Lecture 9 nutrients involved in fluid and electrolyte balance

NDD10103 PRINCIPLES OF HUMAN NUTRITION

Lecture 9: Nutrients Involved In Fluid And Electrolyte Balance

DR. SHARIFAH WAJIHAH WAFA


Topic Learning Outcomes• At the end of this lecture, the student should be able to:

1. Identify four nutrients that function as electrolytes in our bodies.

2. List three functions of water in our bodies.

3. Describe how electrolytes assist in the regulation of healthful fluid balance.

4. Define hyponatremia and identify factors that can cause this condition.

5. Identify four symptoms of dehydration.


Course Outline

• Why Is Water So Important?• Functions of Water in the Body• Water Balance• Electrolytes Participate in Fluid Balance• How Do Water and Sodium Affect Blood

Pressure?


Body Fluids• Body fluid is the liquid portion of cells and

tissues• Characterized by its ability to move freely and

changeably, adapting to the shape of the container that holds it

• About 50−70% of healthy adult body weight


Body Fluids• Intracelluar fluid: within the cell

– 2/3 of body fluid• Extracellular fluid: outside the cell

– 1/3 of body fluid– Interstitial fluid flows between cells that make up a

particular tissue or organ (muscle, liver)– Intravascular fluid is the water in the blood and lymph– Plasma transports blood cells within arteries, veins, and

capillaries

Intracellular and Extracellular Fluid



Body Fluids

• Fluid composition of tissue varies by:– Tissue type: lean tissues have higher fluid content

than fat tissues– Gender: males have more lean tissue and

therefore more body fluid than females– Age: decrease in body water results partly from

loss of lean tissue as people age


Electrolytes

• Dissolved substances that disassociate in solution into electrically charged particles called ions– Positive charge: sodium, potassium– Negative charge: chloride, phosphorus

• Predominant electrolytes– Extracellular fluid: potassium, phosphorus– Intracellular fluid: sodium, chloride

Role of Electrolytes in Water Balance


Functions of Water• Medium for chemical reactions

• Participates in chemical reactions

• Distributes nutrients to cells

• Removes waste products from cells

• Lubricant for joints

• Moistens organs, GI tract, eyes, skin

• Maintains body temperature

• Maintains blood volume


Acid-base balance

Chemical reactions

Lubricant

Distribution of nutrients

Temperature regulation

Removal of waste products

Component of body fluids


21

Water is the Main Constituent of the Body

74 pounds of water (57%)

17 pounds of protein (13%)

32 pounds of fat (25%)

7 pounds of minerals (5%)

1 pound of glycogen (<1%)

105 pounds of water (62%)

27 pounds of protein (16%)

27 pounds of fat (16%)

10 pounds of minerals (6%)

1 pound of glycogen (<1%)

Healthy Man (170 pounds) Healthy Woman (130 pounds)

© Digital Vision / Getty Images RF


Functions of Body Fluids

• Fluids dissolve and transport substances – Water is an excellent solvent because it dissolves a

variety of substances– Water-soluble substances are readily transported

in the bloodstream: amino acids, glucose, vitamins, minerals, medications

– Fatty substances must be attached to or surrounded by water-soluble proteins



• Fluids account for blood volume– Appropriate body fluid levels are essential for

maintaining healthful blood volume– Blood pressure increases when blood volume rises– High blood pressure (hypertension) is a risk factor

for heart disease and stroke– Low blood pressure can cause people to feel tired,

confused, or dizzy – Kidneys help to regulate blood volume and blood

pressure



• Fluids account for blood volume– Antidiuretic hormone (ADH) stimulates the kidneys

to reabsorb water, reducing urine– Renin responds to decreased blood pressure– Angiotensin II (vasoconstrictor) increases blood

pressure– Aldosterone signals the kidneys to retain sodium

and chloride, thereby retaining water, increasing blood pressure, and decreasing urine output




• Fluids help maintain body temperature– Body temperature must be within a safe range– Water has a high capacity for heat, which means

that only sustained high heat can increase body temperature

– Sweating releases heat as the evaporation of water from the skin cools the skin and blood




