At the same time, in one study of people with MS, half of participants received daily supplements containing 1,000 international units (IUs) of vitamin D, and the other half received a total of 7,000 IUs of vitamin D per day. At the end of six months, both groups had adequate blood levels of vitamin D. But the group that received the higher doses of vitamin D actually had more relapses and worse disability than the group that received 1,000 IUs per day. More study is needed.
In addition to supplements, you can get vitamin D by eating foods that contain it (such as fatty fish, eggs and fortified dairy products and orange juice) or simply by going outside, where your skin can synthesize vitamin D from sunlight. Consult your doctor for more information about vitamin D and your own needs for it.