Author John Abramson states in his book, Overdosed America: "Statins show a clear benefit for one group: People under 65 who have already had a heart attack or have diabetes. But even in these very high risk people, about 22 have to be treated for five years for one to benefit."

What about middle-aged people who are not diabetic and have not had a heart attack? A 2006 study published in the Annals of Internal Medicine that focused on seven trials involving nearly 43,000 middle-aged adults concluded that statin use did not cut their chances of dying from heart disease.

Is there any group that can benefit from a statin? According to Abramson, "If they are high risk, statins can be beneficial to people under 65 who haven't had a heart attack, but 50 such men have to be treated for five years for one to benefit. The other 49 will not be helped. And all 50 will be exposed to the side effects."

Older adults have little to gain. The drugs don't help people over 70 even if they have elevated cholesterol levels, according to a report in the Journal of American Cardiology.

Finally, there is no evidence of any benefit for women who don't already have heart disease or diabetes. According to a 2004 article published in the Journal of the American Medical Association which reviewed all trials in which women with high cholesterol had been randomly assigned to take a cholesterol-lowering drug or a placebo, there was no evidence that statins prolonged women's lives or cut their chances of dying from heart disease.