Dairy Products Can Increase The Risk of Prostate Cancer
An overwhelming body of research suggests strongly that increased milk consumption is associated with increased risk for prostate cancer.
Over the past 50 years, a number of studies have been done examining the link between dairy products and prostate cancer.
In 1997, the World Cancer Research Fund and the American Institute for Cancer Research concluded that dairy products should be considered a possible contributor to prostate cancer.
Major studies suggesting a link between milk and prostate cancer have appeared in medical journals since the 1970s. Two of six cohort studies (research studies following groups of people over time) found increased risk with higher milk intakes. Five studies comparing prostate cancer patients to healthy individuals found a similar association. One of these, conducted in northern Italy, found that frequent dairy consumption could increase risk by two and one-half times.
In Harvard’s Physicians Health Study, including more than 20,000 male physicians, those who consumed more than two dairy servings daily had a 34% higher risk of developing prostate cancer than men who consumed little or no dairy products. Several other studies have shown much the same thing.
The evidence that pasteurized dairy products contribute to prostate cancer is fairly substantial. For instance:
- Worldwide, men seem far more likely to die of prostate cancer in countries where dairy consumption is high than in countries where it is low.
- In a 10-year study of nearly 21,000 male doctors, those who consumed at least 2.5 servings of dairy food per day were 30 percent more likely to develop prostate cancer than doctors who consumed less than half a serving.
The reasons why dairy contributes to prostate cancer are quite obvious
1. Most commercial milk brands contain synthetic growth hormones such as rBGH. And milk that contains rBGH also has especially high levels of Insulin-like growth factor-I (IGF-1).
IGF-1 acts as an important mediator between growth hormone and growth throughout fetal and childhood development. However. A study by Harvard researchers confirmed the link between IGF-1 levels in the blood and the risk of prostate cancer. Men who had an IGF-1 level between approximately 300 and 500ng/mL had more than four times the risk of developing prostate cancer than did men with a level between 100 and 185ng/ml.
2. Natural estrogens from cows (particularly from pregnant cows) in milk may be linked to breast, prostate, and testicular cancers in humans. All are “hormone-dependent” tumors, meaning that they need sex hormones to grow.
Natural estrogens are 100,000 times more potent than environmental estrogens and that today’s cow’s milk is particularly rich in them. The principal reason is that dairy farmers now milk their cows about 300 days per year. For much of that time the cows are pregnant, and as pregnancy progresses, the estrogen content of their milk increases. Milk from cows in the late stage of pregnancy can contain up to 33 times as much of the hormone estrogen as milk from non-pregnant cows.
While the average dairy cow produced almost 5,300 pounds of milk a year in 1950, today, a typical cow produces more than 18,000 pounds.
Calcium may also play a role in prostate cancer. Although the body needs some calcium, a high calcium load results in a lowering of blood levels of activated vitamin D. In the case of prostate cancer, where vitamin D is thought to be protective, high dairy intake could therefore have a harmful effect.
The Harvard School of Public Health has this to say: “A diet high in calcium has been implicated as a potential risk factor for prostate cancer. In a Harvard study of male health professionals, men who drank two or more glasses of milk a day were almost twice as likely to develop advanced prostate cancer as those who didn’t drink milk at all.”
How about organic milk?
Organic milk is better in many respects than conventional milk but still may be full of natural hormones. My advice: cut down on dairy products except low-fat ones. Substitute rice or almond milk for cow’s milk when possible.