Few issues are as contentious as the relationship between milk or dairy products and cancer. There are two vociferous camps claiming, alternately, that milk products are harmful and should therefore generally be avoided, or that dairy (and by extension, other animal-derived foods) are salutary and may actually prevent cancer and other diseases.
Now a new study in the journal The Prostate lends further evidence for the “anti-milk” view. Scientists at the European Institute of Oncology, Milan, and the Université de Montréal, compared 197 prostate cancer (PC) patients with an equal number of men who did not have PC. The participants filled out a food frequency questionnaire, recording their consumption of over 200 food items. There turned out to be a more than twofold increase in the risk of prostate cancer associated with an increased intake of dairy products. At the same time, there was a significant trend toward decreased prostate cancer risk associated in those who reported a higher than average intake of legumes, nuts, both fin- and shellfish and vitamin E (alpha tocopherol).
Interestingly, milk was the only dairy product that was significantly associated with increased prostate cancer risk. Also, the study did not address the issue of grass vs. grain fed cattle, or the problem of pesticide or hormone contamination of milk. But whatever in milk was increasing the PC trend it was not mainly calcium (a theory floated in the past). Calcium showed only a borderline association with PC risk, with only a slightly higher risk with increased calcium consumption.
This study supports the theory that dairy products, and especially standard commercial milk, are involved in the causation of prostate cancer. However, the researchers caution that the mechanisms by which the various nutrients in dairy and in the total diet may interact to influence this risk remain unknown.
Raimondi S, Mabrouk JB, Shatenstein B, Maisonneuve P, Ghadirian P. Diet and prostate cancer risk with specific focus on dairy products and dietary calcium: a case-control study. Prostate. 2010;70(10):1054-1065.