B Vitamins and Lung Cancer Risk

A recent study published recently in the Journal of the American Medical Association (JAMA) showed that people with higher blood levels of Vitamin B6, Folate (Vitamin B9), and the amino acid Methionine had a 67% lower odds-ratio of developing lung cancer compared to those with low levels of these nutrients.

According to the research team, the above odds ratio was largely the same among never smokers, former smokers and current smokers (meaning that in all three groups of smoking status, the odds ratio of developing lung cancer was about the same when comparing those who had high blood levels of these nutrients and those who had low levels). (Johansson M, et al. Serum B Vitamin Levels and Risk of Lung Cancer. JAMA. 010;303(23):2377-2385)

That said current smokers between the ages of 35 and 79 included in the research database analyzed by the study team had a much higher risk of lung cancer than either former smokers or never smokers. As a case in point, currently smoking men in the study with low levels of Vitamin B6 and Methionine had a 14.9% risk of developing lung cancer while currently smoking men with high levels of these two nutrients had only a 6.6% risk. On the other end of the spectrum, never smoking men in the study with low blood levels of Vitamin B6 and the amino acid Methionine had a 0.9% risk of developing lung cancer while those never smoking men with high levels of these two nutrients had a 0.3%.

To take a step back, the paper’s authors achieved their results by examining the medical records of over 500,000 Europeans who participate in a large, ongoing study (a generational study known as a cohort) called EPIC. They examined the EPIC database of patients to select those who had developed lung cancer after their initial blood draw (when their levels of B Vitamins and other nutrients were originally obtained). After eliminating some of the lung cancer patients for various confounding characteristics the researchers arrived at roughly 900 lung cancer patient records. They then selected approximately 1,800 control patient records from the database, attempting to find 2 cancer-free control patients of similar health/demographic characteristics for each of the lung cancer patients.

The researchers focused their study on B Vitamins and Methionine because, “B vitamins, including B6 and Folate (B9), as well as related enzymes in the 1-carbon pathway, are essential for DNA synthesis and methylation…Deficiencies in B vitamins may increase the probability of DNA damage and subsequent gene mutations, and may influence gene expression via aberrant methylation patterns. 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.”

In other words, these nutrients play a key role in healthy cell development and division. When low levels of these nutrients are present in the human body there is a greater likelihood of abnormal cell development and division (and abnormal cell development and division is at the root of cancer development).

For the paper’s authors, the puzzle arising out of the study results was the fact that there was less of a correlation between dietary intake levels of foods or nutritional supplements that contain these nutrients and lung cancer risk than there was with blood level amounts of the nutrients.

In other words, the study team did not find direct evidence to support the contention that consuming more foods and/or supplements with Vitamin B6, Folate and Methionine reduced lung cancer risk. Instead, the correlation discovered was based solely on blood levels of these nutrients.

But clearly, the main sources of these nutrients for humans are food and nutritional supplements that contain these ingredients. So if a person has higher blood levels of these nutrients it is logical to assume that they either consume more foods/supplements with these nutrients or their bodies better absorb the nutrients than people with low levels.

Despite the absence of proof that higher dietary intake of Vitamin B6, Folate and Methionine necessarily leads to higher blood levels of these nutrients, the study authors conclude, “Dietary sources of B6 are varied and include beans, grains, meats, poultry, fish, and some fruits and vegetables, whereas primary sources of methionine are from animal proteins, as well as some nuts and vegetable seeds.Given that serum levels of B vitamins and metabolites are at least partially determined by diet, and are clearly affected by vitamin supplements,low vitamin levels are therefore modifiable.” [Meaning, it seems to us, you can generate higher blood levels of these nutrients by consuming foods and supplements that contain them]

The study provided no guidance on specific dietary intake levels of Vitamin B6, Folate and Methionine. However, we have provided below links to fact sheets from the National Institutes Health’s Office of Dietary Supplements for Vitamin B6 and Folate that describe food sources and recommended daily dosage levels of dietary supplements for these nutrients. In addition, we’ve provided a link to a Wikipedia page with similar information for Methionine.

Vitamin B6
Folate
Methionine