Dietary fats: Know which types to choose

When choosing fats, pick unsaturated fat over saturated or trans fat. Here's how to know the difference.

By Mayo Clinic Staff

Most foods contain several different kinds of fat, and some are better for your health than others. You don't need to completely eliminate all fat from your diet. In fact, some fats actually help promote good health. But it's wise to choose the healthier types of dietary fat and then enjoy them — in moderation.

The facts about fat

There are numerous types of fat. Your body makes its own fat from taking in excess calories. Some fats are found in foods from plants and animals and are known as dietary fat. Dietary fat is a macronutrient that provides energy for your body. Fat is essential to your health because it supports a number of your body's functions. Some vitamins, for instance, must have fat to dissolve and nourish your body.

But there is a dark side to fat. Fat is high in calories and small amounts can add up quickly. If you eat more calories than you need, you will gain weight. Excess weight is linked to poor health.

The concern with some types of dietary fat (and their cousin cholesterol) is that they are thought to play a role in cardiovascular disease and type 2 diabetes. Dietary fat also may have a role in other diseases, including obesity and cancer.

Research about the possible harms and benefits of dietary fat is always evolving. And a growing body of research suggests that when it comes to dietary fat, you should focus on eating healthy fats and avoiding unhealthy fats. Simply stated, fat is made up of varying amounts of fatty acids. It's the type and amount of fatty acid found in food that determines the effect of the fat on your health.

Harmful dietary fat

There are two main types of potentially harmful dietary fat — fat that is mostly saturated and fat that contains trans fat:

Saturated fat. This is a type of fat that comes mainly from animal sources of food, such as red meat, poultry and full-fat dairy products. Saturated fat raises total blood cholesterol levels and low-density lipoprotein (LDL) cholesterol levels, which can increase your risk of cardiovascular disease. Saturated fat may also increase your risk of type 2 diabetes.

Trans fat. This is a type of fat that occurs naturally in some foods in small amounts. But most trans fats are made from oils through a food processing method called partial hydrogenation. By partially hydrogenating oils, they become easier to cook with and less likely to spoil than do naturally occurring oils. Research studies show that these partially hydrogenated trans fats can increase unhealthy LDL cholesterol and lower healthy high-density lipoprotein (HDL) cholesterol. This can increase your risk of cardiovascular disease.

Most fats that have a high percentage of saturated fat or that contain trans fat are solid at room temperature. Because of this, they're typically referred to as solid fats. They include beef fat, pork fat, butter, shortening and stick margarine.

Healthier dietary fat

The types of potentially helpful dietary fat are mostly unsaturated:

Monounsaturated fat. This is a type of fat found in a variety of foods and oils. Studies show that eating foods rich in monounsaturated fats (MUFAs) improves blood cholesterol levels, which can decrease your risk of heart disease. Research also shows that MUFAs may benefit insulin levels and blood sugar control, which can be especially helpful if you have type 2 diabetes.

Polyunsaturated fat. This is a type of fat found mostly in plant-based foods and oils. Evidence shows that eating foods rich in polyunsaturated fats (PUFAs) improves blood cholesterol levels, which can decrease your risk of heart disease. PUFAs may also help decrease the risk of type 2 diabetes.

Omega-3 fatty acids. One type of polyunsaturated fat is made up of mainly omega-3 fatty acids and may be especially beneficial to your heart. Omega-3, found in some types of fatty fish, appears to decrease the risk of coronary artery disease. It may also protect against irregular heartbeats and help lower blood pressure levels. There are plant sources of omega-3 fatty acids. However, the body doesn't convert it and use it as well as omega-3 from fish.

Foods made up mostly of monounsaturated and polyunsaturated fats are liquid at room temperature, such as olive oil, safflower oil, peanut oil and corn oil. Fish high in omega-3 fatty acids include salmon, tuna, trout, mackerel, sardines and herring. Plant sources of omega-3 fatty acids include flaxseed (ground), oils (canola, flaxseed, soybean), and nuts and other seeds (walnuts, butternuts and sunflower).

Radium

Radium has been used in medicine as a source of radiation to treat certain types of malignant growths such as cancer. Radiation given off by radium either destroys living cells or injures them severely. This property makes radium extremely dangerous to handle, but it also accounts for radium's usefulness in the treatment of cancer. If ingested, radium will become deposited in the bones and, in time, will cause damage to body tissues. Radium emits alpha particles, beta particles, and gamma rays. Radium has a half-life of 1,620 years (meaning that one ounce of radium is reduced by radioactive decay to one-half an ounce in 1,620 years). Radium decays to form radon, a radioactive gas. Radon decays to form another radioactive substance, which produces still another radioactive substance, and so on until finally lead is produced. Radium is present in tiny amounts in seawater and in most of the earth's rocks. Its chief sources

are pitchblende and other ores of its mother element, uranium. The principal sources have been mines in the Czech Republic, Canada, and Zaire. The first steps in extracting radium from uranium ore are to crush the ore and dissolve it with sulfuric acid. Radium was discovered by Marie and Pierre Curie in Paris in 1898. Earlier that year they had discovered a new element, polonium, in pitchblende. Working with an assistant, G. Bmont, they then found that there was another, more radioactive, element in pitchblende—radium. They isolated a radium salt in December, 1898. After years of arduous and dangerous labor, during which they processed tons of pitchblende, the Curies isolated 1/10 of a gram of radium chloride. Pure radium was not isolated until 1910, when Marie Curie obtained it from molten radium chloride.

