Cholesterol and Heart Disease
Heart disease or cardiovascular disease (CVD) is the primary cause of death in the United States. Each year, more than one million Americans have heart attacks, and half a million die from heart disease. The chance of developing heart disease or having a heart attack increases as your level of blood cholesterol increases.
Cholesterol is a fatty substance produced mainly by the liver and intestines. Cholesterol is a constituent of cell membranes, and it is used by the body to produce bile acids and steroid hormones such as testosterone, estradiol, progesterone, and cortisol. Exposure of the skin to direct sunlight converts cholesterol to vitamin D, which is necessary for bone development. Besides being produced by some organs, cholesterol can also originate from foods of animal origin such as meats, fish, and dairy. Cholesterol travels through the bloodstream in compounds called lipoproteins. Low-density lipoproteins (LDL or "bad" cholesterol) deliver cholesterol to the body, whereas high-density lipoproteins (HDL or "good" cholesterol) take cholesterol out of the bloodstream. Hyperlipidemia is an elevation of lipids in the bloodstream. These lipids include cholesterol, cholesterol esters, phospholipids, and triglycerides.
Excess cholesterol builds up gradually in the walls of the arteries causing atherosclerosis or "hardening of the arteries". The cholesterol plaques narrow the arteries and decrease the blood flow that can reach the heart. Chest pain (angina pectoris) usually occurs during exertion when the heart muscle requires more blood oxygen than can be delivered by the narrowed coronary arteries. A heart attack occurs when a cholesterol plaque ruptures and mixes with blood to form a clot that completely blocks blood flow to the heart muscles.
Your Cholesterol Numbers
A blood test called a "lipoprotein profile" or "lipid panel" is used to determine your cholesterol numbers. This test is done after a 9- to 12-hour fast. The Total Cholesterol (TC) value is obtained using a formula called the Friedewald equation (named for William Friedewald, who developed it) by adding the LDL, the HDL, plus one fifth of the value of the triglycerides (TG), i.e., (TC = LDL + HDL + TG/5) when the values are in milligrams (mg) per deciliter (dl) of blood. The numbers in parentheses are in millimoles per liter. The following table summarizes the interpretation of the numbers.
|Less than 200 mg/dl (5.2 mmol/l)||Desirable|
|200-239 mg/dl (5.2-6.2 mmol/l)||Borderline high|
|240 mg/dl (6.3 mmol/l) and above||High|
|LDL Cholesterol Level|
|Less than 100 mg/dl (2.6 mmol/l)||Optimal|
|100-129 mg/dl (2.6-3.3 mmol/l)||Near optimal|
|130-159 mg/dl (3.4-4.0 mmol/l)||Borderline high|
|160 mg/dl (4.1 mmol/l) and above||High|
|HDL Cholesterol Levels|
|Less than 40 mg/dl (1.0 mmol/l)||Heart disease risk factor|
|40-59 mg/dl (1.0-1.5 mmol/l)||Normal range|
|60 mg/dl (1.6 mmol/l) and above||Lower risk of heart disease|
|Less than 150 mg/dl (1.7 mmol/l)||Normal|
|150-199 mg/dl (1.7-2.2 mmol/l)||Borderline high|
|200 mg/dl (2.3 mmol/l) and above||High|
What causes high cholesterol?
High blood cholesterol is generally caused by bad diet, but 1 in every 500 cases may be due to genetic causes (familial hypercholesterolemia). Eating foods that are high in saturated fats and hydrogenated oils cause the liver to produce more LDL cholesterol that increases your cholesterol numbers. If the foods that you eat are also high in cholesterol, and if you don't have sources of soluble fiber, phytosterols, and polyunsaturated fats in your diet, you end up with high blood cholesterol. The cholesterol problem can get worse and your risk of cardiovascular disease increases if you are overweight, don't exercise, or you smoke.
There is a pill for that.
The general public, as well as doctors, are inundated with advertisements from pharmaceutical companies promoting cholesterol-lowering drugs. Once a blood test shows a high level of cholesterol, a doctor will usually not hesitate to prescribe one of the following drugs (trade names in parentheses): lovastatin (Mevacor), simvastatin (Zocor, Lipex, Simvar, Vytorin), pravastatin (Pravachol), atorvastatin (Lipitor), fluvastatin (Lescol, Vastin), and rosuvastatin (Crestor).
The prevailing philosopy seems to be that people do not have enough self-restraint to change their life style. It is much easier for them to take one pill every day in spite of the possible adverse effects of the drugs. Unfortunately, people are seldom offered information about how they can help themselves without resorting to using drugs for the rest of their life.
How can you lower your cholesterol with lifestyle changes?
The National Cholesterol Education Program established by National Heart, Lung, and Blood Institute of the NIH says that reducing the amount of saturated fat and cholesterol in your diet helps lower your blood cholesterol level. The program advocates Therapeutic Lifestyle Changes (TLC) which consist of:
A competent dietician or a metabolism expert can probably deduce why these recommendations can lower cholesterol. However, the information contained in these guidelines is not enough to enable the average person to get a scientific foundation for guiding their nutritional and lifestyle choices. Weight management and physical activity are discussed in different sections. The following paragraphs describe the scientific basis for the dietary recommendations in simple terms.