The term "fat" includes fats from meat, fish, poultry, and dairy products as well as vegetable oils and the nuts, seeds, and grains from which they have been extracted. There are two basic kinds of fats—saturated, occurring mostly in animal foods (although some vegetable fats such as the kind that coconut contains fall into this category too), and unsaturated, in the form of vegetable oils such as safflower, corn, and sunflower, and in seeds and nuts. Fish tends to contain more unsaturated than saturated fats, meat more saturated than unsaturated.
Whether saturated or unsaturated, all the fats you eat rapidly form a film around blood cells and platelets, creating a kind of sludge which causes them to stick together. This clumping significantly interferes with circulation by clogging blood vessels and even temporarily closing down small capillaries. As a result, your cells do not receive all the oxygen and nutrients they need to function efficiently. They only run at about 80 percent capacity. This interferes with cell metabolism as well as with the efficient elimination of cellular and tissue wastes.
The chemical structure of an unsaturated fatty acid differs from its saturated brother in that at least two of the carbon atoms in its formula are free. This means that they have no hydrogen atoms attached to them, as the molecule of a saturated fatty acid does. It was long thought that while saturated fats were bad for you, unsaturated fats were good. For unsaturated fats have been shown to reduce cholesterol levels in the blood, and therefore were believed to be helpful in preventing arteriosclerosis and coronary heart disease. That is the reason we have been encouraged in the last thirty years or so to include plenty of polyunsaturates in our diet by switching from butter to margarine and vegetable oils. The catch is that although unsaturates do this, like all fats they still raise triglyceride levels (another factor linked with coronary heart disease) and they also create the same clumping as the saturated fats do, which leads to tissue anoxia.
Women have also lately been encouraged by poorly informed writers to include lots of polyunsaturates in their diet for their beauty's sake. Unsaturated fatty acids are an important constituent of skin and muscle tissue and so it was thought, quite wrongly, that we need more of them. For what we have not been told is that the chemical structure of unsaturated fats with their free carbon atoms makes them extremely unstable compounds, and that when an unsaturated fat is exposed even to the smallest trace of a catalytic agent it begins a process of autooxidation which results in the fat molecule's breaking down to produce what are known as free radicals.
Free radicals are highly reactive particles which, if left unchecked in the presence of oxygen molecules, will form toxic peroxides. These peroxides can damage and destroy cells. They have also been implicated as a primary cause of the aging process itself. When a cell, or the genetic material of a cell, is destroyed by free radicals, the result is something known as a lipofuscin pigment granule—often referred to by biochemists as a "clinker." With age, ever more cells are damaged or destroyed as tissue degenerates, leading to increase in the number of these pigment granules. This is something you want to avoid in every way you can if you don't want to look and be old before your time.
To some extent, the presence of sufficient amounts of an antioxidant such as vitamin E in the system may prevent this from happening, because it minimizes the damage done by free radical chain reactions by breaking the chain. Vitamin E, like other antioxidants, helps block the oxidation that turns fatty acids into harmful peroxides. The more unsaturated fatty acids in your diet, the greater will be your need for the vitamin.
An interesting dietary survey that was done at the University of California at Irvine looked at over 1,000 patients and examined the degree of wrinkling and crow's-feet, frown lines, and other indications of skin degeneration such as damage to the collagen and elastin fibers and the irregular pigmentation characteristic of old skin. The subjects ranged in age from seventeen to eighty-one and 76 percent of them were women. Cadvan Griffiths, M.D., the professor of surgery who carried out the study, discovered that there is an undeniable link between marked clinical signs of aging and the intake of unsaturated fats in one's diet. Those who regularly and frequently included polyunsaturated fats and oils in their diet had marked signs of premature aging. Some looked as much as twenty years older than they were. Very few of those who had made no special effort to eat more polyunsaturates showed any clinical signs of premature aging. Evidence is also accumulating that links free radical reactions to the etiology of cancer, senility, atherosclerosis and hypertension—all of them disorders generally associated with aging. This is all the more reason to limit the amount of every kind of fat you eat to no more than you actually need.