Mursu et al assessed the self-reported use of
15 vitamin and mineral supplements in relation
to total mortality in 38,772 women in the Iowa
Women's Health Study from 1986 to 2008.

The mean age was 61.6 years at baseline.
Taking multivitamins, vitamin B6 and folic
acid, iron, magnesium, zinc, and copper was
associated with a higher risk of total mortality.

Supplemental iron was strongly and dose-
dependantly associated with increased risk
of mortality.
In contrast, supplemental calcium was
associated with decreased risk of mortality.