• Protect and lubricate tissues – Cerebrospinal fluid protects the brain and spinal

cord– Amniotic fluid protects the fetus– Synovial fluid lubricates joints– Tears cleanse and lubricate eyes– Saliva moistens food for swallowing


Functions of Electrolytes

• Electrolytes help regulate fluid balance – Cell membranes are permeable to water, but not

freely permeable to electrolytes – Water moves by osmosis to areas where the

concentration of solute is high– This action provides a means to control movement

of water into and out of the cells– Osmotic pressure keeps electrolytes in solution

from drawing liquid toward them across a semipermeable membrane





• Electrolytes enable nerves to respond to stimuli – Nerve impulses are initiated at nerve cell

membranes in response to a change in electrical charge across the membrane

– Depolarization—Action Potential—Repolarization– Sodium and potassium ensure that nerve impulses

are generated, transmitted, and completed




• Electrolytes signal muscles to contract– Muscles are stimulated to contract in response to

stimulation of nerve cells – Influx of calcium into the muscle from the

extracellular space stimulates contraction– Muscles can relax after contraction once the

electrical signal is complete and calcium is pumped out of the muscle cell


Fluid Balance

• Thirst mechanism (hypothalamus) prompts us to drink when it is stimulated by– Increased concentration of salt and other

dissolved substances in the blood– A reduction in blood volume and blood pressure,

such as during profuse sweating, vomiting, diarrhea, or low fluid intake

– Dry mouth and throat from reduced saliva• ADH signals the kidneys to retain water


Fluid Balance

• Body gains fluids– Water enters the body through beverages– Some foods have very high water content– Water from metabolic reactions contributes

10−14% of daily water need


Fluid Balance

• Sensible water loss– Kidneys excrete water as urine– Sweat during exercise or in hot environment

• Insensible water loss– Skin (not sweating) or lungs during exhalation

• Significant loss– Illness, injury, exercise, high altitude, pregnancy,

breastfeeding, diuretics


Intake 2,500 mL/day

Output 2,500 mL/day

Metabolic water 200 mL

Feces 200 mL

Expired air 300 mL

Cutaneous transpiration

400 mLSweat 100 mL

Urine 1,500 mL

Drink 1,600 mL

Food 700 mL

Fluid Balance


Water

• Water– Essential for life– Amount needed varies with gender, age, body

size, health status, physical activity level, environment

– Sources of drinking water: carbonated, mineral, distilled, purified, tap, bottled

ABC Video Bottled Water




Water

• What happens if we drink too much water?– Becoming overhydrated is rare– Dilution of blood sodium concentration

• What happens if we don’t drink enough water?– Dehydration– Leading cause of death around the world

Water Balance


Sodium (Na+)

• Table salt = sodium chloride = NaC

– 40% sodium– 60% chloride

• 1 tsp of salt = 2,400 mg sodium


Sodium: Functions

• Adds flavor to foods

• Preserves food

• Helps maintain fluid balance

• Helps nerve impulse conduction

• Helps absorption of some nutrients (ex: glucose)


Sodium: Deficiency

• Groups at risk:

– Low sodium diet– Excessive

sweating (ex: athletes)

– Persistent vomiting or diarrhea

• Symptoms:

– Muscle cramps– Nausea and vomiting– Dizziness– Shock– Coma


Sodium: Nutrient Needs

• DRI:– For adults under age 51: 1,300 mg/day– For adults aged 51-70: 1,300 mg/day– For adults aged 71+: 1,200 mg/day

• Average American consumption:– 2,300-4,700 mg/day

• DV on food labels based on:– 2,400 mg/day

• To lower blood pressure:– 2,000 mg/day or less


Sodium Intake

• AI: 1,500 mg• most recommend < 2,300

mg/day• <1,500 mg per day:

– Those with hypertension, diabetes or chronic kidney disease

• The National Heart Lung and Blood Association reports that 500 mg is a safe daily minimum intake of sodium


Food Sources of Sodium

• High sodium foods:

– Packaged foods– Processed foods– Fast food– Canned foods– Frozen, ready

prepared foods (ex: pizza)

• Low sodium foods:

– Fruits & vegetables– Whole grains– Meats w/o sauces– Unprocessed foods


Food Sources of Sodium

* For adults; see the DRI table in the back of this book for age-specific recommendations.

