Updated: Feb 7
LET'S TALK ABOUT FAT
Fats from animal and vegetable sources provide a concentrated source of energy in the diet; they also provide the building blocks for cell membranes and a variety of hormones and hormone like substances.
Fats as a part of a meal slow down nutrient absorption so that we can go longer without feeling hungry. In addition, they act as carriers for important fat-soluble vitamins A, D, E and K.
Dietary fats are needed for the conversation of carotene to Vitamin A, for mineral absorption and for a host of other processes.
We live in a world where fats have been demonised, particularly saturated fats from animal sources. Fats from animal sources also contain cholesterol, which is also presented as the twin villain of the civilised diet.
The theory is that there is a direct correlation between the amount of saturated fat and cholesterol in the diet and the incidence of coronary heart disease.
Most people would be surprised to learn that there is, very little evidence to support the contention that a diet low In cholesterol and saturated fat actually reduces death from heart disease or in any way increases one’s life span.
Fats or lipids are a class of organic substances that are not soluble in water. In simple terms, fatty acids are chains of carbon atoms with hydrogen atoms filling the available bonds.
Most fat in our bodies and in the food we eat is in the form of triglycerides, that is, 3 fatty-acid chains attached to a glycerol molecule.
Elevated triglycerides in the blood have been positively linked to proneness to heart disease, but these triglycerides do not come directly from dietary fats; they are made in the liver from excess sugars that have not been used for energy.
The source of these excess sugars in food containing carbohydrates, particularly refined sugars and white flour.
Saturated a fatty acid is saturated when all available carbon bonds are occupied by a hydrogen atom. They are highly stable, because all the carbon-atom linkages are filled, or saturated with hydrogen. This means that they do not normally go rancid, even when heated for cooking purposes. They are straight in form and hence pack together easily, so that they form a solid or semisolid fat at room temperature. Saturated fatty acids are found mostly in animal fats and tropical oils, and our body also makes them from carbohydrates.
Polyunsaturated They have 2 or more pairs of double bonds and therefore lack 4 of more hydrogen atoms. The 2 polyunsaturated fatty acids found most frequently in our foods are double unsaturated linoleic acid, with 2 double bonds, also called omega 6; and triple unsaturated linolenic acid, with 3 double bonds, also called omega 3. Your body cannot make these fatty acids hence they are called essential. We must obtain our essential fatty acids from foods we eat. Polyunsaturated fatty acids have kinks or turns at the position of the double bond hence do not pack together tightly. They remain liquid, even when refrigerated. The unpaired electrons at the double bonds make these oils highly reactive. They go rancid easily, particularly omega 3, and must be treated with care. Polyunsaturated oils should never be heated or used for cooking.
Monounsaturated They have one double bond in the form of 2 carbon atoms double-bonded to each other and therefore lack 2 hydrogen atoms. Your body makes monounsaturated fatty acids from saturated fatty acids and uses them in many ways. Monounsaturated fats have a kink or bend at the position of the double bond so that they do not pack together as easily as saturated fats and therefore tend to be liquid at room temperature. Like saturated fats, however, they are relatively stable. They do not go rancid easily and hence can be used in cooking. The monounsaturated fatty acid most commonly found in our food is oleic acid, the main component of olive oil as well as the oils from almonds, pecans, cashews; peanuts and avocados.
All fats and oils, whether of vegetable or animal origin, are some combination of saturated fatty acids, monounsaturated fatty acids and polyunsaturated linoleic acid and linolenic acid. In general, animal fats such as butter, and lard contain about 40-60% saturated fat and are solid at room temperature. Vegetable oils from northern climates contain a preponderance of polyunsaturated fats and are liquid at room temperature. But vegetable oils from tropics are highly saturated. Coconut oil, for example, is 92% saturated. These fats are liquid in the tropics but hard as butter in northern climates.
Fatty acids are not just classified fatty acids only according to their degree of saturation but also by their length.
Short-chain fatty acids have 4 to 6 carbon atoms. These fats are always saturated. 4 carbon butyric acid is found mostly In butterfat from cows and 6 carbon capric acid is found mostly In butterfat from goats.
These fatty acids have antimicrobial properties, that is, they protect us from viruses, yeasts and pathogenic bacteria in the gut. They do not need to be acted on by bile salts but are directly absorbed for quick energy. For this reason they are less likely to cause weight gain than olive oil or commercial vegetable oils. Short-chain fatty acids also contribute to the health of the immune system.
Medium-chain fatty acids have 8 to 12 carbon atoms and are found mostly In butterfat and tropical oils. Like short-chain fatty acids l, these fats have antimicrobial properties, are absorbed directly for quick energy, and contribute to the health of the immune system.
Long-chain fatty acids have from 14 to 18 carbon atoms and can be either saturated, monounsaturated or polyunsaturated. Stearic acid is an 18-carbon saturated fatty acid found chiefly in beef . Oleic acid is an 18-carbon monounsaturated fat which is the chief component of olive oil. Another monounsaturated fatty acid is the 16-carbon palmitoleic acid which has strong antimicrobial properties. It is almost found exclusively in animal fats. The 2 essential fatty acids are also long chain, each 18 carbons in length. Another important long-chain fatty acid is gamma-linolenic acid, which has 18 carbons and 3 double bonds. It is found in primrose oil. A healthy body can make GLA out of omega 6 linoleic acid. GLA is used in the production of substances called prostaglandins, localised tissue hormones that regulate many processes at the cellular level.
Very-long-chain fatty acids have 20 to 24 carbon atoms. They tend to be highly unsaturated, with 4, 5 or 6 double bonds. Some people can make fatty acids from EFA’s, but others, particularly those whose ancestors ate a lot of fish lack enzymes to produce them. The most important dihomo-gamma-linolenic acid (DGLA)with 20 carbons and 3 double bonds, arachidonic acid (AA) with 20 carbons and 4 double bonds, eicosapentaenoic acid (EPA) with 20 carbons abs 5 double bonds, and docosahexaenoic acid with (DHA) 22 carbons and 6 double bonds. All of these expect DHA are used in the production of prostaglandins. In addition, AA and DHA play important roles in the function of the nervous system.
Dietary gurus tell us that polyunsaturated oils are good for us and that saturated fats cause cancer and heart disease. Such misinformation about the relative virtues of saturated fats versus polyunsaturated oils has caused profound changes in our eating habits.