Smoking causes lung cancer — no surprise there. But a new study found that high dosages of vitamin B6 or B12 supplements were associated with three to four times the lung cancer risk in male smokers compared with smokers who did not take the supplements. The results were published in the Aug. 22, 2017, Journal of Clinical Oncology.
Researchers examined information from more than 44,000 men ages 50 to 76. At enrollment, the men reported on their smoking history and their B vitamin supplement use over the previous 10 years. In the study, high intake of B vitamin was classified as 20 milligrams (mg) of B6 per day or 55 micrograms (mcg) of B12. (The recommended daily intakes for men ages 51 and older are 1.7 mg for B6 and 2.4 mcg for B12.)
B vitamins help strengthen the immune system, according to the researchers, so it is not clear why high levels of supplemental B vitamins would increase rather than decrease smokers' lung cancer risk. They speculated that the B vitamins might feed small, undetected tumors and make them grow faster.
B vitamins aside, not smoking remains the most important way to prevent lung cancer. In fact, the researchers also found that men who quit smoking for at least 10 years before the study and also took high dosages of the B vitamins did not have a higher risk of lung cancer. In fact, their risk was equal to that of men who had never smoked.
Although vitamin B supplements claim to increase energy and improve metabolism, a new study finds a relationship between high doses of certain B vitamins and an increased risk of lung cancer in male smokers.
Vitamin intake and cancer risk is a hot topic.
Lung cancer is the most commonly diagnosed cancer on a global basis (1.61 million Trusted Source diagnoses in 2008), as well as the most common cause of cancer-related death (with 1.38 million in the same year).
B vitamins – B-6, B-9 (folate), and B-12 – are commonly thought to reduce cancer risk, among other benefits. Worryingly, the exact opposite may be true if they are taken at high levels over long periods of time.
Over recent years, a number of studies have looked for links between lung cancer and B vitamins. To date, results have been inconclusive – this is partly because the trials were rarely randomized, they investigated only short periods of supplementation, and only small numbers of lung cancer cases were involved in the analysis.
However, one of the latest investigations found a 21 percent Trusted Source increase in overall cancer risk with supplementation of B-12 and B-9. This increase in risk was predominantly due to a rise in lung cancer risk. A Group of researchers from multiple institutions set out to probe this association in the most detailed study of its kind to date.
Scientists from the Arthur G. James Cancer Hospital and Richard J. So love Research Institute at the University Comprehensive Cancer Center in Columbus, OH, joined forces with the Fred Hutchinson Cancer Research Center in Seattle, WA, and National Taiwan University in Taipei.
Their combined work is the first prospective, observational study to examine links between long-term high doses of B-6 and B-12 supplements and lung cancer risk. The study was headed up by Theodore Brassy, Ph.D. – from the OSU CCC – and their results are published this week in the Journal of Clinical Oncology.
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