The most common fat-containing foods are butter, cream, eggs, fatty meats, margarine, oily fish, and vegetable oils. Other fats become an essential part of cells. They are available as fuel for energy at any time. The stored fats surround and protect internal organs, such as the kidneys, and act as insulation that prevents heat loss. Fats also provide an environment in which vitamins A, D, E, and K can dissolve.
Some fat is stored in the liver.
Saturated and unsaturated fats differ chemically in the way their carbon and hydrogen atoms are arranged. Basically, unsaturated fats can absorb hydrogen, whereas saturated fats can not. Fish oil may lower blood levels of certain harmful fats. Research suggests that large amounts of saturated fats in the diet may be associated with increased plasma cholesterol and atherosclerosis. Surveys have shown that countries with high living standards, such as the United States, have a high incidence of atherosclerosis.