Do Regular Vitamin Supplements Increase the Risk of Lung Cancer?

Key Takeaways:

• Taking high doses of vitamins B6 and B12 may elevate the risk of lung cancer in men, especially for those who smoke, as per a recent study.
• The research did not aim to establish a direct cause-and-effect relationship between the vitamins and lung cancer, only an association. Further explanation as to why only men, particularly smokers, are at increased risk could not be clarified.
• It was revealed that most Americans get sufficient vitamins B6 and B12 from their diets, and some groups, like older individuals and vegetarians, might need supplements due to deficiencies.
• The study found that men consuming more than 20 milligrams of B6 and 55 micrograms of B12 daily over the past 10 years had a significant increase in lung cancer risk compared to men who did not take supplemental B vitamins.
• There are conflicting opinions among experts about the study’s findings, with some scientists believing in a protective effect of vitamin B6. Yet, it is clear that high dosage vitamin supplements may pose potential harm.

Taking high doses of vitamins B6 and B12 may elevate the risk of lung cancer in men, particularly in men who smoke, according to recent research. The study revealed nearly double the likelihood of developing lung cancer in men taking these vitamin supplements. For men who smoked, the risk increased three to four-fold.

The Study and Its Findings

The research did not aim to establish a cause-and-effect between the vitamins and lung cancer, but rather uncovered an association. Also, it could not clarify why only men and current male smokers seemed to face an increased risk. This study was conducted by Theodore Brasky, a Research Assistant Professor at Ohio State University. He stated, “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.”

Dietary Sources of Vitamin B6 and B12

Most Americans attain sufficient vitamins B6 and B12 through their diets, says the U.S. National Institutes of Health (NIH). Some groups, including older people and vegetarians, may require supplements due to deficiencies. On the other hand, certain health conditions may warrant supplements. Interactions with medications might also be caused by these vitamins. Enriched cereals and high-protein foods are dietary sources of vitamins B6 and B12.

Research Method and Result

This comprehensive study involved over 77,000 adults, aged 50 to 76, in Washington state. They were recruited between 2000-2002 and were asked about their vitamin intake over the past decade.

Out of the participants, just above 800 developed lung cancer over an average follow-up of six years. However, the study found no link between folate (a type of B vitamin) and lung cancer risk. Moreover, the risk didn’t seem to be affected by vitamin B6 and B12 supplements in women.

Increased Risk With Higher Dosage

Interestingly, the research found that men consuming more than 20 milligrams of B6 and 55 micrograms of B12 daily over the past 10 years had a significant increase in lung cancer risk compared to men who did not take supplemental B vitamins.

Brasky notes that regular multivitamins usually include 100 percent of the U.S. Recommended Dietary Allowance, which is under 2 mg for B6 and 2.4 mcg for B12 per day. He questioned the need for over 1,200 times the recommended allowance, adding that there is no scientific support for these extreme doses.

Conflicting Opinions

Paul Brennan, head of the genetics section with the International Agency for Research on Cancer, believes the study is valid, but conflicts with his team’s research, which did not find any link between higher blood levels of vitamin B6 and lung cancer. In fact, they found a slight protective effect, particularly in men. He further states that there is clearly no evidence that these vitamins bring substantial protective effects. “Smokers should quit smoking,” he advises.

Endorsing that advice, Dr. Eric Bernicker, a thoracic oncologist with Houston Methodist Hospital, said the research points to increased lung cancer risk from higher doses. He feels the general belief that vitamins could never harm is flawed.

In response, Duffy MacKay, a senior vice president of the Council for Responsible Nutrition, a trade group for the vitamin industry, urged consumers to avoid the temptation of sensational headlines from this study, altering their use of B vitamins. MacKay laden his statement with the underlying message of the numerous benefits of B vitamins and the limitations of the study.

The study was published in the Journal of Clinical Oncology.

Additional Resources

For more information about lung cancer, visit the American Cancer Society.