Lipid Functions

It can be argued that lipids may be the most important of all dietary constituents since they are required in the highest levels, aside from water, in every living cell. Lipids are a concentrated source of energy providing more than double the amount on a per-weight basis than that contained in either carbohydrates or proteins. They help maintain body temperature through both their insulating effects and the heat generated from their oxidation. They also physically protect and insulate nerves and cushion other tissues and organs.

But the effects of lipids are far more profound and far-reaching than these rather simple and well known functions. They are not just fuel to be burned and padding for tissue; they can also be dynamic, complex metabolic biochemicals that enter into an extremely wide range of important physiologic pathways. They are part of glandular secretions, they help muscles recover, they are necessary for growth, tissue repair, and reproduction. They help create culinary interest, provide satiety, carry fat soluble vitamins, are a part of hormones, and they can affect blood clotting, inflammation, respiration, susceptibility to and recovery from disease. (Fig. 1)

Clinically, fatty acids are becoming more and more important. Their deficiency, absence, alteration, or imbalance is now related to cardiovascular disease, arthritis, cancer, headaches, hypertension, autoimmune disease, muscular sclerosis, psoriasis, lupus, diabetes, and various other wide-ranging free radical and fatty degenerative diseases.1-5 Lipids serve as important substrates and modulators throughout the body and thus can potentially affect virtually any life process. The effects of lipid malnutrition will thus very likely be increasingly linked to more and more disease conditions as biochemical and physiological mechanisms become increasingly elucidated.

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A more complete understanding of these dynamic functions and of proper lipid nutrition is aided by a grasp of lipid biochemistry. Although the following chapter will challenge readers with little science background, the effort to understand as much as is possible will reap many rewards in understanding subsequent topics. Comprehending every detail of biochemistry, however, is not essential to grasping the practical applications that will be developed later in the book.

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