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By Denise Mann
WebMD Health News
Reviewed by Laura J. Martin, MD
Oct. 10, 2011 -- Some of the supplements that older women take to improve their health may actually raise their risk of death.
In a new study, multivitamins, folic acid, iron, copper, magnesium, zinc, and vitamin B6 supplements all increased an older woman's risk of dying from any cause. The greatest risk was seen with iron supplements. Calcium supplements, however, seemed to reduce a woman's risk of dying.
The study, which appears in the Archives of Internal Medicine, was an observational trial, not a cause-and-effect trial. So it can't say how, or even if, these supplements actually increase a woman's chance of dying.
By all counts, the dietary supplement industry is booming in the U.S. It grosses billions of dollars per year. A growing number of people are taking one or more vitamin, mineral, or herbal supplements in order to maintain or improve their health. Many also turn to these supplements to treat diseases or conditions.
Women who took part in the Iowa Women's Health Study were aged an average of 61.6 in 1986. They answered questionnaires about their supplement use through their 80s. A total of 15,594 women died by the end of December 2008. More women took supplements as they aged, with 62.7% saying they took at least one supplement in 1986 and 85.1% saying they did so in 2004.
Women who took multivitamins, folic acid, vitamin B6, iron, copper, magnesium, and zinc supplements were more likely to die than women who did not take supplements even though they had healthier habits and lifestyles than women who did not supplement their diet with extra vitamins and minerals. Supplement use was likely not an indicator for failing health or disease onset.
Popular Supplements May Be Dangerous to Your Health
"It is a big story," says researcher David R. Jacobs Jr., PhD. He is a Mayo Professor of Public Health in the division of epidemiology and community health at the University of Minnesota School of Public Health in Minneapolis.
Jacobs says the findings may also apply to women -- and men -- of all ages.
His theory is that supplements don't have the same checks and balances as whole foods. Supplements provide a single nutrient in isolation and may be taken in high, potentially toxic doses. Whole foods are balanced with other nutrients.
Too much vitamin B6, for example, on its own may be harmful, but the foods that contain B6, such as avocados, bananas, dried beans, and whole grains, also bring other nutrients to the table that may all work together.
"People may eat well and take supplements for a guarantee, but this wisdom is not wise," he says.
"Supplements are regarded as safe as they come from food, but they do have drug-like effects," Jacobs says. "It would be wise to start treating these as if they are drugs and actually test them." Supplements are not regulated by the FDA in the same manner as drugs in the U.S.
If you can get your nutrients from food, do that, he says. Elderly people who have issues cooking or eating may need supplements, but this should be done under the guidance of their doctor.
Jaakko Mursu, PhD, of the University of Eastern Finland in Kuopio, Finland, and the University of Minnesota, Minneapolis, is also an author on the study. "We would advise people to reconsider whether they need to use supplements and put more emphasis on a healthy diet," he says in an email.
Too Much Iron Dangerous
Not so fast, says Duffy MacKay, ND, the vice president of scientific and regulatory affairs at the Council for Responsible Nutrition, a Washington, D.C.-based trade group representing the dietary supplement industry.
He takes issue with the new study and its findings. "The authors strongly overstated the potential for harm, while understating the benefits. The notion that the use of some supplements increases your risk for mortality is not substantiated by this data," MacKay tells WebMD.
"Eat a healthy diet, fill in the gaps with supplements, and talk to your doctor about figuring it out," he says.
One thing is clear from this study: Supplement users do seem to be healthier in general, he says. "A study that looks at the women who survived would be interesting."
The iron issue seen in the study is a real one, MacKay says.
Many of the women in this study were taking iron at doses that far exceed any recommendations, he says. Too much iron is not recommended for anyone and increases the risk of several diseases, including liver and heart disease.
Joel Danisi, MD, is the clinical director of the division of geriatric medicine at the University of Miami Miller School of Medicine in Florida. He agrees with MacKay regarding the iron issue.
"Iron seems to be the worst offender," he says. "Check with your doctor to see if you are iron-deficient before considering iron supplements."
Less Is More
The bottom line for Susan Fisher, PhD, is this: "A lot of vitamin supplements may not be protective against death, so more is not better." She is the professor and chair of community and preventive medicine at University of Rochester in Rochester, N.Y.
While the women in the study were presumed to be healthy, their supplement use may have actually been the tip-off that their health was changing. "Many people consider visiting the vitamin store because they are feeling tired and this may be the first sign that health is beginning to fail," she says.
Supplements do have a role in treating nutritional deficiencies. "If you have a deficiency, taking dietary supplements probably will be helpful in preventing any outcomes or conditions related to this deficiency," Fisher tells WebMD.
For example, "If you have low calcium, take supplements because they will help build bones and decrease your fracture risk."
Don't Stop Taking Your Multivitamin Yet
The next step is for researchers to determine how much of any given nutrient is too much and why, Miriam Pappo, MS, RD, says in an email. She is the director of the department of clinical nutrition at Montefiore Medical Center in the Bronx, N.Y.
"Getting our nutritional needs through food is of course the ultimate goal, she says. Still, "few can say they meet the micronutrient nutritional guidelines of 5-9 servings of fruits/vegetables daily, which is why many take a multivitamin, and the American Medical Association recommends it for our fast-paced society."
Don't stop taking yours because of this study, Pappo tells WebMD.
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