Newswise — A new multi-country study strengthens the link between animal products as risk factors for prostate cancer, and vegetable products, especially onions, as risk reduction factors. The study, now on line at European Urology,* (William B. Grant, Ph.D., A multicountry ecologic study of risk and risk reduction factors for prostate cancer mortality, European Urology, doi:10.1016/j.eururo.2003.08.018), investigated links between national diets and prostate cancer mortality rates to identify major risk factors for prostate cancer. The indication that this might be a useful approach comes from comparing national prostate cancer mortality rates: prostate cancer mortality rates in the U.S. and northern Europe are approximately 5 times higher than in Hong Kong, Iran, Japan, and Turkey.
The strongest risk factor for prostate cancer mortality was animal products, such as meat and dairy products; the strongest risk reduction factors were onions and other protective vegetable products (cereals/grains, beans, fruits, and vegetables, but excluding alcohol, oils, and added sugar (sweeteners)). Thus, fat and protein are risk factors, while complex carbohydrates and antioxidants are risk reduction factors. This finding points to insulin-like growth factor-I (IGF-I) being an important risk factor for prostate cancer. IGF-I is also increased by total energy consumption. This study supports earlier reports that allium family vegetables (e.g., garlic, leeks, and onions) as important risk reduction factors for prostate cancer. This study also found that alcohol is a minor risk factor. No independent correlation was found for tomatoes, a source of lycopene, thought to reduce the risk of prostate cancer.
Prostate cancer mortality rates for 32 predominantly Caucasian countries for the late 1990s were obtained from the World Health Organization. Dietary supply data were obtained from the Food and Agriculture Organization. Linear and multiple linear regression analyses were conducted for all 32 countries as well as the 20 European countries. Dietary supply data for 1979-81 yielded the highest correlations, indicating that prostate cancer takes approximately 20 years to progress from initiation to death.
These results are similar to results reported by Dr. Grant last year for breast cancer, although onions were not found to play a role for breast cancer. Animal products including animal fat and alcohol are now recognized risk factors for breast cancer, and vitamin D is recognized as an important risk reduction factor. UVB radiation, the primary source of vitamin D for many people, was inversely correlated with prostate cancer mortality rates but not in a multiple linear regression with the dietary factors.
These results should provide guidance for reducing the risk of prostate and other cancers.
William B. Grant does independent health research from his office in Newport News, Virginia. His health work is primarily related to identifying and quantifying links to chronic diseases from dietary factors and solar UV-B. He published the first paper linking diet to Alzheimer's disease in 1997.
*European Urology URL:http://www.sciencedirect.com/science?_ob=JournalURL&_cdi=7228&_auth=y&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=eb6396c384afe118940ab6b4e9467d94 (hit "Articles in Press")
*Grant WB. An ecologic study of dietary and solar UV-B links to breast carcinoma mortality rates. Cancer, 94, 272-281, Jan. 1, 2002.http://www3.interscience.wiley.com/cgi-bin/abstract/89012143/START
*Grant WB. An estimate of premature cancer mortality in the United States due to inadequate doses of solar ultraviolet-B radiation, Cancer, 94(6), 1867-75, March 16, 2002. http://www3.interscience.wiley.com/cgi-bin/abstract/91016211/START
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