Researchers at the University of California, San Diego, have found that low levels of vitamin D in the bloodstream are linked to a higher risk of developing insulin-dependent type 1 diabetes. The research made use of 2,000 frozen blood samples. All the individuals were healthy when the blood was drawn many years ago.
The scientists selected 1,000 samples from people who had developed type 1 diabetes In the intervening time. Another 1,000 from people who did not develop diabetes were used as controls. The blood samples were analyzed for their levels of 25-hydroxyvitamin D. People with at least 50 ng/ml of this vitamin D compound in their blood had only half the risk of type 1 diabetes. The researchers suggest that for most people, a supplement of 4000 IU of vitamin D3 per day is enough to bring blood levels to that point. They caution, however, that mega-doses of D should be avoided.
[Diabetologia, Dec. 2012]