Some Dietary Supplements Up Mortality Risk in Older Women
Several common vitamin, mineral supplements increase mortality risk; calcium lowers risk
TUESDAY, Oct. 11 (HealthDay News) -- Intake of certain common dietary vitamin and mineral supplements among older women is associated with increased mortality risk, according to a study published in the Oct. 10 issue of the Archives of Internal Medicine.
Jaakko Mursu, Ph.D., from the University of Eastern Finland in Kuopio, and colleagues investigated the effect of vitamin and mineral supplement intake on total mortality in 38,772 older women (mean age, 61.6 years at baseline) in the Iowa Women's Health Study initiated in 1986. Self-reported data on supplement intake was collected via questionnaires in 1986, 1997, and 2004. A total of 15,594 (40.2 percent) deaths occurred during follow-up through 2008.
The investigators found that, compared with nonuse, there was an increase in the risk of total mortality with use of multivitamins (hazard ratio [HR], 1.06; absolute risk increase [ARI], 2.4 percent), vitamin B6 (HR, 1.10; ARI 4.1 percent), folic acid (HR, 1.15; ARI 5.9 percent), iron (HR, 1.10; ARI, 3.9 percent), magnesium (HR, 1.08; ARI 3.6 percent), zinc (HR, 1.08; ARI, 3 percent), and copper (HR, 1.45; ARI 18 percent) in multivariable adjusted proportional hazard regression models. Use of calcium was associated with decreased risk (HR, 0.91; ARI, 3.8 percent). Estimated risks for calcium and iron were replicated in separate 10-year, six-year, and four-year analyses, each with approximately 15 percent of the original participants having died, starting in 1986, 1997, and 2004.
"Several commonly used dietary vitamin and mineral supplements were associated with increased total mortality rate, most strongly supplemental iron; calcium showed some evidence of lower risk," the authors write.
One of the authors disclosed a financial relationship with the California Walnut Commission.