Every 5 ng/ml increase in blood vitamin D was associated with a 1% decrease in inflammatory T cells. Note: 10,400 IU is actually a pretty high dose of Vitamin D! Many of these people were severely deficient to start with. In fact, MS has been linked to genetically low vitamin D…meaning a gene that converts vitamin D into active vitamin D hormone does not work well in many MS patients so they need an unusually high dose of vitamin D. While an ideal dose of Vitamin D may be hard to pin down because of individual variation, what IS known is a generally ideal level. Most studies seem to show a reduction in all-cause mortality (or improvements of various outcomes) when blood status is above 40ng/ml but not in excess of 60ng/ml. I’ve referred to this as the Vitamin D sweet spot before and I think it makes a good argument for blood testing occasionally.