Selasa, 28 Juni 2011

Cholesterol and Heart Disease - The Good, the Bad and the Ugly

"And if you have high cholesterol, you would feel the same as if you had low cholesterol because there are no side effects, no symptoms of having high cholesterol. " Mark Spitz, winner of 9 Olympic gold medals in swimming.

Heart disease remains the leading killer of men and women in the United States. Each year, 1,200,000 people suffer a coronary heart attack, and about 40% of them die. An American dies of a coronary event roughly every 65 seconds. Abnormal cholesterol, besides smoking, diabetes, high blood pressure, obesity and physical inactivity, remains one of the main modifiable risk factors for coronary heart disease.

"I drive way too fast to worry about cholesterol." Comedian Steven Wright. But we should. Abnormal cholesterol levels can clog up your arteries. There are several hundred studies confirming the dangerous health effects of abnormal cholesterol levels. The Framingham Heart Study found that under age 50, total cholesterol levels directly correlated with 30-year overall and cardiovascular mortality. For each 10 mg/dl increase in cholesterol, there is an overall increase in death of 5% and cardiovascular death of 9%. Abnormal cholesterol levels are also implicated in contributing to stroke, limb amputation, erectile dysfunction, Alzheimer's disease and kidney failure.

Cholesterol is not totally a bad thing. Cholesterol keeps cell membranes fluid, flexible and functional. Cholesterol helps in the manufacture of bile, and thereby helps in the digestion of fats. It is also important for the metabolism of fat soluble vitamins, including vitamins A, D, E and K. It is involved as a major precursor in the synthesis of vitamin D and many steroid hormones, including the adrenal hormones cortisol and aldosterone, and the sex hormones progesterone, estrogen, testosterone, and their derivatives. Cholesterol is water insoluble, and is carried to its destinations by lipoproteins. About 80% of the cholesterol is made by the liver via carbohydrate metabolism through the HMG-CoA reductase pathway. This amounts to about 1000 mg per day. Diet in the Western countries adds about 200 - 300 mg for intestinal intake. Most of dietary cholesterol comes from animal food, including meat, poultry, fish, egg yolk, butter, cheese and whole milk. Trans fats are hydrogenated fats and are found in margarine and many commercially prepared processed and deep fried foods like cookies, cakes, crackers, french fries and donuts. These are also unhealthy and consumption is associated with atherosclerosis. Plant sources of food ( fruits, vegetables, nuts and cereals ) are free of cholesterol. Phytosterols found in certain plant products like flax seed and peanuts may actually help lower serum cholesterol. However, cooking oils of plant origin, especially palm and coconut oil, are high in saturated fats and are heart unhealthy. But there's another kind of fat called essential fatty acids. These are unsaturated fats and include omega-3 and omega-6 fats. These help are cell membranes and are required for the production of certain hormones that are essential for blood clotting, blood pressure control, and eye and brain function. Overall, they lower blood pressure and cholesterol, and reduce mortality from heart disease.

"Somewhere, over the rainbow, way up tall, there's a land where they've never heard of cholesterol." Musician Allan Sherman. However, in the real world, we have to monitor its levels. Total cholesterol should be measured after a 9 to 12 hour fast. A level of less than 200 mg/dl is desirable. A level of 200 to 239 mg/dl is borderline high and a level above 240 mg/dl is associated with a higher risk of coronary heart disease. However, a lipoprotein analysis is more reliable as it better profiles the risk. A lipid profile gives the levels of the bad low density lipoprotein (LDL) cholesterol, the good high density lipoprotein (HDL) cholesterol and the triglycerides. LDL levels should ideally be less than 100 mg/dl. Levels over 160 are high and associated with an increased risk of heart disease. HDL provides protection against heart disease if it above 60 mg/dl. A level less than 40 mg/dl is associated with increased heart disease. Triglyceride levels should be less than 150 mg/dl. Higher levels, especially when associated with abnormal LDL or HDL levels, increase your risk of heart disease.

Does lowering cholesterol help? Scientific medical literature is filled with research data confirming the beneficial effects of lowering cholesterol. A 1995 study called the West of Scotland Coronary Prevention Study (WOSCOPS) followed 6500 men with high cholesterol levels for 5 years. One half the people were given a cholesterol reducing statin drug, provostatin, while the other were given a placebo. The drug reduced the total cholesterol levels by 20 percent and the bad LDL cholesterol levels by 26 percent. The heart attack risk was reduced by 31 percent in those receiving the statin drug. The need for bypass surgery or angioplasty was reduced by 37 percent. Overall deaths from all causes were reduced by 22 percent, and deaths from cardiovascular causes by 32 percent. In 1998, the results of the Air Force/Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TexCAPS) showed that cholesterol lowering with another statin drug, lovastatin, also reduced the risk of a first major coronary event by 37 percent when given to generally healthy men and women with average cholesterol levels. The total cholesterol levels in the treatment group were lowered by 18 percent and LDL-cholesterol levels by 25 percent, after a year of treatment. Like in the WOSCOPS study, significant reductions in events were also noted: heart attack was reduced 40 percent, unstable angina 32 percent, the need for bypass surgery or angioplasty 33 percent, and all cardiovascular events 25 percent. Recent scientific data suggests that higher doses of statins may provide even greater benefits.

The commonly used drugs to lower high total cholesterol or the bad LDL cholesterol are statins. The statins lower cholesterol by inhibiting the enzyme HMG-CoA reductase, which is the rate-limiting enzyme in cholesterol synthesis. Inhibition of this enzyme in the liver results in an increased clearance of LDL from the bloodstream and a decrease in blood cholesterol levels. Results are seen as early as after one week. Maximal effect occurs after four to six weeks. There are over ten statin drugs available commercially in the United States. Other agents are also available to reduce total cholesterol and LDL levels and act mainly by preventing absorption of the cholesterol in the intestines. They are often used in combination with the statins. Although the statins can raise the good HDL cholesterol, this effect is small. HDL can be raised by the common vitamin niacin. A class of drugs called fibrates not only help raise HDL but also help lower triglycerides.

There are many ways to improve the lipid profile without drugs. Reduce the amount of animal fats and saturated fats you consume. Regular exercise and weight loss not only will help reduce the LDL and triglyceride levels, but also raise the good HDL levels. Moderate alcohol intake also increases HDL cholesterol .Eating more fruits and vegetables and consuming more monounsaturated fats also improves the lipid profile. Remember, our health always seems much more valuable after we lose it. So let us listen to the motivational speaker Jim Rohn, who said, "Take care of your body. It's the only place you have to live."

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