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 investigated links between national diets and prostate cancer mortality rates to identify major risk factors. Prostate cancer mortality rates in the US 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 plant products including cereals/grains, beans, fruits and vegetables. 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 (garlic, leeks and onions) as important risk reduction factors for prostate cancer. This study also found that alcohol is a minor risk factor.

These results are similar to results reported 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.

These results should provide guidance for reducing the risk of prostate and other cancers.

Grant & Associates Health Research, Dec 22, 2003