligrams for daily intake of zinc. (This limit applies to all individuals age 19 and over.) A metallic, bitter taste in the mouth can be indicative of zinc toxicity, as can stomach pain, nausea, vomiting, cramps, and diarrhea mixed with blood.

Impact of Cooking, Storage and Processing

How do cooking, storage, or processing affect zinc?

Like most minerals, zinc is present in many different forms in food, and can vary greatly in its response to cooking and processing. In some foods, where a greater percent of zinc is found in water-soluble form and contact with water is great, high losses of zinc can occur.

For example, when navy beans are cooked, 50% of the original zinc is lost. The processing of wheat is another example of the susceptibility of zinc to substantial loss. In 60% extraction wheat flour - the kind that is used to make over 90% of all breads, baked goods, and pastas sold in the U.S., almost 75% of the original zinc is lost.

Factors that Affect Function

What factors might contribute to a deficiency of zinc?

In addition to dietary deficiency, problems in the digestive tract can contribute to zinc deficiency. These problems include irritable and inflammatory bowel disorders, as well as insufficient output by the pancreas that prevents proper digestion of food.

Protein deficiency, and deficiency of one particular part of protein—the amino acid cysteine—can also contribute to zinc deficiency by preventing synthesis of transport and storage molecules that are used to shuttle and store zinc in the body.

Loss of zinc through chronic diarrhea or profuse sweating (as might occur with heavy physical labor or athletic training) can also contribute to deficiency of this mineral.

Nutrient Interactions

How do other nutrients interact with zinc?

A Tolerable Upper Limit (UL) for zinc of 40 milligrams per day was set by the National Academy of Sciences in 2000 for all adults 19 years and older. The establishment of this limit was largely related to the ability of zinc—particularly supplemental zinc—to impair the status of other nutrients.

The most important of these nutrients are copper and calcium. Even at moderate doses of 18-20 milligrams that can easily be obtained from food, zinc can compromise the body's supply of copper unless foods rich in copper are also included in the diet. When few foods high in calcium are included in the diet, high levels of zinc intake (usually obtained from supplements) can also decrease absorption of calcium from the intestine into the body.

Although zinc is associated with these potential detrimental effects on copper and calcium, it is also supportive of other nutrients. The best studied of these nutrients in vitamin A. Without zinc, vitamin A cannot be effectively transported around the body, and cannot efficiently be mobilized when it is needed.

Health Conditions

What health conditions require special emphasis on zinc?

Zinc may play a role in the prevention and/or treatment of the following health conditions:

Acne Alcoholism Alopecia Alzheimer's disease Anorexia nervosa Atopic dermatitis Benign prostatic hypertrophy Cervical dysplasia Common cold Crohn's disease Diabetes Epilepsy Graves' disease Herpes simplex HIV/AIDS Infertility (male) Inflammatory bowel diseases Influenza Macular degeneration Osteoarthritis

PMS Psoriasis Rheumatoid arthritis Seborrheic dermatitis Senile cataracts

Food Sources

What foods provide zinc?

Calf's liver is an excellent source of zinc. Crimini mushrooms, shiitake mushrooms, spinach, and venison are very good sources of zinc.

Good sources include asparagus, chard, scallops, lamb, beef, maple syrup, shrimp, green peas, yogurt, oats, pumpkin seeds, sesame seeds, turkey, miso, and spelt.

 

Introduction to Nutrient Rating System Chart

In order to better help you identify foods that feature a high concentration of nutrients for the calories they contain, we created a Food Rating System. This system allows us to highlight the foods that are especially rich in particular nutrients. The following chart shows the World's Healthiest Foods that are either an excellent, very good, or good source of zinc. Next to each food name, you'll find the serving size we used to calculate the food's nutrient composition, the calories contained in the serving, the amount of zinc contained in one serving size of the food, the percent Daily Value (DV%) that this amount represents, the nutrient density that we calculated for this food and nutrient, and the rating we established in our rating system. For most of our nutrient ratings, we adopted the government standards for food labeling that are found in the U.S. Food and Drug Administration's "Reference Values for Nutrition Labeling."Read more background information and details of our rating system.

