by ecancer reporter Janet Fricker

Giving patients with cardiovascular disease supplements of folate, vitamin B6, vitamin B 12 and/ or omega 3 fatty acids delivered no benefits for cancer prevention,  finds a  study published in Archives Intern Medicine.

Furthermore, the French randomised study showed that women, but not men taking omerga-3 fatty acids had an increased risk of developing cancer compared to controls. 

Previous studies have suggested that long chain polysaturated fatty acids of the 3 series might restrict tumour cell proliferation by increasing apoptosis. In the current study Valentina Andreeva and colleagues, from the Nutritional Epidemiology Research Centre at the University of Paris, randomised 2501 individuals aged between 45 and 80 years to one of four daily supplementation regimens:

 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.

4. Placebo

Results after five years of supplementation results revealed a statistically significant interaction of treatment by sex, with no effect of treatment on cancer risk among men but an increased cancer risk among women taking  omega 3 fatty acid supplementation (HR, 3.02 [95% CI, 1.33-6.89]).

“This study does not support dietary use of B vitamins or (omega 3) fatty acids for cancer prevention,” write the authors.  The preliminary evidence of adverse effects among women, they add, necessitates confirmation before firm conclusions can be drawn. 

The findings, they add, are consistent with a large epidemiological study in postmenopausal women which showed fish intakes to be positively associated with breast cancer risk.

Reference

VA Andreeva, M Touvier, E Kesse-Guyot, et al.  B vitamin and/or Omega-3 Fatty Acid Supplementation and Cancer. Arch Intern Med. Published online February 13, 2012.  doi:10.1001/archinternmed.2011.1450