Dairy

Key:

Adult Male and Female AI = 1500 milligrams

Daily Value = 2400 milligrams%AI

Food Item and Amount

Sodium Content

(milligrams)

ChooseMyPlate.gov

AI* 1500 100%

Pepperoni pizza , 2 slices 2045 136%

Ham, sliced, 1 ounce 1215 81%

Chicken noodle soup, canned, 1 cup 1106 74%

V8 vegetable juice, 8 ounces 620 41%

Macaroni salad, ½ cup 561 37%

Hard pretzels, 1 ounce 486 32%

Hamburger with bun, 1 each 474 32%

Green beans, canned, ½ cup 390 26%

Saltine crackers, 6 each 234 16%

Cheddar cheese, 1 ounce 176 12%

Peanut butter, 2 tablespoons 156 10% Grains

Nonfat milk, 1 cup 1278%Vegetables

Seven-grain bread, 1 slice 126 Fruits8%

Animal crackers, 1 ounce 112 7% ProteinGrape juice, 1 cup 10 1%


77%

6%

5%

Added to foods during cooking at home

Added to food at the table

12%

Present in foods naturally

Added to foods during food

processing or in restaurant meals

Sodium in food


Sodium: Excess

• ↑ urine output & can lead to dehydration– Normal 5g excreted daily– Hypertension decreases renin result in

upto 25g excreted daily

• ↑ blood pressure indicates high sodium

• UL: 2,300 mg/day

– Note that the DV (2,400 mg) is > UL– Healthier goal: aim for the AI (1,500 mg)


Potassium

• Potassium– Major positively charged electrolyte in the

intracellular fluid – Together with sodium, maintains fluid balance and

regulates the contraction of muscles and transmission of nerve impulses

– High potassium intake helps maintain a lower blood pressure


Potassium (K): Functions

• Water Balance

• Nerve impulse transmission

• Principal positively charged intracellular ion

• ↑ potassium intake can help ↓ BP


Potassium: Deficiency

• Can be caused from:

– Chronic diarrhea– Vomiting– Laxative abuse– Alcohol abuse– Eating disorders– Very low calorie diets

• Symptoms include:

– Loss of appetite– Muscle cramps– Confusion– Constipation– Irregular heart beat


Potassium: Nutrient Needs

• AI for adults:

– 4,700 mg

• DV used on labels:

– 3,500 mg

• Typical North American consumption:

– 2,000-3,000 mg/day


Food Sources of Potassium

• Unprocessed foods

– Fruits– Vegetables– Milk– Whole grains– Dried beans– meats

• Major contributors in the diet include:

– Milk– Potatoes– Beef– Coffee– Tomatoes– Orange juice


Food Sources of Potassium

* For adults; see the DRI table in the back of this book for age-specific recommendations.

8%

Food Item and Amount

Potassium (milligrams)

Adult Male and Female AI = 4700 milligrams

Daily Value = 3500 milligrams%AI

AI* 4700 100%

Kidney beans, 1 cup 715 15%

Winter squash, ¾ cup 670 14%

Plain yogurt, 1 cup 570 12%

Orange juice, 1 cup 495 11%

Cantaloupe, 1 cup 495 11%

Lima beans, ½ cup 480 10%

Banana, 1 medium 470 10%

Zucchini, 1 cup 450 10%

Soybeans, ½ cup 440 9%

Artichoke, 1 medium 425 9%

Tomato juice, ¾ cup 400

ChooseMyPlate

9% Key:

