Nearly half of Americans whose cholesterol readings put them at higher risk of heart attack or stroke are not taking medication to drive down that risk, says a new study by the Centers for Disease Control and Prevention.

The study makes clear that public health authorities bent on preventing heart disease and stroke have their pick of a lot of low-hanging fruit. Worrisome cholesterol numbers are a strong risk factor in cardiovascular disease, which contributes to one in three deaths in the United States. And cholesterol-lowering treatment - generally with a low-cost statin medication - has been shown to drive down rates of heart attack and stroke.

All told, 44.5 percent of American adults likely to benefit from cholesterol-lowering drugs were not on one. But the cholesterol treatment gaps observed by the CDC were far more pronounced among minorities in the United States than among whites.

African Americans are most likely to have health conditions that make them candidates for cholesterol-lowering medications: 39.5 percent of American blacks are considered "eligible" for such treatment. But 54 percent of eligible U.S. blacks were not taking medications to limit their risk.

Among whites, 38.4 percent are eligible for such drugs, and 42 percent of that group took no cholesterol-lowering medication.

Among Mexican Americans, it is thought that roughly a quarter should be taking a cholesterol-lowering drug. But 52.9 percent of that group are not doing so.

Adult women who were eligible to take prescription cholesterol drugs were more likely than eligible men to be taking them (58.6 percent versus 53.9 percent). And among African Americans with no regular source of medical care, 94.3 percent of those eligible failed to take potentially lifesaving medication.

Side effects of cholesterol-lowering medications prompt some resistance among patients. Among those taking statin medications - the frontline treatment for high cholesterol - roughly one in 10 develops significant muscle pain and fatigue, and about one in 100 develops diabetes.

But the latest research found that lifestyle changes that can help reduce cardiovascular risk - and which have few worrisome side effects - were also not widely followed by adults who could benefit from them. Among the 78.1 million adult Americans who were either taking the medications or considered candidates for cholesterol-lowering treatment, 46.6 percent reported they had made lifestyle changes such as exercising more, losing weight, and eating a more heart-healthy diet.

While 37.1 percent reported making lifestyle modifications and taking medication, 35.5 percent reported they did neither.

Nearly 800,000 people die of cardiovascular disease in the U.S. each year, making strokes and heart disease the largest killer of Americans.