World's Healthiest Foods ranked as quality sources ofzinc

FoodServing

Size CalsAmount

(mg)DV(%)

Nutrient

Density

World'sHealthiest

Foods Rating

Venison 4 oz-wt 216.6 9.80 65.3 5.4 very good

Spinach 1 cup 41.4 1.37 9.1 4.0 very good

cooked

Mushrooms - Crimini 1 cup 19.1 0.96 6.4 6.0 very good

Mushrooms, Shiitake

87 g 29.6 0.90 6.0 3.7 very good

Lamb 4 oz-wt 229.1 4.60 30.7 2.4 good

Beef, grass-fed 4 oz 175.0 4.09 27.3 2.8 good

Scallops 4 oz-wt 127.0 3.40 22.7 3.2 good

Sesame Seeds 0.25 cup 206.3 2.79 18.6 1.6 good

Pumpkin Seeds 0.25 cup 180.3 2.52 16.8 1.7 good

Oats1 cup

cooked166.1 2.34 15.6 1.7 good

Yogurt 1 cup 154.3 2.18 14.5 1.7 good

Turkey 4 oz-wt 153.1 1.97 13.1 1.5 good

Shrimp 4 oz-wt 112.3 1.77 11.8 1.9 good

Green Peas 1 cup raw 115.7 1.64 10.9 1.7 good

Asparagus 1 cup raw 26.8 0.72 4.8 3.2 good

Swiss Chard1 cup

cooked35.0 0.58 3.9 2.0 good

Maple Syrup 2 tsp 34.8 0.55 3.7 1.9 good

Miso 1 tbs 34.2 0.44 2.9 1.5 good

World's HealthiestFoods Rating Rule

excellentDV>=75% OR

Density>=7.6 AND DV>=10%

very goodDV>=50% OR

Density>=3.4 AND DV>=5%

goodDV>=25% OR

Density>=1.5 AND DV>=2.5%

Public Health Recommendations

What are current public health recommendations for zinc?

The Recommended Dietary Allowances for zinc, set in 1999 by the Institute of Medicine at the National Academy of Sciences, are as follows:

Males and females, 0-6 months: 2 milligrams Males and females, 6-12 months: 3 milligrams Males and females, 1-3 years: 3 milligrams Males and females, 4-8 years: 5 milligrams Males and females, 9-13 years: 8 milligrams Males 14 years and older: 11 milligrams Females 14-18 years: 9 milligrams Females 19 years and older: 8 milligrams Pregnant females 18 years or younger: 12 milligrams Pregnant females 19 years and older: 11 milligrams Lactating females 18 years or younger: 13 milligrams Lactating females 19 years and older: 12 milligrams

The National Academy of Sciences set a tolerable upper limit (UI) of 40 milligrams for daily intake of zinc. (This limit applies to all individuals age 19 and over.) For more details on this, see the Toxicity Symptoms section above.

References

Cerhan JR, Saag KG, Merlino LA et al. Antioxidant micronutrients and risk of rheumatoid arthritis in a cohort of older women. Am J Epidemiol. 2003 Feb 15; 157(4):345-54. 2003.

Chandra RK. Micronutrients and immune functions. Ann NY Acad Sci 1990;587:9-16. 1990.

Dunn MA, Blalock TL, Cousins RJ. Metallothionein. Proc Soc Exp Biol Med 1987;187:107-119. 1987.

Festa MD, Anderson HL, Dowdy RP, et al. Effect of zinc intake on copper excretion and retention in men. Am J Clin Nutr 1985;41:285-292. 1985.

Forbes RM, Erdman JW Jr. Bioavailability of trace mineral elements. Ann Rev Nutr 1983;2:213-231. 1983.

Groff JL, Gropper SS, Hunt SM. Advanced Nutrition and Human Metabolism. West Publishing Company, New York, 1995. 1995.

Hambridge KM, Casey CE, Krebs NF. Zinc. In: Mertz W. (Ed), Trace elements in human and animal nutrition. 5th Edition, Volume 2. Academic Press, Orlando, Florida, 1986. 1986.

Meiners CR, Derise NL, Lau HC, et al. (1976). The content of nine mineral elements in raw and cooked mature dry legumes. J Arg Food Chem 1976;24:1126-1130. 1976.

National Research Council. Recommended Dietary Allowances, 10th ed. Washington, DC: National Academy Press; 1989. 1989.

Pedersen B, Eggum BO. The influence of milling on the nutritive value of flour from cereal grains. Part 2. Wheat. Qual Plant Plant Fds Hum Nutr 1983;33:51-61. 1983.

Prasad AS, Cavdar AO, Brewer GJ, et al. Zinc deficiency in human subjects. Alan R Liss, Inc, New York, 1983. 1983.

Smith JC Jr, McDaniel EG, Fan FF, et al. Zinc: a trace element in vitamin A metabolism. Science 1973;181:954. 1973.

Solomons NW, Cousins RJ. Zinc. In: Solomons NW and Rosenberg IH. (Eds). Absorption and malabsorption of mineral nutrients. Alan R Liss, New York, 1984. 1984.

