The study, published in Journal of Clinical Oncology, looked at a cohort of 77,000 adults, 800 of whom developed lung cancer during the study’s follow-up period of six years.
Although the team observed no increased risk among women taking B6 and B12 supplements, men who took more than 20 milligrams of B6 per day had an 82 percent greater chance of the disease, relative to those who didn’t.
Men who consumed more than 55 micrograms of B12 per day saw their risk of lung cancer increase by 98 percent relative to those who didn’t take B supplements.
What’s more, men who smoked at the outset of the study and consumed high levels of the B vitamins were three to four times more likely to develop lung cancer.
The study’s lead author, Theodore Braskey, noted: “High-dose B6 and B12 supplements should not be taken for lung cancer prevention, especially in men, and they may cause harm in male smokers.“B6 is typically sold in 100mg (milligram) tablets.
B12 is often sold between 500 mcg (microgram) and 3,000 mcg tablets.
“In contrast, most multivitamins include 100 percent of the U.S Recommended Dietary Allowance, which is under 2 mg per day for B6 and 2.4 mcg per day for B12.
“People should really ask if they need over 1,200 the recommended daily allowance of a substance”