The potentially dangerous ones are iron if you're middle aged and female are: multivitamins, vitamin B6, folic acid, beta carotene, magnesium, zinc, and copper. They used data from the Iowa Women's Health Study, which collected data on 38,772 women aged 55 to 69. From that sample, 15,594 died during the study period, which was about 40% of the initial group! Geeze. The people who took supplements were more educated, more physically active and more likely to get supplemental estrogen. Vitamin B6, folic acid, iron, magnesium, and zinc were associated with about a 3% to 6% increased risk for death, whereas copper was associated with an 18.0% increased risk for total mortality when compared with corresponding nonuse. On the other hand, women who took calcium were more likely to live longer (3.8% risk reduction).
My theory: people take more vitamins when their diet is crap. I know I do this. I'll eat a dinner of popcorn and ice cream and supplements sometimes. But when I eat fresh organic veggies and meat, I skip the supps and don't worry about it. Perhaps we "older" women are using our pills to justify a terrible diet. Maybe? Guess I better start taking my calcium, though.
Absolute risk increase (total mortality) multis 2.4% B6 4.1% folic 5.9% iron 3.9% magnesium 3.5% zinc 3.0% copper 18.0%