Spencer H. Minerals and mineral interactions in human beings. J Am Diet Assoc 1986;86:864-867. 1986.

Wada L, King JC. Effect of low zinc intakes on basal metabolic rate, thyroid hormones and protein utilization in adult men. J Nutr 1986;116:1045-1053. 1986.

Wu FY-H, Wu C-W. Zinc in DNA replication and transcription. Ann Rev Nutr 1987;7:251-272. 1987.

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inc is an essential mineral required by the body for maintaining a sense of smell, keeping a healthy immune system, building proteins, triggering enzymes, and creating DNA. Zinc also helps the cells in your body communicate by functioning as a neurotransmitter. A deficiency in zinc can lead to stunted growth, diarrhea, impotence,

hair loss, eye and skin lesions, impaired appetite, and depressed immunity. Conversely, consuming too much zinc can lead to nausea, vomiting, loss of appetite, abdominal cramps, diarrhea, and headaches in the short term, and can disrupt absorption of copper and iron in the long term. If you have a zinc deficiency, then animal foods are better sources of zinc than plant foods. The current percent daily value (%DV) for Zinc is 15mg. Below is a list of the top ten foods highest in Zinc.

#1: Oysters 

Depending on type and variety oysters provide 16-182mg of zinc per

100g serving. This accounts for 110%-1200% of the DV for zinc. The food highest in

zinc is The Steamed Wild Eastern Oyster which provides 182 mg of zinc per 100g

serving, or 76mg (509% DV) in 6 oysters, and 154mg (1029% DV) in a 3 ounce serving.

Click to see complete nutrition facts.

#2: Toasted Wheat Germ 

Packed in jars and sold toasted, wheat germ is great to sprinkle on top of

any food. Try it on salads, rice, or steamed vegetables. Toasted wheat germ provides

17mg (112% DV) of zinc per 100g serving, which is 19mg (126% DV) per cup, and

1.2mg (8% DV) in a single tablespoon. Crude (untoasted) wheat germ provides 12mg

(82% DV) of zinc per 100g serving, 14mg (94% DV) per cup, and 1mg (6% DV) per

tablespoon. Click to see complete nutrition facts. Buy Wheat Germ from Amazon.com

#3: Veal Liver 

The liver of any animal is packed with vitamins and minerals and most

commonly served as pâté or liverwurst. Veal liver has the most zinc with 12mg per 100g

serving accounting for 81% of the DV, that is 8.98mg of zinc (60% DV) in a cooked slice

of liver (80g). Liver is best prepared steamed or fried with onions and herbs. 

Click to see complete nutrition facts.

#4: Low Fat Roast Beef 

Low fat beef shoulder, shank, and chuck all contain about 10mg (70%

DV) of zinc per 100g serving, 18mg (119% DV) per pound, and 9mg (59% DV) in a 3 oz

serving. If you buy pre-processed roast beef be sure to consult the nutrition facts about

the cut and nutrients. Not all nutrition labels report zinc, so don't worry if you don't see

it. 

Click to see complete nutrition facts.

#5: Roasted Pumpkin and Squash Seeds 

A popular food in the Middle East and East Asia pumpkin and squash

seeds contain about 10mg (70% DV) of zinc per 100g serving, 6.6mg (59% DV) per

cup, and 3mg (19% DV) per ounce (~85 seeds). If you can't find these in your local

supermarket you will surely find them in Middle Eastern or East Asian specialty stores.

Alternatively, you can also save any pumpkin and squash seeds you have and roast

them in your oven. The seeds are typically eaten by cracking the outer shell and eating

the seed inside. 

Click to see complete nutrition facts. Seeds and Nuts with the Fewest Calories.

#6: Dried Watermelon Seeds 

Much like the pumpkin and squash, watermelon seeds are popular in the

Middle East and East Asia and they should be in specialty stores catering to those

cultures. It is also possible to just eat the seeds raw with the watermelon. You can shell

them, or just chew them up whole. Dried watermelon seeds provide 10mg (70% DV) of

zinc per 100g serving, 11mg (74 %DV) per cup, and 3mg (19% DV) per ounce. 

Click to see complete nutrition facts.

