Higher levels of vitamin B6 and a common amino acid called methionine may reduce your risk of lung cancer, the worlds most common cause of cancer death- whether or not youve ever smoked. A study involving nearly 400,000 participants in the European Prospective Investigation into Cancer and Nutrition (EPIC) reports that higher blood levels of vitamin B6 and methionine, found in most proteins as well as nuts and seeds, were associated with reduced rates of lung cancer regardless of smoking status.Previous research has suggested that deficiencies in B vitamins may increase the probability of DNA damage, leading to instability in the bodys genetic blueprint. EPIC researchers Paul Brennan, PhD, of the International Agency for Research on Cancer in France, and colleagues noted, Given their involvement in maintaining DNA integrity and gene expression, these nutrients have a potentially important role in inhibiting cancer development, and offer the possibility of modifying cancer risk through dietary changes.Brennan and colleagues analyzed data on 385,747 EPIC participants who provided blood samples, among whom 899 were diagnosed with lung cancer an average of five years later. The cancer patients blood levels of B vitamins and methionine were compared to 1,770 cancer-free control participants who were individually matched by country, sex, date of birth and date of blood collection.
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After adjusting for smoking and other factors, researchers found that people with the highest levels of vitamin B6 were 56% less likely to develop lung cancer than those with the lowest B6 levels. Similarly, those with the most methionine were at 48% lower risk of lung cancer. Having above-average levels of both vitamin B6 and methionine was associated with a 59% lower risk.Similar and consistent decreases in risk were observed in never, former and current smokers, indicating that results were not due to confounding by smoking, Brennan and colleagues wrote in the Journal of the American Medical Association (JAMA).Above-average levels of folate were linked to moderately lower risk, although only in former and current smokers. No significant trends were seen for blood levels of vitamin B2, vitamin B12 or homocysteine, another amino acid.Brennan and colleagues added, It is essential that for lung cancer prevention, any additional evidence about causality does not detract from the importance of reducing the numbers of individuals who smoke tobacco.TO LEARN MORE: JAMA, June 16, 2010; abstract at jama.ama-assn.org/cgi/content/ short/303/23/2377