Cholesterol Symptoms and Treatment
Cholesterol is widely distributed in animal tissues, but is found in highest concentrations in nerve and brain tissue. Medical interest in cholesterol is based both on its role in normal body physiology and on its relationship to disease.
Although the exact role of cholesterol in the normal body is unclear, there are several indications that it must have considerable importance. Its high concentration in all nerve tissues suggests that it plays a vital role in nerve conduction.
Cholesterol is similar in chemical structure to the sex and adrenal cortical hormones, which are derived from cholesterol by the body. Cholesterol is also a precursor of bile salts. The liver normally synthesizes large quantities of cholesterol.
Cholesterol in Disease
Cholesterol is of considerable importance in a number of diseases. Gallbladder stones are composed mainly of cholesterol; in fact, gallstones may be more than 90% cholesterol. However, the actual cause and process of formation of gallstones is not known. In the condition known as xanthomatosis, there are abnormal cholesterol deposits in various tissues, including the skin.
Deposits of cholesterol are found in the lining of arteries in a group of diseases of the blood vessels and heart. These deposits, which may be quite thick, roughen the interior of the arteries and make clot formation more likely . Sometimes the deposits are so thick that the blood flow past them is decreased to such an extent that the tissues supplied by the vessel do not receive an adequate amount of blood. With greater blockage of the vessel, parts of the organs deprived of blood may die (infarct). Sometimes the deposition of cholesterol so greatly reduces the elasticity of the arterial wall that the wall splits and bleeding occurs.
Diseases related to cholesterol deposition in the arteries include arteriosclerosis, angina pectoris, myocardial infarction (coronary thrombosis, heart attack), cerebral vascular disease, stroke, and dissecting aortic aneurysm.
Cholesterol in the Diet
It is thought that a reduction in the dietary intake of cholesterol might be helpful in preventing and controlling diseases of the blood vessels. Although the liver produces far more cholesterol (endogenous cholesterol) than is usually eaten in food (exogenous cholesterol), it appears that the dietary cholesterol is more likely to be deposited in the arteries than the endogenous cholesterol. Accordingly, some doctors now advise limitation in the intake of high-cholesterol foods such as brains, egg yolk, liver, kidney, sweetbreads, butter, cream, and some cheeses.
Importance of Unsaturated Fats in the Diet.
It has been found that the kind and amount of fat in the diet influence the rate at which the body produces cholesterol, the rate at which the cholesterol is deposited, and the incidence of heart attacks. In general, those fats that are considered saturated because there are few double bonds between their carbon atoms tend to increase the deposition of cholesterol. Such fats include coconut oil and those that are hard at ice-box temperatures. The unsaturated fats include most vegetable oils that have not been hydrogenated; fish oils also belong to this group. These fats remain liquid at icebox temperatures. Chicken fat is intermediate between these two groups in degree of saturation.
The evidence that substituting unsaturated for saturated fats in the diet will lower the incidence of heart attacks and other cardiovascular diseases is not yet conclusive, but it is impressive. Experimental evidence on several species of animals and preliminary results on studies in man support this theory. Therefore, many doctors now recommend the substitution of unsaturated fats for saturated fats in the diet.