The popular press is talking about vitamin D as “The Sunshine Vitamin”, promoting it as capable of reducing the risk of cancers and autoimmune disease. Yet vitamin D is actually a secosteroid transcriptional activator, at the heart of the innate immunity.
This looks trivial but it isnÂ´t if you look at the NEJM paper cited above.
the unsupplemental metabolic homeostasis is probably in the range 23-60 nmol/l
which is also close to my estimate. What I did not know so far are the risks discussed with obesity and arthritis. Here is a video from the author