Drinking low-fat or nonfat milk does not increase a person's risk of developing heart disease or having a stroke, and it may even be slightly protective, a new study suggests.

Researchers in the U.K. found that middle-aged men who drank the most milk had the same rate of heart attacks, strokes, and deaths from all causes as men who drank the least over two decades of observation.

Drinking more than 7 ounces of milk a day was associated with a 10 percent decrease in heart attack risk compared with drinking less milk. But researcher Andy Ness, MD, says it is not clear if this protective effect is real.

"We found no evidence that drinking modest amounts of milk as part of a balanced diet had any detrimental effect on health," he tells WebMD. "But I would not encourage people to drink large quantities of milk based on this study to decrease their cardiovascular risk. That would be the wrong message."

Evidence Shows Little Risk

Antimilk groups like People for the Ethical Treatment of Animals contend that dairy consumption is a major cause of heart attacks and strokes in the U.S. An essay entitled "Got Heart Disease?" found on the group's web site charges that "study after study has implicated cow's milk and other dairy products as a cause of heart disease and clogged arteries."

But the clinical evidence shows little or no association between low-fat and nonfat dairy consumption and cardiovascular risk, American Heart Association spokesman Gerald Fletcher, MD, tells WebMD. Fletcher directs the preventive cardiology program at the Mayo Clinic in Jacksonville, Fla.

An analysis of 10 studies examining milk consumption and heart attacks and strokes, published by Ness and colleagues last year, showed no evidence of increased cardiovascular risk in milk drinkers. Like their own research, the studies suggested that drinking milk may be associated with a small reduction in heart disease and stroke risk. But the finding was not conclusive.

"Certainly high-fat dairy products can be a problem in terms of raising cholesterol levels," he says. "But low-fat dairy doesn't seem to have much impact one way or the other."

Blood Pressure, Cholesterol, and Milk

The new study included 665 men between the ages of 45 and 59 recruited for an ongoing nutrition and health study between 1979 and 1983. Just after recruitment the men were asked to weigh and record everything they ate or drank for one week. They were then followed for evidence of heart disease for the next 20 years, during which time 54 of the men had strokes, 139 developed heart disease, and 225 died.

Most of the men drank whole milk when they entered the study, but almost all had switched to skim or low fat two decades later.

Men who drank the most milk (a pint or more) and the least milk (less than half a pint) had similar blood pressure and cholesterol levels. Men who drank the most milk also consumed the most calories, while men who drank the least milk drank the most alcohol.

Death rates from all causes were similar in both groups. Men who drank the most milk had a lower risk of stroke caused by blood clots than those who drank the least. They also tended to have a slightly lower risk of heart attack than those who drank less.

The study is published in the latest issue of the Journal of Epidemiology and Community Health.

3 Servings a Day

Government nutrition guidelines were recently changed to recommend that adults eat three servings of nonfat or low-fat dairy products a day instead of two. And the American Heart Association and the National Heart Lung and Blood Institute recommend nonfat or low-fat dairy products as part of a healthy diet.

National Dairy Council spokeswoman Teresa Wagner says recent studies suggest that milk consumption improves blood pressure and insulin resistance -- a marker of heart disease and a risk for developing diabetes. Just two weeks ago nutrition researchers from the Harvard School of Public Health reported that drinking milk helps protect against type 2 diabetes.

"I think people now realize that low-fat and fat-free dairy products can provide a lot of health benefits," she tells WebMD. "They recognize the unique nutrient package of dairy foods, which includes not only calcium but eight other essential vitamins and minerals that may play a role in other aspects of health besides just bones."

By Salynn Boyles, reviewed by Brunilda Nazario, MD

SOURCES: Elwood, P.C. Journal of Epidemiology and Community Health, 2005; vol 59: pp 502-505. Andy Ness, MD, senior lecturer in epidemiology, University of Bristol, England. Gerald Fletcher, MD, director of preventive cardiology, Mayo Clinic, Jacksonville, Fla. Teresa Wagner, RD, spokeswoman, National Dairy Council. People for the Ethical Treatment of Animals: "Got Heart Disease?"