The danger of radium radiation was not understood at first. In 1901, however, Henri Becquerel suffered a burn from carrying a piece of radium salt in his watch pocket. Pierre Curie then deliberately burned himself to learn the effects of radium on the body. His report immediately suggested to doctors that radium, by destroying cells, might be useful in the treatment of cancer.

Rusting

For iron to become iron oxide, three things are required: iron, water and oxygen. Here's what happens when the three get together:

When a drop of water hits an iron object, two things begin to happen almost immediately. First, the water, a good electrolyte, combines with carbon dioxide in the air to form a weak carbonic acid, an even better electrolyte. As the acid is formed and the iron dissolved, some of the water will begin to break down into its component pieces -- hydrogen and oxygen. The free oxygen and dissolved iron bond into iron oxide, in the process freeing electrons. The electrons liberated from the anode portion of the iron flow to the cathode, which may be a piece of a metal less electrically reactive than iron, or another point on the piece of iron itself.

The chemical compounds found in liquids like acid rain, seawater and the salt-loaded spray from snow-belt roads make them better electrolytes than pure water, allowing their presence to speed the process of rusting on iron and other forms of corrosion on other metals.

The two conditions necessary for the rusting of iron to occur are:

1. Presence of moisture, and2. Presence of oxygen.

The following factors further catalyst the process of rusting.

1. Presence of carbon dioxide2. Presence of acids.3. Presence of impurities in their on.

Due to rusting iron object loses its strength.

Prevention of RustingThere are several ways of preventing rusting of iron. Some of these are discussed below:1. Barrier protection:

In this method, a barrier film is introduced between iron and atmospheric oxygen and moisture. Barrier protection can be achieved by one of the following ways:

1. By painting the surface2. By coating the surface with a thin film of oil or grease.3. By electroplating iron with some non-corrosive metal such as nickel,

chromium, copper, etc.2. Sacrificial protection:

In this method, surface of iron is covered with layer of more active metal like zinc. This active metal loses electrons (undergoes oxidation) in preference to iron and hence, prevents the rusting of iron.

Zinc metal is generally used for protecting iron and the process is called galvanization. Galvanized iron sheets maintain their shine due to the formation of a thin protective layer of basic zinc carbonate, ZnCO3, Zn (OH) 2 due to the reaction between zinc, oxygen, CO2 and moisture in air.

Zinc, magnesium and aluminum powder dissolved in paints can also be applied as protective layers. The well-known aluminum paint contains aluminum powder suspended in varnish.

3. Use of anti-rust solutions:

The alkaline phosphate and alkaline chromate solutions act as anti-rust solutions. When iron articles are dipped into a boiling and strongly alkaline solution of sodium phosphate, a protective insoluble film of iron phosphate is formed on them. This film protects the article from rusting.

Does iron increase in weight when it rusts? | Improve this answer   | More answers ►  

The answer is yes and no. Let’s consider the yes part first. What happens when iron rusts is that the outside of it, which is exposed to the air, corrodes or oxidizes. A certain amount of oxygen of the air is added to the iron. This

oxygen, like everything else, has weight, and its weight (actually relative atomic mass of 15.9994) must be added to that of the iron itself when the iron is rusty. Therefore, the answer to the question must be yes. Iron increases in weight. But as everyone knows, the rust, or oxide of iron, is friable; a Latin word which means that it crumbles easily.

Now the answer which is clearly no. The rust will crumble away under the influence of water or wind or anything else rubbing against the iron. Therefore, the iron object will lose not only the oxygen that it has taken into itself, but also the part of the iron which has combined with oxygen. So the material made of iron, when it rusts, loses weight. The whole piece crumbles into red dust eventually. This is very serious, of course, for it means that the object loses its strength. And if an iron and steel bridge were allowed to decay in this fashion, it would soon break. That is one reason why such a bridge is painted to protect the iron from the air.

Every year I have lots of people ask me this question (especially younger visitors doing certain science courses and exams across the world) and so I have decided to make this a special one-off web page on this subject!

The claims that have become popular on a number of examination courses around the world are that:

1. Wasp sting venom is alkaline and so its effects can be neutralised with vinegar or acid and this neutralisationthen reduces the pain.

