According to the National Cancer Institute, prostate cancer affects one in every six men, and nearly 30,000 men die from prostate cancer each year in the United States. Numerous dietary factors have been studied for possible roles in the prevention of this disease, including dietary fat, lycopene, selenium, and omega-3 fatty acids. Flaxseed has gained considerable interest in recent years because it is a plant source of omega-3 fatty acids and is also rich in lignan, a phytoestrogen with antioxidant properties that has been shown to reduce testosterone levels.
A recent study conducted at seven research sites in the U.S. sought to investigate the role of ground flaxseed in prostate cancer proliferation rates (1). A total of 161 men with prostate cancer who were awaiting prostatectomy were randomly assigned to one of four treatment groups: 1) control group (continued their usual diet), 2) low-fat diet, 3) usual diet + flaxseed supplementation, and 4) low-fat diet + flaxseed supplementation. The men assigned to flaxseed supplementation consumed 30 grams of ground flaxseed (~3 rounded tablespoons) per day. When the study began, there were no differences between groups in prostate-specific antigen (PSA) or Gleason score, two measures of prostate cancer progression. Upon removal of the prostate, two researchers, both blinded to treatment assignments, independently evaluated cancer proliferation in the samples. The researchers found that regardless of dietary fat content, the groups receiving the flaxseed supplementation had significantly lower rates of cancer proliferation compared to those men who did not receive the flaxseed. This study is consistent with previous research suggesting that flaxseed has anti-cancer properties.
Denmark-Wahnefried W, Polascik TJ, George SL, Switzer BR, Madden JF, Ruffin IV MT, Snyder DC, Owzar K, Hars V, Albala DM, Walther PJ, Robertson CN, Moul JW, Dunn BK, Brenner D, Minasian L, Stella P, Vollmer RT. Flaxseed supplementation (not dietary fat restriction) reduced prostate cancer proliferation rates in men presurgery. Cancer Epidemiol Biomarkers Prev 2008;17(12):3577-87.