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

Extract

Brasky et al. ( 1 ) report a correlation between the long-chain omega-3 fatty acid docosahexaenoic acid (DHA) in plasma phospholipids and prostate cancer. The difference in DHA levels between cancer and noncancer groups, although statistically significant, was small and of uncertain biological significance. Intakes of fish and fish oil supplements were not analyzed. Accordingly, the authors’ conclusion that prostate cancer risk should influence general advice to increase dietary omega-3 fatty acid intakes is not well supported by scientific evidence.

Brasky and colleagues used data from two case–control studies ( 1 , 2 ), which were nested within trials of interventions unrelated to eating fish or taking fish oil supplements. In these studies, the use of blood samples for analysis of plasma phospholipid DHA and other long-chain omega-3 fatty acids was incidental to the primary purpose of the studies. Neither study involved advice to eat fish or take fish oil supplements. In neither study were dietary intakes of fish or fish oils analyzed.