#7: Dark Chocolate and Cocoa Powder 

Chocolate is showing more and more health benefits and dark chocolate

is coming into vogue. Unsweetened baking chocolate provides 9.6mg (64% DV) of zinc

per 100g serving (most bars are 50-100 grams). Cocoa powder will provide 6.8mg (45%

DV) per 100g, or 5.4mg (39% DV) per cup, 0.3mg (2% DV) per tablespoon. Most milk

chocolates provide around 2.3mg (15% DV) per 100g serving or 1mg (7% DV) per

bar. Click to see complete nutrition facts. Buy Dark Chocolate from Amazon.com

#8: Lamb (Mutton) 

Lamb is a common meat in the Middle East, Mediterranean, and most of

Europe, but is increasing in popularity in the Americas. Lamb provides between 4.2-

8.7mg of zinc per 100g serving (28%-58% DV) depending on cut. That is up to 7.4mg

(49% DV) in a 3 ounce serving (85 grams). 

Click to see complete nutrition facts.

#9: Peanuts 

Peanuts are a great source of zinc, 100 grams of oil roasted peanuts will

provide 6.6mg (44% DV) of zinc, or 8.8mg (59% DV) in 1 cup chopped, 1.9mg (12%

DV) per oz (~39 peanuts). Dry roasted peanuts will provide half as much zinc at 3.3mg

(22% DV) per 100 gram serving, or 4.8mg (32% DV) per cup, and 1mg (6% DV) per oz. 

Click to see complete nutrition facts. Buy Peanuts from Amazon.com

#10: Crab 

Almost any kind of crab will be a great source of zinc. Alaksa King crab in

particular provides 7.6mg (51% DV) of zinc per 100 gram serving, which is 10.2mg

(68% DV) in an average crab leg, and 6.5mg (43% DV) in a 3 ounce serving. Click to see

complete nutrition facts.

Other Zinc Rich Foods

Alaska King

Crab

7.6mg (51%

DV) per 100

gram serving

10.2mg (68% DV)

per leg (134

grams)

6.5mg (43% DV) per

3oz serving (85

grams)

Click to see complete

nutrition facts for Alaska

King Crab

Pork (Shoulder)

5mg (33% DV)

per 100 gram

serving

7.4mg (49% DV)

per steak(147

grams)

4.2mg (28% DV) per

3oz serving (85

grams)

Click to see complete

nutrition facts for Pork

Shoulder

Fortified Cereals

(Varies By

Brand)

52mg (345%

DV) per 100

gram serving

15.5mg (103% DV) per cupClick to compare nutrition

facts for various cereals

Chicken Leg

(Roasted)

2.9mg (19%

DV) per 100

gram serving

2.7mg (18% DV)

per leg(95 grams)

4mg (27% DV) per

cup (140 grams)

Click to see complete

nutrition facts for Chicken

Legs

Pork Tenderloin

3mg (20% DV)

per 100 gram

serving

2.2mg (14% DV)

per chop (73

grams)

2.5mg (17% DV) per

3oz serving(85

grams)

Click to see complete

nutrition facts for Pork

Tenderloin

Lobster

2.9mg (19%

DV) per 100

gram serving

4.2mg (28% DV)

per cup (145

grams)

2.5mg (17% DV) per

3oz serving(85

grams)

Click to see complete

nutrition facts for Cooked

Lobster

Baked Beans 1.4mg (9% DV) 3.5mg (24% DV) per cup (253 grams) Click to see complete

per 100 gram

serving

nutrition facts for Baked

Beans

Dry Roasted

Cashews

5.6mg (37%

DV) per 100

gram serving

7.7mg (51% DV)

per cup (137

grams)

1.6mg (10% DV) per

1oz serving(28

grams)

Click to see complete

nutrition facts for Dry

Roasted Cashews

Low Fat Yogurt

with Fruit

0.7mg (4% DV)

per 100 gram

serving

1.6mg (11% DV)

per cup (245

grams)

0.8mg (5% DV) per

1/2 cup (113 grams)

Click to see complete

nutrition facts for Low Fat

Yogurt with Fruit

Chickpeas

(Garbanzo

Beans)

1.5mg (10%

DV) per 100

gram serving

2.5mg (17% DV)

per cup (164

grams)

1.3mg (9% DV) per

1/2 cup (82 grams)

Click to see complete

nutrition facts for

Chickpeas (Garbanzo

Beans)

Almonds

3.5mg (24%

DV) per 100

gram serving

4.9mg (33% DV)

per cup (138

grams)

1mg (7% DV) per 1

ounce serving (28

grams)

Click to see complete

nutrition facts for

Almonds

Milk

0.4mg (3% DV)

per 100 gram

serving

1mg (7% DV) per

cup (244 grams)

3.9mg (26% DV) per

1 quart serving (976

grams)

Click to see complete

nutrition facts for Milk

Chicken Breast

1mg (7% DV)

per 100 gram

serving

1.4mg (9% DV) per

cup (140 grams)

0.9mg (6% DV) for

half a chicken breast

(86 grams)

