Vitamin B6 and B12: Overkill

Clinical Brief – August 30th

The Brief

A new study published last week found that taking excessive amounts of vitamins B6 and B12 is linked to significantly elevated risk of lung cancer in men.

It doesn’t mean B6 and B12 causes cancer, but the data showed signs that men who intentionally seek B6 and B12 supplementation may be at increased risk of lung cancer.


What’s the study?

Between 2000 and 2002, a NCI-funded study asked ~77k Americans between the ages of 50 and 76 about the vitamins they took.

They then followed participants for an average of 6 years to count the number of lung cancers and compared those who had cancers with those who didn’t.

Now, vitamin B6 and B12 are important for the body to work properly. For instance, B6 is important for protein metabolism and B12 is important for making DNA.

For men of such age, the NIH recommends a daily intake of 1.7 mg of vitamin B6 and 2.4 mcg of vitamin B12.


What happens if we take 10-times that amount?

Men who took more than 20 mg of vitamin B6 or 55 mcg of vitamin B12 a day had nearly doubled risk for lung cancer than men who didn’t take supplements.

For smokers, those who took such high doses of B6 and B12 had nearly tripled lung cancer risk vs men who didn’t take supplements.

Curiously, women who took such amounts didn’t have increased risk of lung cancer. When the cancer risk is plotted by the dosage of B6 and B12 supplementation, there wasn’t a significant trend that said higher doses were tied to higher risks.

Of course, this isn’t the only problem with taking that much B6 and B12. The NIH actually lists side effects for taking too much B6 and B12.


Do B6 and B12 cause lung cancer?

Lung cancer isn’t gender-specific, so it’s hard to say vitamin B6 and B12 causes lung cancer. We can also say the same thing about how higher doses didn’t link to higher cancer risks.

But the results stand: Men who took way too much vitamin B6 and B12 did have significantly elevated risk of lung cancer. Why?

B6 and B12 are often included in supplements marketed to promote energy or help with stress. I’ll park their questionable medical claims aside, but could stress play a role?

Not all large studies focus specifically on people between 50-76. But in one study of people around 64 years old, men who had lung cancer were more likely to have had a “major stressful life event” in the past 5 years vs men who didn’t have cancer.


Bottom line

B6 and B12 may or may not cause lung cancer. But if you know any men over 50 who are reaching for that energy drink or that vitamin bottle way too much, it might be good to tell them about some of the signs and symptoms of lung cancer to watch out for.

One thought on “Vitamin B6 and B12: Overkill

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