No benefit of B vitamins or omega-3 on cancer outcomes, study finds

There are 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, according to a study published online February 13 in the Archives of Internal Medicine.

The supplementation with folate, vitamins B₆ and B₁₂, and/or omega-3 fatty acids study, conducted between 2003 and 2009 in France, randomized 2,501 individuals ages 45 to 80 years with prior myocardial infarction, unstable angina, or ischemic stroke during the previous year. Individuals were placed in 1 of 4 daily supplementation groups: 5-methyltetrahydrofolate (0.56 mg), pyridoxine hydrochloride (vitamin B₆, 3 mg), and cyanocobalamin (vitamin B₁₂, 0.02 mg); eicosapentaenoic and docosahexaenoic acid (600 mg) in a 2:1 ratio; B vitamins and omega-3 fatty acids; or placebo.

After 5 years, incident cancer was validated in 7% of the sample – 145 incident cancer events in 1,987 men and 29 in 514 women, 83% of who were menopausal. Death from cancer occurred in 2.3% of the sample.

Investigators found no association between cancer outcomes and supplementation with B vitamins (HR=1.15; 95% CI, 0.85-1.55) and/or omega-3 fatty acids (HR=1.17; 95% CI, 0.87-1.58).

There was no effect of treatment on cancer risk among men, but women had 3 times the risk when taking omega-3 fatty acids (HR=3.02; 95% CI, 1.33-6.89). Cancer events occurred in 7.0% of patients and death from cancer in 2.3%.

Investigators cautioned that the findings are preliminary and hypothesis generating for future studies.