Click to see complete

nutrition facts for Chicken

Breast

Cheddar Cheese

3.1mg (21%

DV) per 100

gram serving

3.5mg (23% DV)

per cup (113

grams)

0.9mg (6% DV) per

ounce(oz) (28

grams)

Click to see complete

nutrition facts for

Cheddar Cheese

Mozzarella

2.9mg (19%

DV) per 100

gram serving

3.3mg (22% DV)

per cup (112

grams)

0.8mg (5% DV) per

ounce(oz) (28

grams)

Click to see complete

nutrition facts for

Mozzarella

Kidney Beans

1mg (7% DV)

per 100 gram

serving

1.9mg (13% DV)

per cup (177

grams)

0.1mg (1% DV) per

tablespoon (11

grams)

Click to see complete

nutrition facts for Kidney

Beans

Green Peas 1.2mg (8% DV)

per 100 gram

1.9mg (13% DV)

per cup (160

1.5mg (6% DV) per

half cup (80 grams)

Click to see complete

nutrition facts for Green

serving grams) Peas

Sesame Seeds

(Tahini)

10.5mg (70%

DV) per 100

gram serving

1.5mg (10% DV)

per tablespoon (14

grams)

2.9mg (20% DV) per

1 ounce serving (28

grams)

Click to see complete

nutrition facts for Sesame

Seeds (Tahini)

Flat Fish

(Flounder or

Sole)

0.6mg (4% DV)

per 100 gram

serving

0.8mg (5% DV) per

fillet (127 grams)

0.5mg (4% DV) per 3

ounce serving (85

grams)

Click to see complete

nutrition facts for Flat

Fish (Flounder or Sole)

Health Benefits of Zinc

Healthy Immune Function - Even mild to moderate zinc deficiency can depress

the immune system through impaired macrophage and neutrophil functions, and

associated effects.3 Zinc is also essential for creation and activation of T-

lymphocytes.4,5 Further, low levels of zinc have been associated with increased

susceptibility to pneumonia and other infections in children and the elderly.6-9

Alleviation of the Common Cold (*Controversial) - There are conflicting

studies as to weather or not zinc supplements can alleviate symptoms of the

common cold and shorten its duration. At least one study confirms decreased

duration of cold symptoms compared to a control,10 however, other studies report

no effect.11,12 Since no harm is reported, increasing zinc intake could only help.

Healing of Cuts and Wounds - Zinc is essential for healthy skin and

maintenance of mucosal membranes. Adequate levels of zinc is necessary for

proper wound healing.13

Reduced Severity and Duration of Diarrhea - Studies show that increased

intake of zinc can reduce duration and severity of diarrhea in undernourished

children with infections.14-17

Prevention and Reduction of Age-Related Eye Damage - High dietary intake

of zinc, as well as vitamins C, E, and beta-carotene, has been associated with

reduced age-related macular deneration in the edlerly.18

High Risk Groups for a Zinc Deficiency

Alcoholics - 30-50% of alcoholics have low levels of zinc because alcohol

decreases zinc absorption and increases urinary secretion of zinc.

Vegetarians - The bio-availability of zinc is higher in meats and thus more easily

absorbed. Further legumes and whole grains contain phylates which bind zinc

and inhibit absorption. (See lists of fruits and vegetables high in zinc.)

Pregnant and Lactating Women - A developing fetus requires a high amount of

zinc, likewise, there is a high amount of zinc lost through breast milk after birth.

Older Infants who are Exclusively Breastfed - Infants older than 6 months

should eat age-appropriate foods which provide zinc as the amount in breast milk

is no longer ample.

People with Sickle Cell Disease - For unknown reasons 44% of children, and

60-70% of adults with sickle cell disease have low levels of zinc.

People with Gastrointestinal and Other Diseases - Gastrointestinal surgery,

Crohn's disease, ulcerative colitis, short bowel syndrome, and other digestive

diseases can all decrease zinc absorption and increase zinc loss from the body.

People consuming high doses of Iron Supplements - Iron can interfere with

zinc absorption, to reduce this effect, iron suppliments should be taken between

meals to allow time for zinc to be absorbed properly.

People taking Diuretics - Thiazide diuretics such as chlorthalidone (Hygroton®)

and hydrochlorothiazide (Esidrix® and HydroDIURIL®) can increase zinc

excretion by 60%, and over the long term, deplete body tissues of zinc stores. Be

sure to consult your doctor or clinician to monitor your zinc level if you are taking

these diuretics for a sustained period of time, and be sure to eat more zinc rich

foods.