GrainsPinto beans, ½ cup 400 9%

VegetablesBaked potato, 1 small 385 8%

FruitsButtermilk, 1 cup 370 Dairy

ProteinSirloin steak, 3 ounces 345 7%

.gov


MyPlate: Sources of Potassium

58

MyPlate:Sources of PotassiumChooseMyPlate.go

v

Fruits

VegetablesProtein

Grains• Whole-

wheat bread

• Whole-grain products

Vegetables• Avocados• Spinach• Squash• Potatoes• Tomatoes• Lettuce• Lima beans

Fruits• Pears• Prunes• Peaches• Cantaloupes• Bananas

Dairy• Milk• Yogurt• Cottage

cheese• Ricotta cheese

Protein• Meat• Chicken• Fish• Shrimp• Beans

Grains

Dairy

(tomatoes): © Brand X Pictures/PunchStock RF; (pears): © Corbis RF; (shrimp): © Comstock Images / Jupiterimages RF


Potassium: Excess

• Typical food intakes do not lead to potassium toxicity in people with healthy kidneys

• If kidney function is poor: potassium builds up in blood, inhibits heart function & ↓ heartbeat

• No Upper Level (UL) has been set


Chloride (Cl): Functions

• Primary negatively charged ion in the extracellular fluid

• Functions:

– Component of stomach acid (HCl)

– Immune response– Nerve function


Chloride: Deficiency

• Prolonged vomiting (ex: bulimia or severe flu) can lead to acid-base disturbance due to large loss of stomach acid

• Deficiency is unlikely because dietary salt intake is so high


Chloride: Nutrient Needs

• AI for chloride is 2,300 mg/day

• Based on 40:60 ratio of sodium: chloride in salt: (1,500 mg sodium: 2,300 mg chloride)

• DV used on food labels is 5,400 mg


Food Sources of Chloride

• Fruits & Vegetables

• Chlorinated water

• Salt (NaCl)


Chloride: Excess

• Plays a role in salt in raising blood pressure

• UL is 3,600 mg/day

• Because of ↑ salt intake, average North American intake of chloride is also ↑


Phosphorus

• Functions of phosphorus:– Major intracellular negatively charged electrolyte– Required for fluid balance– Critical role in bone formation– Regulates biochemical reactions by activating or

deactivating enzymes (phosphorylation)– Found in ATP, DNA, RNA, cell membranes

(phospholipids), and lipoproteins


Phosphorus

• Recommended intake– RDA for phosphorus is 700 mg/day

• Sources of phosphorus– Widespread in many foods– High in protein foods (meat, milk, eggs)– More readily absorbed from animal sources– Phytic acid: plant storage form– Soft drinks



Phosphorus

• What happens if you consume too much phosphorus?– High blood phosphorus can occur among people

with kidney disease or when taking too many vitamin D supplements

– Causes muscle spasms, convulsions• What if you don’t consume enough

phosphorus?– Deficiencies of phosphorus are rare


Medical Disorders

• Disorders related to fluid and electrolyte imbalance include:– Dehydration– Heatstroke– Water intoxication– Hypertension– Neuromuscular disorders– Obesity



Dehydration

• Dehydration occurs when fluid loss exceeds fluid intake

• Commonly due to heavy exercise or high environmental temperatures

• Elderly and infants are at increased risk



Heatstroke

• Heatstroke occurs from failure in the body’s heat-regulating mechanisms – Hot, humid environments– Symptoms: rapid pulse, hot and dry skin, high

body temperature, loss of consciousness– Fatal during exercise in extreme heat– Stop exercising when feeling dizzy, light-headed,

disoriented, or nauseated


Water Intoxication

• Overhydration can occur but it is rare• Kidneys retain too much water, causing

overhydration and hyponatremia• Documented cases of deaths among college

students (hazing rituals)


Hypertension

• Hypertension: major chronic disease characterized by high blood pressure– Often without symptoms– Increases a person’s risk of heart disease, stroke,

kidney disease– Can reduce brain function, impair physical

mobility, and cause death– Systolic pressure over 140 mm Hg– Diastolic pressure over 90 mm Hg


