IV.

Risk Factors

Some of the risk factors for coronary heart disease are beyond a person’s control. For example, a person’s risk of developing coronary heart disease increases with age. Hereditary factors may also increase the risk for the disease. Males were once thought to be at greater risk of coronary heart disease, but more recent studies show this is not true. About equal numbers of women and men develop coronary heart disease. Heart attacks in women are more likely to be fatal than in men. Women tend to develop the disease later in life than men do. This is because the sex hormone estrogen that circulates in women’s bodies helps protect them against atherosclerosis. Therefore, most women do not develop coronary heart disease until after menopause, when levels of protective estrogen markedly decrease.

Other risk factors for coronary heart disease can be changed depending on a person’s lifestyle. These modifiable risk factors include cigarette smoking, a sedentary lifestyle, obesity, diabetes mellitus, and hypertension (high blood pressure). Perhaps the most important modifiable risk factor, however, is high blood cholesterol. When excess cholesterol circulates in the blood, it deposits in the wall of the arteries, hastening the progression of atherosclerosis.

The amount of cholesterol in a person’s bloodstream is partially determined by heredity, but it also depends on the amount of cholesterol and animal fat in the diet (see Human Nutrition). In some parts of Asia and Africa where people consume very little fat and cholesterol, total blood cholesterol averages less than 150 milligrams per deciliter (mg/dl) and heart attacks are very rare. In the United States, where the typical diet includes many foods high in fat and cholesterol, total blood cholesterol averages about 200 mg/dl, and coronary heart disease is the leading cause of death.

Scientists have learned that cholesterol is especially dangerous when it is carried through the bloodstream as low-density lipoprotein (LDL), which is often known as “bad” cholesterol. By contrast, cholesterol in the form of high-density lipoprotein (HDL) actually lowers a person’s risk of heart attack, and HDL is often referred to as “good” cholesterol.