Environmental and Lifestyle Influences

More than half of all American adults have total cholesterol levels over 200, with 20% having levels over 240. This large percentage of Americans with high cholesterol levels is disturbing when compared to that of Asians and people in the South Pacific, which is only about 7%. In one study, Japanese children, who exercise regularly and have diets that are low in fat and high in soy products, had significantly higher HDL levels than American or Australian children. Simply having been raised in the American culture, then, is a risk factor for unhealthy cholesterol levels. It is generally believed that the typical high-fat, high-cholesterol, high-protein, low-fiber, American diet is largely responsible for this unfortunate statistic. Obesity and a sedentary life style add to the risk. A recent study reported that any weight gain, regardless of whether a person is overweight, can worsen cholesterol levels. 

Gender

On average, men develop coronary artery disease ten to 15 years earlier than women do, but coronary artery disease is still the number one killer of women. Women between the ages of 20 and 34 and after menopause -- around age 55 -- have higher cholesterol levels than do men. In spite of this, one study reported that while 60% of women with heart disease had high LDL levels, fewer than half of them were being treated with cholesterol-lowering medication, and most of those who were on medication were not being given adequate treatment. One study suggested that HDL levels might be more significant for women than LDL levels; at total cholesterol levels above 200, women with HDL levels below 50 had a higher death rate than those with levels above 50, regardless of their LDL cholesterol levels. Triglycerides also may be a more significant factor in women than in men.

 Age

Children and Adolescents. Not even young people are exempt from dangerous cholesterol levels, although, the good news is that average cholesterol levels in American young people has fallen over the past 30 years, mostly due to lower fat intake. Still, in the study reporting this trend, the highest cholesterol levels were in a younger group of children (ages 9 to 11), and African American girls experienced only a very small decline (about 4 mg/dL.). The study also concluded that five out of six American young people still consume too many fats.

Older Adults. The effects of high cholesterol in people over 70 and how to treat it are very controversial issues. A number of studies report that in older adults, high cholesterol levels pose a significant risk for death from coronary artery disease. Other studies, however, have reported that lowering cholesterol levels in the elderly may increase the risk for stroke. In people over the age of 85, high cholesterol levels are associated with greater longevity and a significantly lower risk from infection and cancer. It is not clear, however, whether such cholesterol levels increased later in life or whether they had persisted for years. Developing high cholesterol levels late in life would most likely not damage the heart before the person has died of other causes. To complicate matters, studies indicate that cholesterol levels naturally drop with age regardless of weight, medications, or lifestyle.

 Genetic Factors

Genetics play a major role in determining a person's blood cholesterol levels, and children from families with a history of premature heart disease should be tested for cholesterol levels after age two. Genes may influence whether one has low HDL levels, high LDL levels, or high levels of other lipoproteins, such as lipoprotein(a). Two studies have found a genetic mutation affecting neuropeptide Y (an enzyme that regulates appetite) in people with high total cholesterol and LDL levels. One study found the mutation in both obese people and those of normal weight while the other found it only in obese individuals. A rare inherited disease called heterozygous familial hypercholesterolemia causes extremely hazardous cholesterol levels Children from families with a history of premature heart disease should be tested for cholesterol levels after age two.