Hypertension

• What causes hypertension?– Primary (or essential) hypertension:

unknown cause for 90−95% of cases – 5−10% are caused by kidney disease, sleep

apnea, and chronic alcohol abuse– Salt sensitivity: >50% adults with

hypertension


Hypertension

• Recommendations for reducing hypertension:– Losing weight – Increasing physical activity– Reducing alcohol intake– Reducing sodium intake– Eating more whole grains, fruits, vegetables, and

low-fat dairy foods– DASH diet


Hypertension

• Medications– Help in normalizing blood pressure– Should also continue to practice healthful lifestyle

changes • Hypertension: “the silent killer”

– Often no obvious symptoms of this disease – Importance of regular blood pressure check


Neuromuscular Disorders

• Electrolyte imbalances can alter nervous system and muscle function – Seizures: uncontrollable muscle spasms – Muscle cramps: involuntary, spasmodic, and

painful muscle contractions


Obesity

• Popularity of sweetened beverages (U.S.)– 21% of calories from beverages: sweetened soft

drinks, fruit juices, sweetened bottled waters, bottled teas, specialty coffee

– Appetite not curbed: extra calories from drinks are not compensated for by eating less

– Displace more nutritious beverages such as milk (source of protein, calcium, vitamin D, and other nutrients important for bone health)



Why Is Water So Important?

• Water is the most abundant substance in the body• Average healthy adult is 45–75% water depending

on– Age

• Percent of water declines with age– Composition of fat and muscle

• Muscle is ~65% water• Fat is 10–40% water

– Gender

NDD10103 PRINCIPLES OF HUMAN NUTRITIONFigure 11.1

The Composition of the Body


Why Is Water So Important?

• Water is a polar molecule– Excellent

solvent in the body

– Neutral charge

– Essential in maintaining acid-base balance


Quick Review

• Body is more than 45% water• Muscle tissue has more water than does fat

tissue– Men have more body water than women– Younger individuals have more body water than

older individuals• Water is polar• Water serves as an acid-base buffer


Functions of Water in the Body

You can survive for weeks without food,but you can survive only a few days without water


Functions of Water in the Body• Commonly known as a universal solvent• Polarity allows it to attract charged particles into solutions

and dissolve a variety of other polar substances– Important to digestion

• Helps transport dissolved nutrients and other substances throughout the body

• Blood is composed of water and red blood cells– Water allows blood to transport oxygen, nutrients, and

hormones to cells– Water helps transport waste products away from cells to be

excreted


Water Helps Regulate Body Temperature



• Lubricates joints, sensitive eye tissues, mouth, and intestinal tract

• Provides a protective cushion, bathing certain organs with fluid– During pregnancy the fetus is surrounded by

watery amniotic fluid• Provides a structural component to cells



• Water is essential for most chemical reactions in the body– During digestion water hydrolyzes the bonds

holding together• Carbohydrate molecules• Protein molecules• Fat molecules

– When smaller molecules combine through condensation water is formed


Quick Review

• Water – Universal solvent– Transports oxygen and nutrients throughout the body– Absorbs and releases heat to regulate body temperature– Acts as a lubricant– Provides a protective cushion for organs– Adds structure to cells– Participates in chemical reactions

• Hydrolysis• Condensation


Amount consumed = Amount excreted

Figure 11.4

Maintaining Water Balance• Fluid homeostatis

– Is necessary for normal reactions within the cells

– Is maintained by adaptation to changes in water intake and water loss

– Water balance


Sources of Body Water

• Largest source comes from beverages• Food is an additional source

– Except for fats, all food contains some water• Metabolic water – water generated during

metabolism

These sources contribute to an average daily intake of 2,550 ml (about 2 quarts)


