Vitamin D has been touted for its beneficial effects on a range of human systems, from enhancing bone health to reducing the risk of developing certain cancers. But it does not improve cholesterol levels, according to a new study conducted at The Rockefeller University Hospital. A team of scientists has shown that, at least in the short term, cholesterol levels did not improve when volunteers with vitamin D deficiency received mega-doses of vitamin D. The finding is published in the journal Arteriosclerosis, Thrombosis and Vascular Biology.This stuff probably can't do 90% of what it is "touted" to do.
Almost all studies are association studies.
Very few are cause-and-effect.