CHICAGO–Supplementing with low doses of B vitamins and/or omega-3 essential fatty acids (EFAs) did not prevent cancer for those who already suffer from cardiovascular disease (CVD) in a recent study from the Archives of Internal Medicine (DOI:10.1001/archintermed.2011.1450).
Valentina A. Andreeva, Ph.D., of the University of Paris XIII, and colleagues performed secondary analyses of data from the Supplementation with Folate, Vitamins B6 and B12 and /or Omega-3 Fatty Acids (SU.FOL.OM3) randomized controlled trial conducted in France from February 2003 to July 2009. Individuals between the ages of 45 to 80 who had an acute myocardial infarction (heart attack), unstable angina or ischemic stroke during the previous 12 months were eligible. In all, 2,501 patients (514 women and 1,987 men) were randomized in the trial.
Study participates followed one of the four supplement routines for the study:
- 5-methyltetrahydrofolate (folate, 0.56 mg), pyridoxine hydrochloride (vitamin B6; 3 mg) and cyanocobalamin (vitamin B12; 0.02 mg);
- eicosapentaenoic (EPA) and docosahexaenoic (DHA) fatty acids (600 mg)in a 2:1 ratio;
- B vitamins, DHA, EPA; or
- placebo.
After five years of supplementation, 7 percent of the sample (145 events in men and 29 in women) developed cancer, and death from cancer occurred in 2.3 percent of the sample. The researchers found no association between cancer outcomes and supplementation with B vitamins and/or omega-3 fatty acids.
Among women (about 83 percent of them were menopausal), both types of supplementation had a tendency to increase cancer risk, “however these results were derived from very few cases and should be regarded as preliminary," the researchers wrote.
They noted 83.3 percent of the cancer incidence and 81 percent of the cancer mortality occurred in men, who accounted for 79.4 percent of the sample, but neither type of supplementation produced any effects.
Harry Rice, vice president of regulatory and scientific affairs, Global Organization for EPA and DHA Omega-3s (GOED), said the study results don't evoke much emotion given that the primary objective of the SU.FOL.OM3 Study was to investigate whether dietary supplementation with B vitamins or omega 3 fatty acids, or both, could prevent major cardiovascular events in patients with a history of ischaemic heart disease or stroke. "The present publication includes analyses of data that was not included as part of the primary objective. Secondary objectives included prevention of death for any cause, including cancer. In essence, this was a fishing expedition and I would hope that the authors would acknowledge it as such." He said results from appropriate secondary analyses should be used to design future experiments, not draw conclusions.
Even given that, Rice said the most likely reason the long-chain omega-3s did not prevent major cardiovascular events in patients with pre-existing cardiovascular disease is the dose was too low in this study. "Consider that the American Heart Association (AHA) recommends 1 g/day of EPA and DHA for individuals with coronary heart disease," he said.
Further, he said no one study that is so well-designed and executed that would justify a change in eating or dietary supplement use. "It's about the totality of the available scientific evidence," he said. "While it's much too early to speculate about the anti-cancer benefits of the long-chain omega-3s, I can say I don't believe the present results support a cancer-promoting effect of the long-chain omega-3s. In addition, the cardiovascular benefits associated with the long-chain omega-3 fatty acids are well-documented, in healthy populations, as well as in the majority of populations with pre-existing cardiovascular ailments."
