Calcium, D, & diabetes.

Calcium and vitamin D supplements may lower the risk of diabetes, says a study that tracked 80,000 women for 20 years.

Women who consumed the most calcium (more than 500 mg a day) from supplements had a 20 percent lower risk of diabetes than those who consumed the least (250 mg a day or less). Women who consumed the most vitamin D from supplements (more than 400 IU a day) had a 13 percent lower risk of diabetes than those who consumed the least (less than 100 IU a day).

It's not clear why a lower risk of diabetes was linked only to calcium and vitamin D from supplements, not food. People who take those supplements may do other things--like exercise or stay trim--that lower their risk, but the researchers tried to eliminate those "confounders."

What to do: Until the link with diabetes is clearer, it's worth taking enough calcium and vitamin D to protect your bones.

If you're 50 or younger, shoot for 1,000 mg a day of calcium and 400 IU a day of vitamin D (from food and supplements). If you're over 50, increase the calcium to 1,200 mg. If you're over 70, boost the vitamin D to 600 IU.

Diabetes Care 29: 650, 2006.