Water Excretion

• Majority of fluid is excreted through the kidneys– More water that is ingested the more urine that is

produced• Excreted through intestinal fluids in the stool

– Dependant on dietary intake of plant fibers and presents of diarrhea

• Evaporated through exhalation and through the skin– Insensible water loss


Water Excretion

• Loss through sweat– Varies based on

• Environmental factors– Temperature– Humidity– Wind– Sun’s intensity– Clothing

• Amount of physical activity


Water Balance between Fluid Compartments

• Body fluid is located– Intracellular –

within the cells– Extracellular –

outside the cells


Electrolytes Participate in Fluid Balance

• Electrolytes– Minerals with electrically charged ions

• Potassium• Phosphate• Magnesium

– Help maintain water balance between compartments

• Sodium has greatest effect on fluid balance

- Calcium- Chloride- Sodium



• Osmosis– Strongest factor influencing water balance

between compartments– Water moves from a diluted concentration to a

more concentrated area– Osmolarity of a solution indicates total

concentration


Osmosis



• Sodium-potassium pump– Sodium and potassium play a key role in water

concentration inside and outside of the cells– Healthy cells

• Low concentration of sodium ions• High levels of potassium inside the cells

– Water is attracted to sodium and moves toward it– Transports three Na+ ions out of the cell in exchange

for two K+ ions • Keeps the cell from swelling and bursting


Quick Review• Water balance

– Water is consumed and is produced by the body via food, beverages, and metabolism

EQUALS– Water excreted through the kidneys, skin, lungs, and feces

• Body water is contained in either– Intracellular fluid compartments – majority of body water– Extracellular fluid compartments

• Interstitial• Intravascular


Quick Review

• Osmosis is the process of water moving from an area of higher concentration to an area of lower concentration across a cell membrane

• Sodium-potassium pump helps maintain electrolyte and fluid balance inside and outside of cells


How Do Water and Sodium Affect Blood Pressure?

• If the body retains too much fluid, blood volume increases and blood pressure will likely rise

• Kidneys help regulate blood volume and electrolyte balance through tightly controlled hormone signals


How Do Water and Sodium Affect Blood Pressure?

• Three hormones and one enzyme work together to orchestrate the retention and excretion of water and electrolytes base on blood volume

• Hormones– Antidiuretic hormone (ADH), also called vasopressin– Angiotensin– Aldosterone

• Enzyme– Renin


ADH

• Blood volume drops– Hypothalamus detects decrease in blood pressure and

increase in concentration of salts– Thirst mechanism and fluid intake are stimulated– Hypothalamus stimulates pituitary glands to release

ADH– ADH stimulates the kidneys to reabsorb water and

decrease urine output– Blood volume increase and osmolality returns to

normal


Renin

• Blood pressure falls and sodium concentration is reduced– Renin is secreted by the kidneys

• Enzyme splits off a protein called angiotensin I from the protein angiotensinogen found in the blood

• In the lungs angiotensin I is converted to angiotensin II– Angiotensin II is a powerful vasoconstrictor


Aldosterone• Renin-angiotensin system adapts to changes in dietary

sodium intake– Consume too little sodium– Osmolality drops in extracellular fluid (ECF)– Fluid shifts from the blood to the interstitial fluid– Blood volume and blood pressure decrease– Angiotenson II triggers the adrenal glands to release

aldosterone• Aldosterone

– Signals kidneys to retain more sodium– Indirectly leads to water retention


Blood Volume Regulates Blood Pressure


Quick Review

• Changes in blood volume and osmolality– Body takes actions to maintain homeostasis and return

blood pressure to normal– Antidiuretic hormone (ADH) and aldosterone direct the

kidneys to reabsorb water and sodium– Renin increases sodium retention– Angiotensin II is a vasoconstrictor

• These control mechanisms adjust to the changes in dietary sodium and fluid intake to prevent hypertension


How Much Water? What Are the Best Sources?

• Water needs depend on– Physical activity– Environmental factors– Diet

• Recommendations– 80% intake from beverages and 20% from food– Adult women: approximately 9 cups of fluid per day– Adult men: approximately 13 cups of fluid per day– A well-balanced 2,200 kilocalorie diet that includes

beverages at all meals and snacks will provide about 12 cups of water


Daily Beverage Recommendations


How Much Water? What Are the Best Sources?

