We tested the hypothesis that low-dose supplementation of omega-3 fatty acids reduces serum total testosterone levels. For the present substudy of the Alpha Omega Trial we included 1,850 male patients aged 60-80 who had blood samples available at baseline and after 40 months of follow-up. Additonal amounts of 400 mg/day EPA-DHA and/or 2 g/day ALA did not affect serum total testosterone levels. Moreover, omega-3 fatty acid supplementation did also not affect the risk of incident testerone deficiency.


Androgens including testosterone may play a role in prostate cancer developement and progression. There is inconclusive evidence that EPA-DHA may protect against prostate cancer and that ALA has a possible detrimental effect. Our results do not support the hypothesis that ALA increases and EPA-DHA decreases testosterone levels, and thereby affect the risk of prostate cancer.