Foods such as oily fish (especially salmon, sardines and tuna — the “fishier” the better), ground flaxseed or flaxseed powder, walnuts and canola oil have useful amounts of omega-3 fatty acids, which show protective benefits against prostate cancer development in most, but not all, of the relevant studies. Having some fish, walnuts or flaxseed (1 to 2 tablespoons) daily is reasonable.
Increased omega-3 fatty acids are associated with less heart disease as well. One small study using ground flaxseed and a low-fat diet in men with prostate cancer showed an improvement in tumor markers. Flaxseed oil is less likely to be beneficial because many of the valuable components have been removed.
