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Vitamins may reduce cancer risk in smokers

January 12, 2010

Leafy green vegetables and multivitamins could serve as protective factors against lung cancer in current and former smokers, according to a new study.

In the study, more than 1,100 current and former smokers submitted sputum samples and completed questionnaires regarding their dietary intake (1). The researchers analyzed cells in the sputum samples for the methylation status of genes that were linked to increased risk for lung cancer in previous studies. Aberrant gene methylation – the addition of a methyl (-CH3) group to DNA – is likely to be a major mechanism in lung cancer development and progression, as well as a potential marker for the early detection of lung cancer. The researchers next investigated associations between dietary variables and methylation.

The results showed that higher intakes of leafy green vegetables and multivitamin supplements rich in carotenoids (beta-carotene and lutein), vitamin C, vitamin B9 (folate), vitamin A and vitamin K were significantly associated with a reduced probability of high methylation, potentially associated with a reduced cancer risk.

The researchers said that in contrast to other findings suggesting that supplements containing beta-carotene conceivably increase the risk of lung cancer in heavy smokers when taken in extremely high doses over years, their results show that multivitamins may reduce cancer risk even in smokers.

Previous studies have suggested an association between a low vitamin B9 (folate) intake and increased lung cancer risk in current and former smokers. Higher folate intake has been associated with lower methylation of genes in colorectal tumors as well.

Additional research is needed to independently validate the current observations, and also to help resolve contradictions between varying studies, the authors concluded.

References

  1. Stidley C.A. et al. Multi-Vitamins, Folate, and Green Vegetables Protect Against Gene Promoter Methylation in the Aerodigestive Tract of Smokers. Cancer Research. 2010; 70(2):568–574.