Research published in the Archives of Internal Medicine found no beneficial effects of supplementation with relatively low doses of B vitamins and/or omega 3 fatty acids on cancer outcomes in individuals with prior cardiovascular disease.

The aim of the study was to advance knowledge about the cancer-chemopreventive potential of individual nutrients, including B vitamins and/or omega 3 fatty acids, among survivors of cardiovascular disease.

This was an ancillary study of the Supplementation With Folate, Vitamins B6 and B12 and/or Omega-3 Fatty Acids (SU.FOL.OM3) secondary prevention trial (2003-2009). In all, 2501 individuals aged 45 to 80 years were randomized in a 2 x 2 factorial design to one of the following 4 daily supplementation groups: 1) 5-methyltetrahydrofolate (0.56 mg), pyridoxine hydrochloride (vitamin B6; 3 mg) and cyanocobalamin (vitamin B12; 0.02 mg); 2) eicosapentaenoic and docosahexaenoic acid (600 mg) in a 2:1 ratio; 3) B vitamins and omega 3 fatty acids; or 4) placebo. Overall and sex-specific hazard ratios (HRs) and 95% CIs regarding the cancer outcomes were estimated with Cox proportional hazards models.

After 5 years of supplementation, incident cancer was validated in 7% of the sample (145 events in men and 29 in women), and death from cancer occurred in 2.3% of the sample. There was no association between cancer outcomes and supplementation with B vitamins and/or omega 3 fatty acids. There was a statistically significant interaction of treatment by sex, with no effect of treatment on cancer risk among men and increased cancer risk among women for omega 3 fatty acid supplementation.