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Vitamin supplements associated with higher death rates in older women

Kathleen Blanchard's picture

A study released in the Archives of Internal Medicine links multivitamin use among older women to an increased risk of dying.

In an analysis of 39,000 women who were followed for 19 years, researchers from University of Minnesota found more older women who were taking vitamin B6, folic acid, magnesium, zinc, copper and iron died, compared to women not taking the vitamins.

Iron supplements were especially linked to increased risk of death, even though women using vitamin supplements tended to be healthier overall.

The only supplement that wasn’t linked to a higher chance of dying was calcium.

First author Jaakko Mursu, a postdoctoral researcher in nutrition at the University of Minnesota's School of Public Health and colleagues analyzed data from the Iowa Women's Health Study, which started in 1986. The purpose of the study is to identify risk factors for cancer.

The women, whose average age was 62, answered questionnaires about their health, diet and use of vitamin supplements.

At the beginning of the study, 65 percent of the women were taking one supplement; by 2004, the percentage increased to 85%.

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According to Mursu, "This paper contributes to the growing amount of studies showing no benefits for supplement use in the prevention of chronic diseases.”

The researchers aren’t sure why iron supplements were linked to higher risk of dying. Mursu said it may be that iron is toxic in higher amounts, or the women using the supplements may have had underlying disease that increased the risk of dying. We don't have the detailed information why the women were using it."

The research doesn’t prove women who take vitamin supplements are at risk for dying. Past studies have shown people who take vitamin supplements are also more likely to engage in risky health behaviors.

The authors concluded: "In older women, several commonly used dietary vitamin and mineral supplements may be associated with increased total mortality risk; this association is strongest with supplemental iron. In contrast to the findings of many studies, calcium is associated with decreased risk."

Past studies link vitamin use to risky health behaviors

In a study led by Wen-Bin Chiou of National Sun Yat-Sen University, published by the American Psychological Association, April 2011, researchers found that even though vitamin supplement use is on the rise, there doesn’t seem to be a correlation between taking supplements and increased public health.

Chiou said, “People who rely on dietary supplement use for health protection may pay a hidden price, the curse of licensed self-indulgence. After taking dietary supplements in the morning, individuals should diligently monitor whether illusory invulnerability is activated by restored health credentials and subsequently licenses health-risk behaviors.”

The current study supports that taking vitamin supplements doesn’t extend life or prevent disease. In the current study, more women taking vitamin B6, folic acid, magnesium, zinc, copper and iron died, compared to women not using vitamin supplements.

Image credit: Morguefile