Cholesterol is present in nearly every cell in your body. It serves an essential role in maintaining the flexibility and permeability of cell membranes, and it is the precursor for bile acids, vitamin D and steroid hormones, such as testosterone and estrogen. However, in 1961, researchers at the National Heart, Lung and Blood Institute and Boston University determined that a high cholesterol level increases your risk for heart disease.
According to Dr. Elson Haas, author of "Staying Healthy With Nutrition," your brain is the only tissue that does not manufacture its own cholesterol. While your liver is the primary site of cholesterol production, all of your other cells can synthesize their own cholesterol from fatty acids, with the help of an enzyme called HMG-CoA reductase. This process is regulated by how much cholesterol is present in your system, which is in turn influenced by your dietary patterns.
Inhibiting Cholesterol Synthesis
Once scientists had demonstrated cholesterol's role in cardiovascular disease, drug manufacturers were quick to capitalize on the notion that lowering your cholesterol could decrease your risk for heart attacks and strokes. Medications that bound cholesterol in the intestine or slowed its release from the liver were first to get to market. In 1987, the first "statin" drug that inhibited HMG-CoA reductase was approved by the U.S. Food and Drug Administration. Several other statin drugs soon followed.
Daily Variation in Cholesterol Production
Whenever you eat, the cholesterol that is derived from your food suppresses the synthesis of new cholesterol in your tissues, particularly in your liver. Therefore, cholesterol production tends to follow a diurnal pattern, with the highest production occurring at times of fasting. For most people, the period of highest cholesterol production takes place at night. A 2003 "British Medical Journal" review suggests that this diurnal variation in cholesterol synthesis may impact the effectiveness of drug therapy for high cholesterol.
Considerations and Recommendations
Most manufacturers of statin drugs recommend that you take these agents at bedtime to take advantage of normal diurnal changes in cholesterol synthesis. However, some statins, such as atorvastatin, are eliminated from your body more slowly than others, so their therapeutic effect lasts longer. A 1996 study in the "Journal of Clinical Pharmacology" suggested that atorvastatin seemed to be just as effective whether it was taken in the morning or evening. If you take a medication to lower your cholesterol, follow your doctor's or pharmacist's directions.