Do B Vitamins Cause Lung Cancer In Men?
Author: Dr. Stephen Chaney
Last week one of my readers contacted me and asked me to comment on an article in The Atlantic titled: “Vitamin B6 and B12 Supplements Appear to Cause Cancer in Men”. I did what any good scientist would do. I read the original study (T.M. Brasky et al, Journal of Clinical Oncology, 35: 3440-3448, 2017 ) and analyzed the data, so I could provide you with the truth behind the headlines. Continue reading to find the answer to “Do B vitamins cause lung cancer in men?”
I will give you my analysis in a minute. First, let me use the internet chatter about this study as a perfect example of how nutrition myths are born.
How Did Journalists Interpret The Clinical Study?
Journalists are not trained scientists. They seldom read the whole article. They rely on the abstract of the article and interpret it through their “filter” of reality. The author of The Atlantic article did a reasonably good job of reporting the information in the abstract. However, news articles need to be spectacular to attract readers, so the information was presented selectively.
The author was clearly trying to grab your attention by hyping the risk. For example, in page one of his article, he makes the claim that “taking vitamin B6 and B12 supplements in high doses (like those sold in many stores) appears to triple or almost quadruple some people’s risk of lung cancer.” That is enough to get your attention!
If you read to page 4 of his article, you discover that the 3-4-fold increase in risk only applies to smokers. If you read to page 5, you discover that this only applies to people taking 20 times the RDA of B6 or B12 from individual supplements.
However, in today’s world many readers have the attention span of gnats. They will read the headline and perhaps the first couple of paragraphs. Most readers of The Atlantic article will conclude that supplementation with B6 and B12 causes a 3-4-fold increase in lung cancer in men. A nutrition myth will be born!
The headlines were similar from other news sources: CNN led with “High Doses of Vitamin B Supplements Tied to Lung Cancer, Study Says”. Huffington Post said: “Men: Taking Vitamin B6 and B12 Could Increase Your Risk of Lung Cancer.” USA Today said: “Risk of Lung Cancer Increases with Vitamin B, Study Says.”
In all fairness, the articles themselves offered a more balanced interpretation of the study, but many people do not read beyond the headlines. The headlines alerted people to the potential of B6 and B12 supplementation to increase the risk of lung cancer, but readers may miss the fact that this risk is only seen in men, only associated with mega-doses of individual vitamins, and only seen in smokers.
How Will Bloggers Interpret The Clinical Study?
It is only a matter of time before the same headlines start appearing in your favorite nutrition blogs. Many bloggers like to create sensational headlines and hype the results of clinical studies. They don’t let the facts get in the way of a good story. Of course, once the claim that vitamins B6 and B12 increase the risk of lung cancer gets repeated often enough on the internet, people will start to believe it must be true. The food myth will become firmly established.
How Will The Medical Community Interpret The Clinical Study?
The medical community usually filters studies like this through a belief system that supplements do more harm than good. They tend to ignore dozens of studies showing the benefits of supplementation and focus on the one of two suggesting they might cause harm. I predict that doctors may start advising their male patients to avoid supplements with vitamins B6 and B12. I also suspect many doctors may start measuring your blood levels of B6 and B12 and warning you to cut back if they are above average.
How Does A Scientist Interpret The Clinical Study?
Do B vitamins cause lung cancer in men? For a scientifically accurate evaluation of a study like this, one needs to read the study carefully, analyze the data, and evaluate the statistics. Let me walk you through stepwise what I found when I did that.
- The increased lung cancer risk was only seen in men, not in women. That would be the expected result for prostate cancer, but it is a bit unexpected for lung cancer. There is no apparent mechanism for explaining this effect.
- There was no effect of folic acid on lung cancer risk.
- Vitamins B6 and B12 were associated with a 30-40% increased risk of lung cancer in men. However, that statistic is misleading because:
- The increased risk of lung cancer was only seen when B6 or B12 were taken as individual supplements. There was no increased risk when B6 and B12 were in a multivitamin where all the B vitamins are in balance.
- The increased risk of lung cancer was only seen when B6 or B12 were taken as mega-doses greater than 20 times the RDA. There was no increased risk of lung cancer for doses of B6 or B12 that were less than 20 times the RDA.
- Mega-doses (>20 times the RDA) of vitamins B6 or B12 were associated with a 2-fold increased risk of lung cancer in men. However, that statistic is misleading because:
- The increased risk of lung cancer in men taking mega-doses of B6 or B12 was only seen in smokers. In the words of the authors: “There were too few [lung cancer] patients among never smokers to evaluate associations [between B vitamins and lung cancer].”
Do B Vitamins Cause Lung Cancer In Men?
Much of what you read on the internet about this study is misleading. For example:
- The claim that vitamins B6 and B12 increase lung cancer in men by 30% was entirely driven by men who were taking >20 times the RDA of B6 or B12 as individual supplements. The risk was zero for anyone taking lower doses B6 and B12.
- The claim that mega-doses of B6 or B12 increase lung cancer risk in men by 2-fold was entirely driven by male smokers. The risk was zero for non-smokers, even non-smokers taking mega-doses of B6 or B12.
- The only unambiguous conclusion from this study is that male smokers who take >20 times the RDA of either B6 or B12 as individual supplements have a 3-4-fold increased risk of lung cancer.
So, do B vitamins cause lung cancer in men?
What Does This Mean For You?
The take home lessons from this study are clear.
- It is almost never a good idea to take mega-doses of individual vitamin and mineral supplements. The only exception is when they are prescribed for a specific medical condition by your health professional and that health professional is monitoring you for potential toxicity.
- If you smoke, mega-doses of vitamins won’t protect you, and they may harm you. The best advice is to stop smoking.
Those are the scientifically based recommendations from the study. However, you are more likely to hear recommendations that you shouldn’t take B vitamins if you are a man. After all, nutrition myths don’t need to be based on science.
The Bottom Line
The internet is ablaze with claims that a recent study shows the vitamins B6 and B12 increase the risk of lung cancer in men. These claims are misleading because:
- The claim that vitamins B6 and B12 increase lung cancer in men by 30% was entirely driven by men who were taking >20 times the RDA of B6 or B12 as individual supplements. The risk was zero for anyone taking lower doses B6 and B12.
- The claim that mega-doses of B6 or B12 increase lung cancer risk in men by 2-fold was entirely driven by male smokers. The risk was zero for non-smokers, even non-smokers taking mega-doses of B6 or B12.
- The only unambiguous conclusion from this study is that male smokers who take >20 times the RDA of either B6 or B12 as individual supplements have a 3-4-fold increased risk of lung cancer.
The take home lessons from this study are clear.
- It is almost never a good idea to take mega-doses of individual vitamin and mineral supplements. The only exception is when they are prescribed for a specific medical condition by your health professional and that health professional is monitoring you for potential toxicity.
- If you smoke, mega-doses of vitamins won’t protect you, and they may harm you. The best advice is to stop smoking.
Those are the scientifically based recommendations from the study. However, you are more likely to hear recommendations that you shouldn’t take B vitamins if you are a man. After all, nutrition myths don’t need to be based on science
These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.