Vitamin supplements do not protect against lung cancer, according to a U.S. study of more than 77,000 vitamin users. In fact, some supplements may even increase the risk of developing it.
"Our study of supplemental multivitamins, vitamin C, vitamin E and folate did not show any evidence for a decreased risk of lung cancer," said the study's author, Christopher G. Slatore of the University of Washington. "Indeed, increasing intake of supplemental vitamin E was associated with a slightly increased risk of lung cancer."
The findings were published in the first issue for March of the American Journal of Respiratory and Critical Care Medicine.
The research team selected 77,126 men and women between the age of 50 and 76, and determined their rate of developing lung cancer over four years with respect to their current and past vitamin usage, smoking, and other demographic and medical characteristics.
At the beginning, 521 developed lung cancer. Among these patients, in addition to the unsurprising associations with smoking history, family history, and age, there was a slight but significant association between use of supplemental vitamin E and lung cancer.
"In contrast to the often assumed benefits or at least lack of harm, supplemental vitamin E was associated with a small increased risk of lung cancer," said Dr. Slatore.
When modeled continuously, the increased risk was equivalent to a 7-percent rise for every 100 mg/day. "This risk translates into a 28-percent increased risk of lung cancer at a dose of 400 mg/day for 10 years," Dr. Slatore said. The increased risk was most prominent in current smokers.
The idea that vitamin supplements are healthy, or at the very least, do no harm, comes from the desire of many people to mimic the benefits of a healthy diet with a convenient pill, said Tim Byers from the University of Colorado School of Medicine in an editorial in the same issue of the journal.
However, he pointed out, "fruits contain not only vitamins but also many hundreds of other phytochemical compounds whose functions are not well understood."
(Xinhua/Agencies March 3, 2008)