Cholesterol is a steroid produced in your liver or your gut used to synthesize hormones and cell membranes. Your body transports cholesterol in your blood plasma as triglycerides and lipoproteins known as very low-density, low-density, high-density and intermediate density lipoproteins. Medical professionals consider the lipoproteins with the lower densities as bad cholesterol.
Formation of Cholesterol
Exogenous cholesterol is absorbed each day from your gastrointestinal tract. However, the cells in your body form an even greater quantity of cholesterol known as endogenous cholesterol. Most the endogenous cholesterol that circulates in the lipoproteins of your plasma form in your liver. Important factors that affect plasma cholesterol concentrations include the amount of cholesterol you ingest each day, the amount of saturated fat in your diet, ingestion of highly unsaturated fatty acids and lack of insulin or thyroid hormones in your body.
Cholesterol Metabolism
Your body absorbs almost all the fats in your diet from your intestines into your intestinal lymph as chylomicrons, molecules containing phospholipids, cholesterol and apoprotein B. Your liver oxidizes cholesterol into bile acids and then excretes a mixture of bile acids along with cholesterol into the bile. According to "Guyton and Hall Textbook of Medical Physiology," your body reabsorbs approximately 95 percent of the bile acids from the intestines and eliminates the remainder through feces. This excretion and reabsorption process helps your body digest and absorb dietary fats.
Pharmacological Application
Elevated lipoproteins levels of the lower densities varieties can lead to cardiovascular diseases such as heart attacks, atherosclerosis and strokes. Doctors use several pharmacological treatments including statins, fibrates, resins, niacin, inhibitors of intestinal cholesterol absorption and omega-3 fatty acids to treat elevated lower density lipoproteins. Resins are sequestering agents that prevent bile acid reabsorption. Since your bile also contains cholesterol, resins also inhibit the reabsorption of cholesterol.
Other Applications
According to "Harrison's Principles of Internal Medicine," you can help prevent cholesterol reabsorption and lower LDL levels by consuming soluble fiber found in oats, barley, legumes and fruits and vegetables with skins. In addition, plant sterols can also help prevent cholesterol reabsorption in your body. You can find plant sterols in specific margarines, milks and yogurts. Sheila Doggrell, biomedical writer and pharmacologist, states that the margarines and spreads on the market are not effective enough to make any difference once a doctor diagnoses you with abnormally high levels of cholesterol. Further, these products provide no benefit to people whose cholesterol falls within the normal range.
References
- SMH: Spread the Word: Medicinal Margarine not Worth the Money; Paris Cowan; January 2011
- "Guyton and Hall Textbook of Medical Physiology"; John E. Hall; 2010
- "Human Physiology: The Mechanisms of Body Function"; Arthur Vander et al; 1998
- "Harrison's Principles of Internal Medicine"; Dennis Kasper et al; 2004
