Data from a long-term study suggests a possible link between consumption of dairy products, including whole and skim milk, cheese and ice cream, and an increased risk of prostate cancer, researchers from Harvard School of Public Health said on April 4. Out of the 20,885 men tracked for 11 years in the Physicians' Health Study, 1,012 developed prostate cancer.
Based on dietary questionnaires, the investigators found a moderate elevation of risk of prostate cancer in men who consumed higher amounts of dairy products. The researchers believed that it could be the calcium in dairy products that is responsible for the higher cancer risk. Calcium can suppress levels of the most active form of vitamin D.
The study also found that men who drank more than six glasses of milk a week had lower levels of this potentially protective form of vitamin D than men who drank fewer than two glasses of milk a week. There has been speculation that calcium may play a role in the progression of a localized cancer into a metastatic, or spreading, disease.
The Physicians' Health Study found that a high consumption of dairy raised the risk factor for prostate cancer to about 1.3, or a 30% increase. By comparison, smoking raises a person's risk of contracting lung cancer by 15 to 30 times. The researchers noted that other studies, such as the Health Professionals Study of 1998, found a fairly strong prostate cancer risk elevation -- about 3 to 4 times -- in those taking calcium supplements.
Annual Meeting of the American Association for Cancer Research April 3, 2000 in San Francisco, CA
I am not surprised that milk has been found to be associated with another disease. However, I found it quite interesting that the researchers speculated that it was actually the calcium that may be contributing to the problem. I have not reviewed the actual study but it appears that the researchers are concerned that the calcium in non-physiologic levels may impair the function of the enzyme that converts vitamin D to its active form 1,25 Dihydroxyvitamin D.
This reaction occurs in the kidney and one can actually take a supplement of this active form of vitamin D, but it is a prescription (Rocaltrol) and is very expensive. Patients who have kidney failure need to take this supplement as their kidneys lose the ability to make this active form of vitamin D.
I find this observation a reassurance of my position that most of our supplements should be from food. When one attempts to force feed the body in what one "scientifically" determines to be valid, very delicate equilibriums can be upset and this can frequently lead to less than optimum health. JM
This study took place from 1984-1994. However, rBGH (Monsanto's bovine growth hormone) was not approved by the FDA until 1994. Therefore, this study only showed the effects of drinking non-rBGH milk. It is possible that rBGH milk could increase cancer risk even more, since the hormone has been shown to increase levels of IGF-1 in milk. CM