Recipes High in Zinc

Buckwheat (How to Cook Buckwheat)

Teff (How to Cook Teff)

Blackberry Salad

Warnings

Oysters, liver, lamb, and cheese are high cholesterol foods which should be

eaten in moderate amounts and avoided by people at risk of heart disease or

stroke.

Sesame Seeds, Pumpkin Seeds, Squash Seeds, and Peanuts are high calorie

foods and should be eaten in moderate amounts by people with a high body

mass index.

Zinc suppliments have adverse reactions with the following medications:

o Antibiotics - Certain antibiotics like quinolone antibiotics (such as Cipro®)

and tetracycline antibiotics (such as Achromycin® and Sumycin®) inhibit

the absorption of zinc in the digestive tract.

o Penicillamine - Zinc reduces the absorption of Penicillamine, which is used

by people suffering from rheumatoid arthritis. Taking zinc suppliments two

hours before or after intake of Penicillamine solves this problem.

Read more at http://www.healthaliciousness.com/articles/zinc.php#1K38W07A62UvJkri.99 

nc is so important because it is found in every tissue in the body and is directly involved in cell division. It is a powerful antioxidant, helping to prevent cancer, but zinc also is directly involved in proper endocrine function and the maintenance of ideal hormone levels. 

Zinc deficiency makes both men and women infertile and causes low libido. Low zinc also exacerbates the effects of stress on the body and accelerates aging.  Additionally, adequate zinc is necessary for optimal physical performance, energy levels, and body composition. Zinc affects protein synthesis and is required for proper function of red and white blood cells. It is highly concentrated in our bones, the pancreas, kidneys, liver, and retina. 

This article will give you the top ten reasons why you should attend to your zinc levels and ensure your loved ones are doing so as well. Be aware that zinc deficiency is not only prevalent in malnourished individuals or developing countries. Rather, it is widespread in the U.S. and the UK, and it is particularly common in areas where the population eats a large amount of cereal and grain proteins. Low zinc is common in men, women, and children, and I’ve found that over 90 percent of my clients and athletes are zinc deficient.

Groups At Greatest Risk of Low ZincZinc deficiency occurs from not eating enough zinc-rich foods. Zinc is found in large concentrations in

meat, some seafood—oysters contain the largest concentration of all known foods—and dairy. Whole grains and legumes contain zinc, but it is bound to phytates in these plant-based foods, making the zinc inaccessible by the body. Vegetarians are at greatest risk of zinc deficiency, but alcoholics and people with digestive issues and poor stomach acid are also highly susceptible. Taking medications may produce zinc deficiency and low levels of almost all essential nutrients. Women on the birth control pill or on hormone replacement therapy are at greater risk of deficiency. 

Symptoms of Zinc DeficiencyLow zinc will produce an altered sense of taste leading to cravings of saltier, sweeter food. Deficiency can also be indicated by diarrhea, low energy, chronic fatigue, infertility, poor immunity, bad memory,  inability to focus, ADD symptoms, slow wound healing, nerve dysfunction, and ringing in the ears. Take note that symptoms may be present, but because they are so diverse and associated with other health conditions, it’s often hard to make the link to zinc deficiency without a test. A guide is provided at the end of this article on how to test your zinc level. 

#1 Improve Athletic Performance and StrengthAdequate zinc directly affects athletic performance and strength development from training because it plays a primary role in anabolic hormone production.  Research shows having ample zinc available in the body allows for a more robust release of the three most important anabolic hormones, testosterone, growth hormone and insulin-like growth factor-1 (IGF-1). Without these, you’ll miss out on muscle and strength development from your hard work in the gym. 

Tumar / Shutterstock.com

A recent study in the journal Biological Trace Element Research highlights the boost that raising zinc levels can give to testosterone production following exercise. Researchers found that giving trained athletes a zinc supplement for four weeks prior to an exhaustive exercise test resulted in a greater post-workout testosterone response than a placebo. Taking zinc produced higher testosterone levels in the athletes than taking a selenium supplement (a powerful antioxidant that minimizes oxidative stress in the testis). Researchers note that zinc enhances the conversion rate of androstenedione to testosterone, and that paired with high-intensity exercise, it allows the body to produce testosterone at an even higher rate.

Male and female athletes will benefit from adequate zinc since this mineral ensures healthy release of growth hormone and IGF-1, which are essential for performance and muscle development in both sexes. Plus, the boost to testosterone post-workout can improve strength gains recovery in men. And, as you’ll see below, having enough zinc will give you more energy and improve metabolism. 

