Cholesterol:The most common type ofsteroidin the body.Cholesterolhas a reputation for being associated with an increased risk for heart and blood vessel disease. However, cholesterol isessentialto the formation ofbileacids,vitamin D,progesterone,estrogens(estradiol, estrone, estriol), androgens (androsterone,testosterone), mineralocorticoid hormones (醛固酮皮质甾酮)ndglucocorticoidhormones (cortisol). Cholesterol is also necessary to the normal permeability and function of the membranes that surround cells. A diet high in saturated fats tends to increase blood cholesterol levels, whereas a diet high in unsaturated fats tends to lower blood cholesterol levels. Although some cholesterol is obtained from the diet, most cholesterol is made in the liver and other tissues. The treatment of elevated cholesterol involves not only diet but also weight loss, regular exercise, and medications.
