Diet has long been thought to be associated with the development of prostate cancer that is common in Western countries and rare in Japan and Asia. In a study published in October 2004 by the Urological Sciences Research Foundation found that when Japanese men migrate to the United States and adopt a Western lifestyle, the protection begins to disappear within one generation. The researchers suggested that the western diet containing high animal saturated fats and low soy content may be the contributors to the higher incidences of prostate cancer.
Soy and Prostate Cancer: decades of promising data
Many people often associate the benefits of soy with breast cancer. Indeed, data on soy and prostate cancer has been most promising; many studies support the role of soy in the prevention and possible treatment of prostate cancer. During the late 80s, researchers found that Japanese men in Hawaii who ate tofu at least 5 times per week had 65% less chance of developing prostate cancer than those who ate tofu only once a week or less. In 1998, researchers found that men who drank soy milk at least once a day had a 70% less chance of developing prostate cancer than those who never drank soy milk at all.
Soy has also been found to be potentially beneficial in treating prostate cancer and slowing its progression in many animal and in vitro studies. Lately, more human studies point to similar results. In a small study published in Urology in September 2004, Australian researchers found that men consuming a soy-enriched diet had a statistically significant drop of 12.7% in prostate-specific antigen (PSA) levels, compared to the control group whose PSA levels rose 40%.
Soy and Prostate Cancer - the bottom line
Study after study seems to show that diet is one of the major factors in relation with incidences of prostate cancer. Prostate cancer incidence and mortality rates in Asian countries are much lower than in the United States. Research suggests that one of the reasons for this difference in incident rates may be the high soy content in the Asian diet. In Asian countries, the estimated isoflavone mean daily intake is between 10-50 mg per day. The Louis Warschaw Prostate Cancer Center in California recommends an intake of 35 to 40 g of soy protein daily. However, it is still not clear whether the benefits are due to its soy protein, or its isoflavones daidzein and genistein, or the combination of them. The best approach is to include soy foods such as tofu, tempeh, soy milk, edamame etc in your diet instead of taking soy isolate supplements.
With increasing public concerns regarding genetically modified foods, look for soy products which use non-genetically modified soy crops in their production.
Information on this site is provided for informational purposes and is not meant to substitute for the advice provided by your own physician or dietitian. Information and statements have not been evaluated by the Food and Drug Administration and are not intended to diagnose, treat, cure, or prevent any disease.