Higher blood levels of vitamin B6 associated with lower risk of lung cancer

People with higher blood levels of vitamin B6 and the amino acid methionine appear to have a lower risk of lung cancer, a French study has found. But more research is needed to understand if higher levels of the nutrients directly protect against the disease.

Scientists at the International Agency for Research on Cancer in Lyon studied blood samples from 2,669 people from ten countries across Europe. Nearly 400,000 people had originally donated blood samples, and 899 people out of this group had been diagnosed with lung cancer by 2006.

Samples from the participants who had later been diagnosed with lung cancer were then compared with samples from 1,770 cancer-free participants who were from the same countries, had donated blood at the same time, and were the same age and sex.

Researchers discovered that people with higher levels of vitamin B6 in their blood had a lower risk of lung cancer, as did people with higher levels of methionine, which is found in most sources of protein.

Previous research has suggested that B vitamin deficiencies may increase the chances of DNA damage, which can lead to cancer. These deficiencies are known to be common in many western populations, and the researchers suggested that these nutrients "may have a potentially important role in inhibiting cancer development". But they also cautioned that their findings do not prove that boosting levels of these nutrients in the diet could reduce the risk of lung cancer.

The study, published in the Journal of the American Medical Association, showed that the association between high vitamin B6 levels and lower lung cancer risk was also found in people who were smokers or had previously smoked.

Overall, the researchers found that people who had higher levels of both vitamin B6 and methionine were at least 50 per cent less likely to develop lung cancer than those with lower levels of the nutrients. They also found that people with higher levels of folate, vitamin B6 and methionine were two-thirds less likely to develop lung cancer.

Dr Joanna Owens, science information manager at Cancer Research UK, commented: "Although this study suggests a link between vitamin B levels in the blood and reduced risk of lung cancer, this doesn't prove that vitamin B can directly protect against the disease. Vitamin B levels might be higher in people who eat a healthy diet, and this in itself can help reduce the risk of cancer.

"The most important way to prevent lung cancer is to stop smoking. No amount of vitamins can counteract the risks posed by smoking."