#2 Support Male Reproductive Health and FertilityZinc is a critical mineral for robust testosterone levels, and the cells of the male prostate require a very high concentration of zinc to work optimally. Low zinc in men impairs testosterone production, puts them

at risk for developing prostate cancer, and causes infertility. Inadequate zinc has also been linked to low libido. 

One recent study of 88 men aged 40 to 60 years showed that those with normal testosterone levels had significantly higher zinc compared to those with low testosterone levels. Low zinc was directly correlated with low testosterone levels, which put the men at greater risk of symptoms of male menopause. 

Just as important, zinc is used to produce enzymes that initiate cell division, but the male prostate tissue requires ten times more zinc than other cells in the body to stay healthy. Adequate zinc level in the prostate protects the cells from damage, inflammation, and cancer development. Also, once the prostate cells are damaged and become cancerous, they lack the ability to accumulate zinc, leading to greater propagation of cancer cells that produce to tumors.  

Giving a large dose of therapeutic zinc to rats with prostate cancer halted cancer cell proliferation and helped the rats maintain body weight, which is an indicator of better overall health and homeostasis. There was reduced evidence of biomarkers that indicate oxidative stress and inflammation in the prostate from the zinc supplement. Overall enzyme levels were better. In contrast, a placebo group had a rapid increase in cancer cell growth and decrease in body weight. There was also a 50 percent increase in DNA damage and inflammation during the study period, indicating a progressively diseased prostate cancer state.

Researchers write that zinc is a “promising anti-cancer treatment” and that regular supplementation when men are healthy with no evidence of cancer is the best prevention. They also suggest zinc can prevent related cancers such as ovarian, breast, and colorectal. 

#3 Support Female Reproductive Health and FertilityIn women, zinc is involved in the growth process of the oocyte or egg. If women are zinc deficient, the egg won’t mature properly and ovulation will be impeded, causing infertility. Adequate zinc allows women to use estrogen and progesterone efficiently, supporting reproductive health and ensuring that estrogen does what it’s supposed to do in the body. When estrogen levels become too high, or are inefficiently metabolized they can cause poor reproductive health and breast cancer.

#4 Prevent Cancer and Boost Immune FunctionAnanda Prasad, a leading researcher in the field of zinc and health, notes that simply ensuring our zinc levels are adequate can help cure a number of the most severe health problems, especially cancer and poor immune function. Along with prostate cancer, low zinc plays a role in the development of most cancers since it is instrumental in healthy cell proliferation. Recent evidence links zinc deficiency to cancers of the breast, colon, ovaries, lungs, skin, and leukemia. 

Zinc deficiency profoundly affects the immune system because low zinc produces a direct and rapid decline in T cell function. T cells elevate the body’s immune system when viruses, bacteria, or challenges to health arise. Older people are at greater risk of zinc deficiency, which is not thought to be solely due to poor dietary intake. There’s evidence that a need for more zinc may increase with age to counter inflammation, support the immune system, and ensure healthy cell function. 

#5 Improve Cardiovascular HealthZinc is vital to maintain the health of cardiovascular cells and the endothelium. The endothelium is the thin layer of cells that lines the blood vessels and plays a major role in circulation. Low zinc can cause a deficiency in the endothelial barrier, which  leads to high cholesterol buildup and inflammation.

Cholesterol and inflammation increase your risk of heart disease. 

Studies show that poor zinc status can amplify the negative cardiovascular effects of a high-fat, high-cholesterol diet, whereas an adequate zinc intake will have a protective effect and inhibit the progression of heart disease. The elderly population is especially susceptible to the buildup of inflammatory markers including C-reactive proteins and cytokines, which have been called “slow, silent killers.” 

#6 Become More Sensitive to Insulin and Prevent DiabetesZinc is needed for the healthy function of most hormones, including insulin. Adequate zinc plays at least three roles in insulin health. First, zinc binds to insulin so that insulin is adequately stored in the pancreas and released when glucose enters the blood stream.

Second, zinc improves cell health, making up a component of the enzymes necessary for insulin to bind to cells so that glucose can enter and be used as fuel. The process of insulin binding to the cell is what is referred to with the term “insulin sensitivity” and means that the cell is receptive to insulin. Once insulin binds to the cell, it “opens the door” so that the glucose can enter. If the cell is resistant to insulin, glucose will stay in the blood stream, cause high blood sugar, and ultimately lead to fat gain. When zinc concentration falls, there is a reduction in insulin secretion and peripheral insulin sensitivity, which if persistent, will lead to diabetes

Third, zinc has anti-inflammatory effects as mentioned in #5 via its role in abolishing inflammatory markers such as C-reactive proteins. Zinc also helps get rid of substances that cause inflammation in cells, helping to preserve cell health and insulin sensitivity. 

