You’ve probably seen the scary headlines claiming that taking vitamins might kill people or raise risk for cancer. Should we toss out our supplements and worry that the ones we’ve already taken may boomerang against us? A lot depends on the quality of the science, as two new studies of the risks and benefits of vitamins show.
In the first study, published in October in Archives of Internal Medicine, researchers linked multivitamins, vitamin B6, folic acid, iron, magnesium, zinc and copper to a slightly increased risk of death in older women over an average of 19 years. In another study, taking vitamin E supplements raised the risk of prostate cancer by 17 percent among the 35,000 men participating (the expectation was that risk would drop among men taking the supplement). That all sounds alarming, so how worried should we be? Here’s a look behind the headlines, along with the scoop on which supplements might be helpful and which ones you may want to avoid.
Do Vitamins Kill Women?
In the long-running Iowa Women’s Health study, about 38,000 older women (average age at the start of the study 61.6) answered 127 questions on a 16-page questionnaire about eating habits and use of supplements in 1986, 1997 and 2004. When the researchers tracked the women’s health for 18 years, they found a 2.4 percent rise in mortality for women who took multivitamins, and a 3 to 6 percent rise for women who took vitamin B6, folic acid, iron, magnesium and zinc. This type of study is “observational.” That means it isn’t designed to prove cause and effect, but rather to identify patterns that might provide insights.
Why You Should Be Skeptical
Critics contend that relying solely on the women’s recollections about which supplements they had taken in the past wasn’t all that scientific, since memory can be faulty. Also, women who took vitamins were nearly twice as likely to have also used estrogen replacement therapy after menopause, a factor that could have skewed the results, given the health problems that have been linked to hormone drugs. The researchers didn’t look whether the women had taken other prescription drugs that could have affected their health. In summing up the findings, the researchers acknowledged that most supplements were “unrelated to total mortality rate”.
Best and Worst Supplements
The good news from the supplement study is that calcium, the bone-building mineral, got a clean bill of health. Better yet, it was linked to a reduced risk of death in older women, who often take calcium plus vitamin D to reduce risk for osteoporosis, the brittle bone disease that can lead to potentially fatal fractures. The researchers reported the highest rise in death rates (18 percent) among women who took copper supplements, and also warned that progressively smaller doses of iron were linked to increased mortality rates in women as they aged.. “The only reason to take an iron supplement is if a blood test has revealed iron deficiency anemia, and you are advised to take it by your physician,” integrative medicine pioneer Andrew Weil, MDreports on his website.
Does Vitamin E Give Men Prostate Cancer?
The study that found a higher risk of prostate cancer in men who took 400 IU of vitamin E daily was a double-blind, randomly controlled trial in which neither the participants nor the researchers know who is getting the supplement and who is getting the placebo. This type of study is deemed the gold standard of scientific research. More than 35,000 men took part at 400 locations in the United States, Canada and Puerto Rico. The trial compared vitamin E, the mineral selenium, and a combination of both, with a placebo. Results from each arm of the trial were compared to each other and to the control (placebo) group.
Why Men Should Take This Study Seriously
The trial was stopped early, in 2008, after an analysis found no benefit to taking vitamin E, and a possibility of an increased risk of prostate cancer and diabetes. Follow-up data published in Journal of the American Medical Association on October 12 showed a 17 percent increased risk of prostate cancer, but no additional threat of diabetes, in the vitamin E group. “For the typical man, there appears to be no benefit in taking vitamin E, and in fact, there may be some harm,” said Eric Klein, MD, the study coordinator, in a Cleveland Clinic news release.