Before you reach for your morning vitamins, consider this: They may not be good for you.
An analysis of 47 studies involving more than 180,000 participants taking beta carotene, vitamin E and vitamin A indicates that rather than improving health, popping the pills may increase the risk of death.
The report appears in today’s issue of the Journal of the American Medical Association and was compiled by researchers with the Cochrane Collaboration, an international network of experts who conduct systematic reviews of published studies to determine whether current treatments are based on scientific evidence.
The researchers reviewed 68 studies, but sorted out results from the 47 they considered the most credible and found an overall 5 percent increased risk of death. Beta carotene was associated with a 7 percent increased risk; vitamin A, a 16 percent increase, and vitamin E, a 4 percent increase.
Vitamin C and selenium were also included in the analysis and no increased risk of death was found, according to Dr. Goran Bjelakovic, director of medical science at the Center for Clinical Intervention Research in Copenhagen. But people taking vitamin C didn’t necessarily live any longer than people who didn’t take the vitamin.
"Our findings contradict the findings of observational studies claiming that antioxidants improve health," the researchers wrote. There is no evidence that vitamin C increases longevity, they said, and while selenium tended to reduce mortality, more study is needed to confirm the benefit.
The vitamin industry took issue with the methods used in the analysis and with the findings.
"Healthy consumers can feel confident in continuing to take antioxidants for the benefits they provide. This meta-analysis does nothing to change those facts," Andrew Shao, vice president of the Council for Responsible Nutrition, a Washington-based trade association representing ingredient suppliers and manufacturers in the dietary supplement industry.
"While meta-analyses can be useful when the included studies are very similar in design and study population, this meta-analysis combined studies that differ vastly from each other in a number of important ways that compromise the results," Shao said.
The findings in the JAMA article were not a surprise to Dr. Robert Hasty, assistant professor of internal medicine at Nova Southeastern University’s College of Osteopathic Medicine.
"We’ve known about the link between beta carotene in smokers and an increased risk of lung cancer," Hasty said, "and the vitamin E controversy has been going on for a long time."
Hasty noted the so-called HOPE study, for Heart Outcomes Prevention Evaluation — involving 2,500 women and 6,900 men, published in January 2000 — first raised concerns about vitamin E.
"We know from the HOPE study published in the New England Journal of Medicine that [taking vitamin E] showed no benefit and actually worsened outcomes," he said.
Hasty said people who take lipid-soluable vitamins — E, D, A and K — can build up toxic levels of them because they don’t easily leave the body.
Vitamin C is water soluable and doesn’t build up in the body, but Hasty cautioned against taking too much.
"We live in the "stonebelt" of the United States. We have the most kidney stones, and vitamin C has been associated with an increased risk of stones," Hasty said.
Hasty said he takes a multivitamin every day, "but the evidence behind taking it is really not that profound."
The National Institutes of Health estimates that more than one-third of American adults take multivitamin/mineral supplements regularly. Recommendations regarding supplement use from expert groups vary widely, as does the strength of the evidence supporting such guidelines.
And that makes it confusing for people trying to figure out whether they should take vitamins and what kind. In general, health experts say most Americans should get the bulk of their vitamins from food, and should consult their doctors before considering supplements. Some say that taking a multivitamin can’t hurt, but the study does not address the question of multivitamins.
"It’s tough on the general public to figure out what’s good and what’s not," said Richard Polcini, 78, of Hollywood, who had already crossed vitamins A, E and beta carotene off his list after consulting with his doctor and local pharmacists.
"Vitamin A you don’t want to take that because you get enough in a multivitamin, and too much isn’t good. I do take vitamin C," he said, "but some of those other things you can get too much and it can build up."
The researchers said there are several possible explanations for the negative effects found in their analysis. It could be because antioxidant supplements are synthetic and not subjected to the same testing required of medications, or it could be that they interfere with some natural body defense mechanism.
"Better understanding of mechanisms and actions of antioxidants in relation to a potential disease is needed," the researchers said.
"People shouldn’t be taking large doses of anything, but in particular these antioxidants," said Dr. Michael Friedland, dean of the Charles E. Schmidt College of Biomedical Science and regional dean of the University of Miami Miller School of Medicine at Florida Atlantic University in Boca Raton.
Friedland said he doesn’t take vitamins.
"If you eat a normal healthy balanced diet, with fruits and vegetables and whole grains, there’s no real reason to take vitamin supplements," Friedland said. "That’s probably the best thing people can do."