In a 1st, trial finds vitamin D supplements may slow multiple sclerosis. But questions remain.

A close-up image of a person pouring yellow pills onto their hand out of a green-tinged bottle. .

For the first time, a clinical trial has demonstrated that taking high doses of vitamin D may slow the progression of multiple sclerosis.

In general, taking too much vitamin D can be dangerous; however, the high doses in the new trial were taken in controlled conditions, under the supervision of medical staff, and by patients for whom it was deemed safe.