Doctors are divided about the benefits and risks of statins against heart disease. On one side are the enthusiasts who believe that almost everyone over the age of 50 should be on a drug like atorvastatin or simvastatin. On the other side are the statin skeptics who are unconvinced that otherwise healthy people truly benefit from taking medications that can cause side effects.

After 27 years of experience with statins, you’d think that doctors would agree about their value. Tens of millions of people take such drugs every day. Most assume that their statin will save them from a heart attack. The data are much less clear.

Harlan Krumholz, M.D., wrote in The New England Journal of Medicine (April 24, 2014) that statins can lower the risk of a heart attack or stroke by about 20 percent, even in people who don’t currently have heart disease. Just one catch: 50 or 60 such people need to take statins every day for 10 years to prevent one heart attack.

New guidelines from the American Heart Association and the American College of Cardiology encourage doctors to prescribe statins to nearly one-third of adult Americans. Most older people would be candidates for these medications.

Not everyone agrees that statins should be prescribed so widely. Cardiologist Rita Redberg, M.D., M.S., editor of the journal JAMA Internal Medicine, told our radio audience: “The whole focus on cholesterol and LDL is misguided because your risk for heart disease is not just about your cholesterol or LDL number. It’s really part of a big picture, and most of it is lifestyle; it is not related to your cholesterol level.”

If you think doctors disagree about the benefits of statins, the risks are even more contentious. An article in the European Journal of Preventive Cardiology (April 2014) concluded that except for a modest 20 percent increase in diabetes, statins don’t cause significantly more side effects than placebo. Headlines proclaimed that statins have virtually no side effects.

Other investigators disagree and point out that 5 percent to 20 percent of patients discontinue statins because of intolerable side effects (Current Opinion in Rheumatology, November 2013). Muscle pain, weakness, cognitive impairment, cataracts and peripheral neuropathy all have been linked to statin use.

More recent research has uncovered two unanticipated consequences of statins. When more than 3,000 men were tracked for several years with sophisticated devices that measured their physical activity, statin takers were significantly less active and more sedentary than others in the observational study (JAMA Internal Medicine online, June 9, 2014).

People on statins also have changed their eating habits. According to data on more than 27,000 adults from NHANES (the National Health and Nutrition Examination Survey), statin users were eating more prudently than the rest of us back in 1999, but by 2010 that difference had disappeared (JAMA Internal Medicine online, April 24, 2014). The extra calories and fat that people on statins were consuming led to significantly greater weight gain as well. This was an unexpected and unwelcome discovery.

If, after nearly three decades, doctors don’t agree about the benefits and risks of statins, it’s hardly any wonder that patients also are confused.