For Vitamin and Mineral Supplementation, Less Is More

In the U.S., few individuals face nutritional deficiencies, yet dietary supplements are a multibillion-dollar industry. To explore the relation between older women's use of dietary supplements and mortality, researchers analyzed data on supplement use collected between 1986 and 2008 from 38,772 participants in the Iowa Women's Health Study (mean age at baseline, 62). Deaths were ascertained annually using state and national death registries. Analyses were adjusted for more than 10 potential confounders including age and alcohol intake.

Self-reported use of at least one dietary supplement daily rose from 63% in 1986 to 85% in 2004 (mean follow-up, 19 years). However, with the exception of calcium, supplement use was not associated with lower …