Men who take high doses of Grape Seed Extract over a longer period are 62 percent less likely to develop prostate cancer than men who don't take the supplement. Researchers at the University of Washington discovered this when they tracked 35,000 men aged between 50 and 76 over a period of six years.
The study, the results of which were published in Nutrition and Cancer, is part of the Vital Study, an epidemiological research project to study the positive effects of long-term supplement use. This particular part of the project focused on prostate cancer.
The researchers looked at the use of supplements that would be expected to reduce the chance of prostate cancer, such as Grape Seed Extract, chondroitin, Q10, fish oil, garlic, Ginkgo biloba, ginseng, glucosamine and of course saw palmetto.
Of all these supplements, Grape Seed Extract was the only one that reduced the likelihood of prostate cancer by a statistically significant amount. Users had 41 percent less chance of developing prostate cancer than non-users. Among the long-term users who took higher doses the effect was even stronger.
Numbers 2 and 3 in the Anti-Prostate Cancer Top Ten are fish oil and ginseng, but neither performed well in this study.
Grape Seed Extract contains phenols: flavones, phenolic acids and resveratrol. In experiments with prostate cancer cells, Grape Seed Extract and its components inhibit the transcription factor nuclear factor kappa-B, the inflammatory protein interleukine-6 and the biosynthesis of inflammatory factors produced by cyclooxygenase enzymes, thereby blocking the growth of prostate cancer cells.
This is the first study directed specifically at supplements' ability to protect against prostate cancer. Because not much is known, the researchers are cautious. "Any public health recommendation for grapeseed would require replication of our findings in humans as well as further clarification of mechanisms of action."
Nutr Cancer. 2011 May;63(4):573-82.