• Drinking bottled or tap water, milk, and juices throughout the day can help meet the body’s needs

• Most foods can also contribute to daily water need– Fruits and vegetables can be 70% or more

water by weight– Dry grain products provide some water


Quick Review

• Daily water needs vary according to– Physical activity levels, environment, diet

• Adult women should consume about 12 cups per day– 9 cups from beverages– 3 cups from food

• Adult males should consume about 16 cups per day– 13 cups from beverages– 3 cups from foods

• Active individuals will need more water to avoid dehydration


Do Diuretics Like Caffeine and Alcohol Affect Water Balance?

• Alcoholic drinks, regular coffee, and tea contribute to total water intake

• Alcohol and caffeine are considered diuretics– Contribute to water loss– Overconsumption can upset fluid balance


Caffeine

• Mild diuretic that blocks the action of ADH in the kidneys

• Research unable to confirm that this mild diuretic actually results in dehydration

• Caffeine doesn’t cause a significant loss of body water over the course of the day compared to noncaffeinated beverages

• Tolerance to diuretic effects develops over time


Alcohol

• Inhibits ADH• Can induce urination as quickly as 20 minutes after

consumption• Can be dehydrating• Effects electrolytes, especially potassium• Older drinkers are less effected than younger drinkers• To prevent dehydration

– Reduce alcohol consumption– Drink water after consuming alcohol


Diuretic Medications Can Help Treat Hypertension

• First line of treatment for hypertension– Often pharmaceutical diuretics

• Promote diuresis by inhibiting the reabsorption of sodium

• Increased sodium excretion increases fluid excretion• Reduces blood volume and lowers blood pressure

• Some diuretics increase potassium loss and the risk of hypokalemia


Quick Review

• Moderate caffeine intake does not affect fluid balance

• Alcohol reduces the effects of ADH and can cause dehydration

• Pharmaceutical diuretics are prescribed to reduce hypertension

• Pharmaceutical diuretics may cause electrolyte imbalances


Effects of Too Much Water

• Water intoxication– Rare in healthy individuals who consume a balanced diet– Drinking fluid too fast without adequate sodium

replacement depletes sodium and increases the rate of urine production

• Results in hyponatremia– Can cause swelling in the brain

• Fatique• Confusion• Disorientation


Effects of Too Little Water

• Dehydration can result from– Not drinking enough water– Losing excessive amounts of water due to diarrhea,

vomiting, high fever, or use of diuretics– As little as a 2% loss of body water can trigger

• Loss of short-term and long-term memory• Lower attention span and cognition• Reduced ability to maintain core temperature• Increase risk of urinary tract infections and fatigue

• Consequences of dehydration can be severe for children, elderly, and athletes



Thirst Mechanism Signals Dehydration• Thirst is often the first

sign of dehydration• Urge to drink is

important in preventing dehydration and restoring water balance

• Less circulating blood can lead to Reduced blood pressure Hypotension if severe

enough


Thirst Mechanism Signals Dehydration

• Hypovolemia and hypotension can– Reduce cardiac output– Impair digestion– May cause fainting and blacking out

• When dehydrated– Water is depleted from extracellular fluid and

intracellular fluid


Monitor Water Intake to Avoid Overhydration and Dehydration

• Measure body weight before and after long bouts of vigorous physical activity or labor and note changes– If weighs less after an activity the change is due

to loss of body water– If weight gain is noted overhydration is likely

• Consume less fluid before next activity


Monitor Water Intake to Avoid Overhydration and Dehydration

• Urine color can be used to assess hydration– Individuals who are dehydrated produce less

urine due to the release of ADH– With dehydration urine is more concentrated and

darker in color– Darker urine indicates possible need to increase

fluid intake


Putting It All Together• Water is

– A universal solvent– The main component of fluids in which all reactions

involving the energy-producing nutrients take place in the body

• Vitamins and minerals aid in these chemical reactions

• Nutrients work in conjunction with water to meet metabolic needs

• Consuming a wide variety of foods from all food groups, with an emphasis on maintaining sufficient fluid intakes, is the best diet prescription to meet the body’s needs for carbohydrate, proteins, fat, vitamins, minerals, and water


Thank you!

Health & Medicine

Lecture 9 nutrients involved in fluid and electrolyte balance