Dec. 6, 2005 -- Men who consume large amounts of milk or other dairy products may have a slightly higher risk of developing prostate cancer than men who don't, according to a new research review.
Government dietary guidelines released earlier this year recommend that all adults eat 3 cups of fat-free or low-fat milk or equivalent milk products a day. This includes a cup of low-fat or fat-free milk or yogurt, 1.5 ounces of natural cheese, or 2 ounces of processed cheese.
But the authors of the newly published study question whether the revised recommendations are appropriate for adult men.
"Given the high prevalence of prostate cancer in American men ... these findings suggest caution before one embraces the new recommendations to increase dairy intake, especially among older men," they wrote in the Dec. 7 issue of the Journal of the National Cancer Institute.
Small Risk, Common Cancer
The researchers reviewed 12 studies, conducted between 1966 and 2005, which examined dairy and calcium intake and prostate cancer incidence.
They report that men who ate the most dairy products had an 11% increase in prostate cancer risk compared with men who ate the fewest. Men with the highest intake of calcium were 39% more likely to develop prostate cancer than men with the lowest.
The risk increases reported in the studies were modest. But an author of the latest work tells WebMD that it is potentially significant because prostate cancer is so common.
Prostate cancer is the most widely diagnosed cancer among American men. According to the American Cancer Society, one out of six men will develop the disease. One out of 34 men will die from the disease.
"Even though the risk is small, this could be a big problem," says Xiang Gao, PhD. Gao conducted the analysis while at Tufts University's Jean Mayer USDA Human Nutrition Research Center on Aging.
"I think the new dairy guidelines are good for young people who need calcium, but they may not be appropriate for older men."
An Unanswered Question
American Cancer Society senior epidemiologist Marji McCullough, ScD, says the role of dairy and/or calcium in prostate cancer is still very much an open question.
She adds that studies examining dietary influences in prostate cancer risk and survival are now under way.
"We still need to learn a lot more about how dietary factors influence cancer development and survival among men who have prostate cancer," she tells WebMD.
National Dairy Council spokeswoman Teresa Wagner, RD, agrees that more research is needed to determine if dairy and/or calcium plays a role in prostate cancer, noting that the vast majority of studies reported to date have major design limitations.
The new guidelines calling for three servings of dairy a day have been endorsed by the U.S. Surgeon General, the American Dietetic Association, the American Academy of Family Physicians, and other health groups.
"The health benefits of calcium and the other eight essential vitamins and minerals found in dairy foods are clear," she says.