Fats: Essential for Life
While it is true that fats have taken a beating in the media and are frowned upon for their negative biological impact, they are absolutely essential for life. I want to strongly reiterate here that it is not so much the quantity of fat we consume as what type of fats we eat.
Lipids are considered a group of fats and fat-like compounds that are insoluble in water. Technically speaking, this category of macronutrients includes fats, fatty acids, oils, waxes, sterols, and esters of fatty acids. Much like carbohydrates, lipids are chemically comprised of carbon, hydrogen and oxygen atoms. They serve as a source of energy which is either 1) converted to other essential tissue components, 2) burned off, or 3) stored as fat in adipose tissue.
Keep in mind that the macronutrient category of fats does not refer to body fat which ideally accounts for around 10 percent of the body weight of a normal adult. The more we learn about fats, the more convinced we all should be that bad dietary fats are really bad and good ones are absolutely vital and should be consumed in the proper proportion. Dietary lipids in the form of olive oils, flaxseed oils, and canola oil are an excellent source of nutrition and can actually discourage cardiovascular disease rather than contribute to it. Lipids provide us with a high-energy food source, facilitate digestive processes, help to metabolize other nutrients and contribute to the absorption and transport of the fat-soluble vitamins (A, D, E, K). In addition, they comprise the sheathes that protect our nerves and help to make up fat stores to protect our vital organs.
If lipids are missing from our diets, the body will synthesize some fatty acids from other macronutrients; however, linoleic acid is considered an essential fatty acid which means that it cannot be synthesized and can only be obtained from food or supplement sources. For example, flaxseed oil is a very good source of this essential fatty acid. We are just beginning to understand the profound health implications of this acid which serves as a precursor to a series of hormone-like substances called prostaglandins. It would be wise to mention here that as Americans, the majority of fats we eat are saturated and hydrogenated varieties. Many of these artificially manipulated fats (such as we see in vegetable margarines) produce dangerous fat compounds and are completely lacking in essential fatty acids. Because we do not consume fish routinely and typically do not use olive, flaxseed or evening primrose oils in our diets, supplementation is very much warranted. Deficiencies in these essential fatty acids have been linked with all kinds of autoimmune diseases, including multiple sclerosis and lupus.
Triglycerides are considered the major form of fat and make up the majority of fat found in foods and in the body. What we need to know about triglycerides is that the length and degree of their saturation as chemical compounds determines the way they behave in the body. Fatty acids are chemically comprised of carbon atoms. If each carbon atom is connected to each of its hydrogen neighbors, it is called saturated. If two adjacent carbon atoms are linked in a double bond and could bind to additional hydrogens, the fat is called monosaturated. If more than one locality on a carbon chain is able to accept additional hydrogen atoms, the fat is called polyunsaturated. Linoleic acid is a polyunsaturated fatty acid and oleic acid is an example of a monounsaturated fatty acid.
An easy way to recognize some unsaturated fats is that they are usually more liquid at room temperature than a saturated fat. For example, sunflower oil, high in polyunsaturated fatty acids, is liquid at room temperature, while lard or butter, high in saturated fats, is solid.