2. Bee sting venom is acidic and so its effects can be neutralised with bicarbonate of soda or alkali and this reaction reduces the pain.

Are either of these statements true?

The facts are that:

Bee venom contains formic acid (also known as methanoic acid) but this is not the single active ingredient that causes the pain from a bee sting

Wasp stings are alkali but once again the venom has so many active ingredients that it is very unlikely that it is the alkali alone that is the single active ingredient that causes the pain

Neutralising a sting with either vinegar or bicarbonate of soda is unlikely to be effective or even practically possible because:

1) The venom from wasps and bees is injected under the skin and after a few minutes spreads deep into the tissues. Sloshing unknown strength vinegar or bicarbonate of soda onto the skin surface is unlikely to even get near the venom so no “neutralisation” is likely to take place anyway.

2) A wasp or bee sting is between 5 and 50 micrograms of fluid – this is a tiny amount of fluid – a little pinhead or the size of this full stop . – and it is hard to believe how pouring comparatively huge volumes of unknown strength vinegar or rubbing lumps of bicarbonate of soda near the venom of unknown pH is going to produce a perfectly neutral pH which neutralises the sting and stops it hurting.

So, I confidently state that vinegar and bicarbonate of soda (or at least their acidity or alkalinity) have no real physical effect on how much a sting hurts or continues hurting.

I would also add that

rubbing a wound distracts the mind from the immediate pain and rubbing a wound with anything safe promotes the release of endorphins which

may reduce the pain,

if you believe something is going to work, then it often will because the mind can play curious tricks!

There are plenty of very subjective but genuine and honest claims for the following treatments:

applying meat tenderizer, applying toothpaste,

applying tobacco,

applying papain (latex from the papaya tree)

applying mashed up root of pineapple

applying chilli paste

applying Mum roll on deoderant,

applying mint leaves

applying four types of grass

applying clay paste, and

applying a copper coin

squeezing the sting with a clothes peg for 20 minutes

applying a paste of green clay

applying hot water to coagulate the venom

applying lavendar oil

applying crushed bracken fern

applying Sudocrem to sting site

applying a slice of raw onion

applying aluminium sulphate

using WD40

applying ice and cold water

apply hot or near boiling water

applying plantain leaves mixed with saliva as a poultice

applying charcoal and flaxseed jelly

Strength of Acids

The ability of an acid to release hydrogen ions is specified by its strength. A strong acid (for example, sulfuric or hydrochloric acid) dissociates (breaks up) completely, or nearly completely, into positive and negative ions in a dilute (nonconcentrated) water solution. Only a small percentage of a weak acid (for example, acetic acid), on the other hand, forms ions in solution, the major portion of the acid remaining in the form of molecules. As a general rule, inorganic acids are stronger than organic acids. The formation of positive and negative ions is the reason that an acid in a water solution will conduct electricity.

The strength of an acid is denoted by its pH. The pH value of a dilute solution is given approximately by the following expression:

pH = log 1/[H+]

In this expression [H+] is a number whose value is determined by the quantity of hydrogen ions per unit volume. The pH of a solution can range from 0 to 14. Pure water, which is neutral (that is, neither an acid nor a base), has a pH of 7. Substances with pH

values of less than 7 are acids, and substances with pH values of more than 7 are bases. Strong acids have pH values near 0, while strong bases have pH values near 14.

Properties of Acids

At ordinary temperatures, most pure acids are solids. Many, however, are liquids, and a few are gases. Some acids, such as prussic acid (hydrogen cyanide), are deadly poison.

When acids are dissolved in water in sufficiently high concentration they typically have the following properties:

1. They have a sour taste. (The term acid is derived from acidus, the Latin word for sour.)

2. They are corrosive.

3. They will turn blue litmus paper red.

4. They will dissolve many metals (for example, iron, tin, and zinc) and at the same time release hydrogen gas.

5. They will conduct an electric current, with the simultaneous liberation of hydrogen gas.

Acids will react with substances called bases (for example, sodium hydroxide) to form salts (such as sodium chloride, or table salt). A base is a substance that is capable of accepting hydrogen from another substance; thus it can be considered the opposite of an acid.

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Structure of Acids

The simplest type of acid has a molecule consisting of one atom of hydrogen and one atom of a nonmetallic element. A molecule of hydrochloric acid, for example, contains one atom of hydrogen and one atom of chlorine. Hydrochloric acid can be obtained by dissolving hydrogen chloride, a gas, in water. Both fndrochloric acid and hydrogen chloride have the chemical formula HCl, H being the symbol for hydrogen and Cl the symbol for chlorine.

Sodium chloride, one of the many chemical compounds classified as a salt, can be formed by combining metallic sodium (Na) with hydrochloric acid. The sodium replaces the hydrogen, as indicated by the chemical equation for this reaction:

2 Na + 2 HCl>2 NaCl + H2