What is Vitamin D Good For?

Many studies that track healthy people for years have reached the same con­clusion: “People with higher levels of vitamin D have a lower risk of developing type 2 diabetes in the future,” says Tufts Medical Center’s Anastassios Pittas, who is also a professor of medicine at Tufts University’s Sackler School of Graduate Biomedical Sciences.24

But those studies can’t tell if something else about people with low vitamin D increases their risk. So researchers have looked further.

“We and others have done short ­term intervention studies looking at insulin sensitivity, insulin secretion, or similar out­ comes,” says Pittas. “Some have not shown any difference, but others show promise.”