The American Institute of Cancer Research (AICR) recommends avoiding supplements for cancer protection. Unfortunately, due to the fact that supplements are not regulated in the United States and that they have not been studied for long term use, many things remain questionable.
As a dietitian, I always encourage food first, as the naturally occurring form of vitamins is metabolized in context with other phytochemicals. Moreover, the chemical form of vitamins in food vs. supplements can be different. Of course, there is a time and a place for certain supplements if someone is deficient, or is at risk of a deficiency or for a therapeutic purpose. However, if and when possible, food sources are preferred.
Last week, there were several media reports stating that B vitamins are associated with an increased risk of lung cancer. After reading the journal article, I wanted to report back the facts.
- The study looked at characteristics of 77,118 participants over the course of ten years. People were ages 50 to 76 years old.
- They found that men who took the highest amounts of B6 and B12 from individual supplements were 30-40% more likely to develop lung cancer. The results were statistically significant and the association was stronger in people who presently smoked.
- Dietary intake of B vitamins was estimated through food frequency questionnaires.
As you take a deeper dive into the results, there were many aspects of the study that were not made obvious by media that are important to take into account:
- The entire population was from western Washington State
- The participants who were more likely to develop lung cancer “tended to be older, male and less educated at baseline....were more likely to be current cigarette smokers at baseline, have more pack-years of smoking, and had positive histories of chronic obstructive pulmonary disease and cancer”
- B vitamin supplemental use was higher among women than men but there was no associated found in women
- The authors make a note that “there were too few patients among never smokers to evaluate associations”
- Authors did not find any significant associations with dietary intake
- Can we generalize the findings from a specific region to other populations/is there something unique about the environment that could have contributed to the findings?
- Were the men in the study more likely to be exposed to other environmental factors increasing their risk that perhaps the women were not as likely to be exposed to? For example, what kind of work did the people do in the study/could they have been exposed to construction areas, etc.
- Does the form of B vitamins make a difference (methylated vs. not)?
- Should blood levels of B vitamins (dietary vs supplements) have been assessed via serum levels vs questionnaires to check for variation in absorption/ accuracy of reports?
- The fact that there were too few patients who were never smokers to draw any conclusions is misleading. When they say that the rate of lung cancer was higher in smokers who took B vitamins, are they comparing this population with former smokers as opposed to people who have never smoked?
My conclusion (but certainly read the original article and form your own!)
More studies need to be done and more populations need to be examined to see if there is an actual relationship between B vitamins and lung cancer.
In the meantime, unless you need to be taking supplemental B6 and B12, hold off and get it from foods, especially if you are male and a current or former smoker.
Foods high in B6 and B12:
- Fortified cereals
- Dark green vegetables
- Nutritional yeast
Brasky TM, White E & Chen C. Long term, supplemental, one-carbon-metabolism-related vitamin B use in relation to lung cancer risk in the vitamins and lifestyle cohort. 2017. J Clin Oncol. 35.