Display Morei study on vitamin D from 2008. I'm afraid the medical community has ignored this and other older studies linkinking vitamin D and the immune system
https://www.sciencedirect.com/…abs/pii/S0098299708000587
Abstract
Vitamin D, the sunshine vitamin, is important for childhood bone health. Over the past two decades, it is now recognized that vitamin D not only is important for calcium metabolism and maintenance of bone health throughout life, but also plays an important role in reducing risk of many chronic diseases including type I diabetes, multiple sclerosis, rheumatoid arthritis, deadly cancers, heart disease and infectious diseases. How vitamin D is able to play such an important role in health is based on observation that all tissues and cells in the body have a vitamin D receptor, and, thus, respond to its active form 1,25-dihydroxyvitamin D. However, this did not explain how living at higher latitudes and being at risk of vitamin D deficiency increased risk of these deadly diseases since it was also known that the 1,25-dihydroxyvitamin D levels are normal or even elevated when a person is vitamin D insufficient. Moreover, increased intake of vitamin D or exposure to more sunlight will not induce the kidneys to produce more 1,25-dihydroxyvitamin D. The revelation that the colon, breast, prostate, macrophages and skin among other organs have the enzymatic machinery to produce 1,25-dihydroxyvitamin D provides further insight as to how vitamin D plays such an essential role for overall health and well being. This review will put into perspective many of the new biologic actions of vitamin D and on how 1,25-dihydroxyvitamin D is able to regulate directly or indirectly more than 200 different genes that are responsible for a wide variety of biologic processes.
When is the last time your doctor checked your vitamin levels Im betting never unless you asked for it!
FM1 - I have some sympathy with this. But I also have sympathy with the people who look at the hard evidence and say there is very little showing a real positive effect. When the randomized - or Mendelian randomized - studies consistently no effect, you can be pretty sure that an observational study showing an effect is biassed. So discard 80% of what you think is evidence for Vitamin D. Even so there remains some evidence, but easy to see why it is dismissed when so much of what people claim as evidence just is not that.
I'm not denying that it is biologically active - everyone agrees that. More difficult to find out what is the overall effect of that activity.