Cholesterol: the good, bad and the ugly Published Sept. 6, 2007 By David Hey, Ph.D. 319th Health and Wellness Center GRAND FORKS AIR FORCE BASE, N.D. -- September is National Cholesterol Month and soon doctors from around the country shout "watch your cholesterol numbers!" Yet some people remain confused about what cholesterol is and where it comes from. After all there are both "good" and "bad" forms of cholesterol, that you should be familiar with. First, the good Many people are surprised to learn that cholesterol has a number of essential functions in the human body. It is used in tissue repair, for strengthening cell membranes and for the manufacture of bile salts, steroid hormones (including the sex hormones -- estrogen and testosterone), and vitamin D production. There is little danger of cholesterol deficiency because it can be manufactured in the liver from fats, carbohydrates and proteins. So, like that of some foods we consume that get a bad rap (i.e., fat), we must have cholesterol to survive and thrive. How much we eat is key. The bad Cholesterol is a waxy fat that can form thick deposits, known as plaques, on blood vessel walls. Thus, a high total cholesterol level in the blood is associated with heart disease. How does this happen? The plaques make the vessel harder and restrict or obstruct blood flow though it, which ultimately can lead to a heart attack. Your liver produces cholesterol in your body and the rest comes from the animal products you eat. Fruits and vegetables do not contain cholesterol, although vegetable oils do contain fat. Saturated fats come mainly from animal sources (such as beef, butter, whole-milk dairy products, the dark meat of poultry, and poultry skin) as well as some tropical vegetable oils (such as coconut and palm oils). So, we need to keep a handle on our saturated fat consumption. The good and the bad - which is which? Our blood has two kinds of cholesterol: high density and low density. High density is the good kind of cholesterol because it protects us from heart disease. It is thought that HDL helps carry cholesterol away from the vessels and back to the liver. Low density lipoprotein is the bad kind, or heart-attack-causing cholesterol because it encourages plaque formations. As a result, you need to know your total cholesterol level and the amount of both good and bad cholesterol in your blood to determine your risk of heart disease. The ugly Diets high in fat, especially saturated fat, are associated with higher cholesterol numbers. Eating a diet containing no more than 30 percent of calories from fat is one method used to help prevent development of high cholesterol. Foods particularly rich in cholesterol include eggs, dairy products and meats. The problems associated with cholesterol arise because modern diets in northern Europe and North America often result in over-production. A lot of cholesterol is not used but is deposited in the walls of blood vessels where it increases the risk of coronary heart disease and atherosclerosis. The most influential factor in raising blood cholesterol levels is eating foods high in saturated fat. Nicotine increases deposition of cholesterol in the walls of blood vessels. Hereditary factors are also important determinants of blood cholesterol levels. Diet and exercise--key to healthy cholesterol levels A good diet can decrease blood cholesterol levels. Soluble fiber, polyunsaturated fat (especially fish fats which contain omega-3 fatty acids), and monounsaturated fat (such as olive oil) may all lower cholesterol levels. Regular aerobic exercise also helps to reduce deposition of cholesterol in blood vessels. Clinical assessment Blood cholesterol levels vary considerably and there is no universally accepted safe level, but the following are guidelines used by most doctors: CHOLESTEROL LEVELS desirable levels <5.2 mmol/l (<200 mg/dl) slightly raised 5.2-6.4 mmol/l (200-250 mg/dl) high 6.5-7.8 mmol/l (251-300 mg/dl) very high >7.8 mmol/l (>300 mg/dl) Did you know you can test your own cholesterol? Several cholesterol test-kits can be bought over the counter. If used properly, these can give quite accurate readings, but interpreting the results is not easy, and the results may make a person unnecessarily anxious. A number of factors can affect blood cholesterol levels temporarily. Exercising or eating before the test can raise levels by more than 15 percent. It is normal for cholesterol levels to fluctuate, so at least two tests, separated by one or two months, are needed to give a reliable average. People who are worried about their cholesterol level should have it checked properly by their physician. Proof in the pudding The relationship between dietary fats and CVD, especially coronary heart disease, has been extensively investigated, with strong and consistent associations emerging from a wide body of evidence accrued from animal experiments, as well as observational studies, clinical trials and metabolic studies conducted in diverse human populations. Saturated fatty acids raise total and low-density lipoprotein (LDL) cholesterol. The most effective replacement for saturated fatty acids in terms of coronary heart disease outcome are polyunsaturated fatty acids, especially linoleic acid. This finding is supported by the results of several large randomized clinical trials, in which replacement of saturated and trans fatty acids by polyunsaturated vegetable oils lowered coronary heart disease risk. Source: - World Health Organization, Population nutrient intake goals for preventing diet-related chronic diseases, 5.4.4(2007)