High dairy intake is linked to prostate cancer

High levels of dairy and calcium consumption are associated with increased risk of prostate cancer, according to research published this month in the Journal of the National Cancer Institute. The authors, Xiang Gao, Michael LaValley, and Katherine Tucker used data from the the best already existing prospective scientific analyses. The research was part of Xiang Gao's recently completed dissertation (I served on his Ph.D. committee and discussed one of the other papers from the dissertation here).

The Dietary Guidelines for Americans 2005 recommends that Americans increase their intake of dairy products. However, some studies have reported that increasing dairy product intake is associated with an increased risk of prostate cancer. We conducted a meta-analysis to examine associations between intakes of calcium and dairy products and the risk of prostate cancer.... High intake of dairy products and calcium may be associated with an increased risk of prostate cancer, although the increase appears to be small.

The authors place these results in the context of the most recent Dietary Guidelines for Americans, which recommended increased dairy intake. That new recommendation was controversial, in part because of the possible link between dairy and prostate cancer (see Newsweek, for example, which quoted Harvard's Walter Willett raising these concerns). This dairy and prostate cancer connection motivated an earlier satirical advertising campaign by animal rights groups, featuring former New York City mayor Rudy Giuliani without his permission, along with the slogan, "Got Prostate Cancer?." The federal government heavily promotes dairy through checkoff advertising programs, which make no effort to provide balance about the respective advantages and disadvantages of the advertised products.

The new research by the Tufts researchers received extensive press coverage this month (see WebMD and ABC's affiliate).