A recent study of Spanish school children found a direct relationship between low zinc levels, greater body fat content, and insulin resistance. The children who were classified as zinc deficient had poorer insulin sensitivity and greater glucose intolerance (a related measurement of persistent blood sugar levels) than those whose level was adequate. 

#7 Get The Super Antioxidant Effects of ZincZinc is an excellent antioxidant. The purpose of an antioxidant is to get rid of free radicals that cause damage to cells in the body by bonding with them and neutralizing them. Zinc is particularly good at countering the damaging effect of high iron. Zinc also targets free radicals that cause inflammation and is especially effective at detoxifying heavy metals from the brain. 

#8 Detoxify The Brain of Heavy Metals and Prevent Alzheimer’sThe super antioxidant effects of zinc allow it to efficiently remove toxins from the body and keep them from building up in tissue and causing damage. The progression of neurodegeneration and Alzheimer’s disease is accelerated by heavy metal buildup in the brain. Zinc can help get rid of those toxins, and it also helps maintain cellular homeostasis of brain cells. 

#9 Boost Brain Function and Treat ADHDZinc plays an essential role in neurotransmitter function and helps maintain brain structure and health. It is necessary in the metabolism of melatonin, which regulates dopamine. Also, zinc is part of an enzyme that is necessary for the anabolism of fatty acids in the brain membrane. This is very important because a key part of supporting brain health and function is to ensure the membrane gets the nutrients it needs. 

A new study on rats tested the effect of giving supplemental zinc to pregnant females during gestation and lactation and found better spatial memory and overall cognitive development in the offspring. A large

zinc dose produced the best results. Human studies are limited, but data on how zinc can treat attention deficit hyperactivity disorder (ADHD) indicate its importance.

Zinc is a commonly ignored mineral for treating ADHD. Studies show children with ADHD tend to have lower zinc than healthy children. Even more promising, one study of 400 children with diagnosed ADHD found that taking 150 mg/d of zinc sulfate improved impaired social behavior and made subjects less hyperactive and impulsive than a placebo. Subjects that had higher body mass index and lower fatty acid level had more dramatic improvements in socialization and hyperactivity measures from taking zinc.

#10 Elevate Mood and Avoid DepressionThe  exact relationship between zinc deficiency and depression is unknown, however it surely has to do with the role of zinc in neurotransmitter and hormone production. Dopamine production, which is partly regulated by zinc status, is a chemical that boosts energy, mood, and reward-driven learning. Poor insulin health or low testosterone levels can lead to health problems that increase rates of depression and low energy. Throw in the antioxidant power of zinc and its ability to get rid of inflammatory biomarkers such as C-reactive protein and tumor necrosis factor (causes cell damage), and it is reasonable to ensure zinc intake is adequate when treating depression. 

A new study in the Journal of Affective Disorders showed that zinc deficiency may affect depression in women more than men. Women in this study who were already using antidepressants and had low zinc levels had a five times greater risk of ongoing depression. It’s thought that the gender-based relationship between low zinc and depression is related to how zinc influences energy levels and production of the hormone estrogen. 

In women, estrogen is involved in serotonin production—the neurotransmitter that makes people feel good—and zinc supplementation can increase the density of serotonin receptors in the brain. Have you picked up on the theme that zinc plays multiple roles in the body, affecting numerous chemical messengers that play complex, essential, interconnected parts in the body?  

How To Test Zinc LevelBefore you start popping zinc at random, take note that there is an upper limit to dietary zinc. Zinc toxicity has produced poor immune health and infertility, just as low zinc compromises the immune system. Scientists suggest you perform a zinc test to measure your level and then supplement accordingly. Once you start taking zinc, your levels will rise and you should do another test six to eight weeks later for best results. 

The simplest way to test for zinc is a taste test that works because we know that taste and smell are dependent on there being adequate zinc in the body. To do this test, get zinc sulfate and put about 1-2 teaspoons in a cup and sip it, holding it in the mouth. If it tastes just like water, you are very zinc deficient. If you taste something slightly metallic, you are moderately zinc deficient. If it tastes disgusting—strongly metallic and unpleasant—your levels are probably adequate. This test is subject to individual taste perception and it is not 100 percent valid, but it is a good place to start.

Other test options are a serum zinc test, but there are factors that can cause inaccuracies such as fluctuations from meals, stress, diurnal variations, and complications from other nutrient deficiencies. A plasma zinc test is another option and it will pick up severe zinc deficiencies, but it won’t indicate a more moderate deficiency. It should not be relied on because even a moderate deficiency will negatively influence health.