A study of more than 75,000 adults found that taking supplemental multivitamins, vitamin C and E and folate do not decrease the risk of lung cancer.
The findings are being reported at the American Thoracic Society 2007 International Conference.
The study, which also did not find any increased lung cancer risk from the supplements, is one of the most detailed, prospective observational studies to look at the effect of vitamin supplements instead of vitamins from foods on lung cancer risk.
"People are spending billions of dollars on supplements, and there is a general sense in the population that they prevent cancer," said researcher Chris Slatore, M.D., of the University of Washington School of Medicine in Seattle."We need to find out if they're helpful or even harmful."
The 77,738 men and women in the VITamins And Lifestyle (VITAL) study, ages 50-76, filled out an extensive questionnaire on vitamin intake over the previous 10 years, including how much of each supplement they took. The researchers then checked to see how many of the people in the study had lung cancer, using a government cancer registry. They found 393 cases of lung cancer. Adjusting for such risk factors as smoking, age, sex, cancer history, other lung disease and history of lung cancer, they found no statistically significant relationships between different types of supplements and lung cancer.
In 1996, a large study known as the CARET study which was looking into the effects of the dietary supplements beta-carotene and retinol (vitamin A), was halted after the supplements were found to increase lung cancer risk, particularly among smokers. That study, and others, encouraged researchers to look more deeply into the relationship between supplements and lung cancer, Dr. Slatore said.
The new lung cancer and supplements study is part of a larger study that is looking at supplements and various types of cancer, including prostate cancer and breast cancer, Dr. Slatore said.
Supplements have been getting a lot of attention this year. In February, the Journal of the American Medical Association published an overview of studies that found that supplements of beta-carotene, vitamin E, or vitamin A slightly increases a person's risk of death.