A very large study of over 20,885 men was published in American Journal of Clinical Nutrition; Dec 22 2008 that showed that eating dairy products often may be a risk factor for prostate cancer and advanced prostate cancer.

Lead researcher, Edward L Giovannucci, at the Harvard Medical School showed that men who consumed more than 2.5 servings of dairy products daily were 34 percent more likely to be diagnosed with prostate cancer than those who consumed less than 0.5 servings.

The study was a pat of the Physicians’ Health Study, a cohort of male US physicians that were followed over an eleven year time period. Over te eleven years 1,012 were diagnosed with prostate cancer.

The study design estimated dairy calcium intake on the basis of consumption of 5 dairy products including cold breakfast cereal, whole milk, and skim milk, cheese and ice cream. These 5 dairy products were the main sources of dietary calcium for the study population.

The researchers found each additional 500 mg of calcium from dairy products per day was associated with a 16 percent increase in the risk of prostate cancer. The association was similar even intake of other foods such as chicken, fish, and eggs was considered.

They also found that when the 5 dairy foods were considered individually, skim milk was significantly positively as it related to prostate cancer and men who consumed one or more servings per day. These higher consumers were 32 percent more likely to have prostate cancer than those who did not consume any dairy products.

Skim milk accounted for 48 percent of total dairy product intake and 57 percent of the total dairy calcium intake.

Men who had the highest intake of dairy products were 38 and 42 percent more likely to have advanced and non- advanced prostate cancer