CHOLESTEROL - A crystalline substance of a fatty nature found in brain, nerves, liver, blood, and bile. When exposed to ultraviolet light can lead to the production of vitamin D. Cholesterol is also a precursor to adrenal gland hormones and sex hormones. Cholesterol, obtained only from animal food sources, is not necessary in the diet because the body can synthesize all the cholesterol that is required for other uses. High cholesterol has been shown to be a risk factor for the development of atherosclerosis the cause of heart disease and stroke. For total blood cholesterol: Less than 200 is desirable; 200 to 239 is considered borderline high; over 240 is considered high.