Omega-3s alone, B vitamins (folate, vitamins B6, and B12) alone, or a combination of all these nutrients had no effect on the risk of various types of cancer, compared with placebo, according to findings published in the Archives of Internal Medicine.
The study used relatively low doses of the nutrients over a five year period in people with prior cardiovascular disease
“These ancillary results from the SU.FOL.OM3 trial do not provide evidence of beneficial effects of supplementation with B vitamins and/or ω-3 fatty acids in relatively low doses for five years on cancer incidence or mortality among CVD [cardiovascular disease] survivors,” wrote the researchers, led by Valentina Andreeva, PhD, from the University of Paris XIII.
Both B vitamins and omega-3 have been reported in the scientific literature to potentially prevent the development of cancer, via different mechanisms.
However, Dr Andreeva and her co-workers note that the evidence is “insufficient and inconclusive”, and sought to add to the evidence base by assessing cancer risk among the participants of the Supplementation With Folate, Vitamins B6 and B12 and/or Omega-3 Fatty Acids (SU.FOL.OM3) randomized clinical trial.
SU.FOL.OM3 involved 2,501 people aged between 45 and 80 with a history of cardiovascular problems (heart attack, unstable angina or ischemic stroke). The participants were randomized to receive 0.56 mg of 5-methyltetrahydrofolate plus 3 mg of pyridoxine hydrochloride (vitamin B6) and 0.02 mg of cyanocobalamin (vitamin B12), or 600 mg of the omega-3s eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), or a combination of all these nutrients, or placebo for five years.
Results indicated that 174 participants developed cancer during the trial, and there was no association between cancer outcomes and supplementation with B vitamins, omega-3 fatty acids or both.
“This study does not support dietary use of B vitamins or omega-3fatty acids for cancer prevention. The preliminary evidence of adverse effects among women necessitates confirmation before firm conclusions could be drawn,” concluded the researchers.
Source: Archives of Internal Medicine
Published online ahead of print, doi:10.1001/archintermed.2011.1450
“B Vitamin and/or -3 Fatty Acid Supplementation and Cancer: Ancillary Findings From the Supplementation With Folate, Vitamins B6 and B12, and/or Omega-3 Fatty Acids (SU.FOL.OM3) Randomized Trial”
Authors: V.A. Andreeva, M. Touvier, E. Kesse-Guyot, C. Julia, P. Galan, S. Hercber