Milk and Cancer

Dear Dr. Bone,

Is it true that there is a difference in the risk for cancer if you drink whole milk instead of skim or 2%? My friends and I were discussing it at lunch. I thought the benefits of lower fat were all related to heart disease, but they say that whole milk also contributes to cancer. Who is right?

D.L.

Dear D.L.

The relationship between milk and cancer is complex. Countries whose inhabitants do not consume much milk seem to have lower incidences of certain cancers. For example, in Japan and Mongolia there is less breast cancer than in the United States. One of the reasons posited for this phenomenon is the presence of hormones in milk. In order for cows to produce more milk they are kept pregnant for prolonged periods of time. Milk from pregnant cows naturally has a higher estrogen content. Farmers also inject the cows with hormones. One in particular, recombinant Bovine Growth Hormone (rBGH), results in milk that contains higher amounts of Insulin-like Growth Factor, known as IGF-1. IGF-1 can be absorbed from the milk and stimulate cancer cells. Since hormones in milk are fat soluble, it would seem safer to drink low fat milk. On the other hand, conjugated linoleic acid, a natural anti-cancer molecule, is found at its highest concentration in whole milk as is calcium, a necessary building block for our bones.

The popular book called The China Study looks into the relationship between diet and cancer. I have many friends who became vegan after reading it because they were convinced that dairy consumption can be dangerous, not just for cancer, but for heart disease and other ailments too. A moderate by nature, I suggest that each person find their comfort level after assessing the data. It is unlikely that an occasional glass of milk or ice cream will cause cancer, but dietary modifications along with exercise, decreasing alcohol consumption, and controlling stress, should results in a longer, healthier life.

~ Dr. Bone