I take vitamin D3. I haven't noticed any improvements, though MG fluctuates so much for other reasons that I can't be sure--maybe I'd be worse without it, who knows. But the study said that MG patients tend to be low on D3 (which I was, according to my blood tests). Even if it doesn't noticeably improve your symptoms, it might protect you from other autoimmune diseases, or from osteoporosis, or from the flu.

Abby