RE: Plasma Phospholipid Fatty Acids and Prostate Cancer Risk in the SELECT Trial

Extract

Brasky et al. ( 1 ) reported that higher plasma omega-3 fatty acid levels were associated with increased risk for developing prostate cancer. The authors inappropriately implicated the dietary intake of omega-3 (fish and/or supplements) as potentially causal for prostate cancer, and they failed to consider other potential explanations for their observation. For example, He et al. ( 2 ) and Azordegan et al. ( 3 ) both provide evidence that in precancerous tissues early changes in fatty acid metabolism (eg, increases in the activity of delta-6-desaturase [D6D]) could increase tissue (and possibly plasma) levels of long-chain n-3 fatty acids. Hence, it is possible that metabolic changes (eg, upregulation of D5D and D6D, which produce long-chain from short-chain omega-3 fatty acids) associated with the carcinogenic process could have raised omega-3 levels. Second, higher levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are also observed in individuals with common polymorphisms in the FADS1 and FADS2 genes (that code for D5D and D6D, respectively). FADS1 polymorphisms have also been linked to increased risk for prostate cancer ( 4 ), and D6D inhibition can suppress tumor growth in mice ( 2 ). Because an increased intake of long-chain omega-3 fatty acids can suppress D6D by product inhibition ( 5 ), dietary or supplemental EPA and DHA could potentially reduce the risk of prostate cancer, as others have described.