Research Studies Vote ‘Soy Yes, Dairy No’

Controversy abounds on this topic; however, numerous studies over the past decade have shown a solid connection between the risk of prostate cancer and dairy consumption. A cohort study just published in mid 2005 by the American Journal of Nutrition showed that men with the highest dietary intake of dairy foods were 2.2 times more likely to develop prostate cancer than men with the lowest dietary intake of dairy foods.

Prior theories circled around the increase in IGF-1 (insulin growth hormone) seen in milk drinkers. High levels of IGF-1 have been directly linked to various hormonal cancers. Although this theory may still hold some validity, research has uncovered a potential cause that has further heated the debate on dairy and prostate cancer, calcium. The same study referenced above showed a 2.2 times increase in prostate cancer risk for men with the highest dietary calcium intake over those with the lowest. Another study in 2001 observed over 20,000 men, and concluded that men who consumed more than 600mg of daily calcium from dairy products had a 32% higher risk of prostate cancer than men who consumed less than 150mg of daily calcium from dairy products. This came as quite a shock, since the USDA recommends a minimum of 1200mg of daily calcium for men over 50, and 1000mg for men aged 19 to 50. These studies have spurred more medical research into this possible dairy calcium-prostate cancer connection.

Luckily, the news on prostate cancer isn’t all that bad. Several other nutrients, vitamins, and minerals have been given a gold star for their potential to reduce the risk of prostate cancer. Fructose (fruit), selenium (seafood, mushrooms, grains), vitamin D (sunshine), vitamin E (nuts, seeds, & greens), lycopene (tomatoes), soy…wait a minute…did we just mention soy in a discussion of men’s health? Oh yes, it seems that a prospective study in the US indicated a 70% reduction in the risk of prostate cancer among men who consumed more than one serving of soy milk per day.

As long as the medical community remains uncertain, there will be no shortage of clinical trials and interpretations addressing the subject of diet and prostate cancer. Below is a list of our resource articles and publications on this subject for more in depth reading:

World News

• “Harvard Researchers Link Prostate Cancer and Dietary Calcium” - CNN
• Vegan Diet 'Cuts Prostate Cancer Risk' - BBC News

Study Interpretation

• Flaxseed Shows Promise in Cancer Treatment
• Nutrition Action Health Newsletter – Preventing Prostate Cancer
• Casein Free for Cancer Prevention

Medical Publication

• American Journal of Clinical Nutrition – “Dairy, calcium, and vitamin D intakes and prostate cancer risk in the National Health and Nutrition Examination Epidemiologic Follow-up Study cohort”
• The Adventist Health Study - “Does high soy milk intake reduce prostate cancer incidence?”
• American Journal of Clinical Nutrition - “Dairy products, calcium, and prostate cancer risk in the Physicians' Health Study”
• National Library of Medicine – “Long-term dietary habits affect soy isoflavone metabolism and accumulation in prostatic fluid in caucasian men”

Educational Review

• Harvard School of Public Health – “Calcium & Milk”