Certain supplements may prove detrimental to women who've survived breast cancer, while older women may be at a slightly elevated risk from regular use of vitamin and mineral pills, medical investigators have found in two separate investigations.
In a study of 2,300 women, researchers at Columbia University in Manhattan found women treated for early stage breast cancer and who took vitamin A, lutein or beta-carotene, supplements known collectively as carotenoids, faced a greater risk of dying from recurrent cancer -- and virtually all other causes of death.
By contrast, those treated for early-stage breast cancer who routinely took vitamins C or E had a lower recurrence risk after five years than those who didn't take the vitamins. Vitamins C and E are known as antioxidants that protect cells.
"My main take home message here is that we're seeing antioxidant supplements working in one direction and the carotenoids working in another," said Dr. Heather Greenlee, who led the examination.
A second study in the Archives of Internal Medicine involving 38,000 women reported by researchers in Finland found U.S. women 75 and older who consumed any dietary supplements, including multivitamins, folic acid, iron and copper, had a 2.4 percent increased risk of death than those avoiding the pills. There was no risk associated with calcium and vitamin D.
Greenlee said it's unclear why vitamins C and E appeared to have a beneficial effect on cancer survivors -- if they did at all. It is possible, Greenlee said, that it wasn't vitamins C and E thwarting a recurrence, but other healthy behaviors the women shared that helped them avoid a second bout with cancer.
She said her research tried to help physicians guide breast cancer patients about vitamin use.
"We are not referring to vitamin A consumed in foods," Greenlee added. "Here, we are referring to supplements."
She noted that neither the American Cancer Society nor the American Institute of Cancer Research recommend vitamin supplements as a way to avoid cancer. A growing body of scientific evidence suggests supplements can be dangerous, Greenlee said.
Leah Pasquarella, chief clinical dietitian at Southside Hospital in Bay Shore, said the United States has evolved into a pill-popping culture where people think vitamins are beneficial without questioning how they affect the body. "I think we rely on them too much as a substitute for healthy foods and that's a problem," Pasquarella said.
Supplements, she added, are not regulated by the Food and Drug Administration, and potencies differ from one manufacturer to the next.
In Greenlee's research, findings were based on questionaires answered by women who had been diagnosed with early-stage breast cancer. More than 80 percent said they took at least one supplement containing antioxidants, either as a multivitamins or as single pill within two years of diagnosis.
Women who said they took a single supplement of either vitamin C or vitamin E six to seven days a week had a lower risk of cancer recurrence. Greenlee's analysis is reported in the current issue of the journal Cancer.