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Robin Whittle's avatar

Good levels of circulating 25-hydroxyvitamin D - at least 50 ng/mL 125 nmol/L - are needed to supply the intracrine (inside each cell) and paracrine (to nearby cells, typically of different types) signaling systems of many cell types. I normally mention that many types of immune cell rely on these signaling systems in order to respond to their changing circumstances, but there is an unknown, but probably large (dozens to hundreds), number of cell types which are not involved in immunity for which this is true.

To what extent telomere protection's apparent dependence on good 25-hydroxyvitamin D levels are due to immune cells or to processes in cell types not directly involved in immune responses is probably not known. It doesn't really matter. The body is much healthier with 50 to (for the great majority of people) 100 ng/mL circulating 25-hydroxyvitamin D than with the 5 to 30 or so ng/mL (12.5 to 75 nmol/L) levels of most people who do not supplement vitamin D3 properly and have not recently had extensive UV-B exposure of ideally white skin.

Without vitamin D3 supplements in quantities which are small, but 5 or more times the tiny amounts governments and many doctors recommend, the body has only a fraction of the 25-hydroxyvitamin D (made in the liver from vitamin D3) it needs to run the immune system properly. A "balanced diet" doesn't help, since there is very little vitamin D3/2 in food, whether it is fortified with vitamin D3 (or more likely the more stable but less effective vitamin D2). UV-B skin exposure can produce lots of vitamin D3, but it is difficult to obtain all year round and always damages DNA, so raising the risk of skin cancer.

You can read the research via pages linked to from my "5 neglected nutrients" site https://5nn.info. This includes recommendations from New Jersey-based Professor of Medicine Sunil Wimalawansa on how much vitamin D3 to supplement to attain the 125 nmol/L (50 ng/mL) 25-hydroxyvitamin D (as measured in "vitamin D" blood tests), to ensure that the immune system can work properly, which greatly reduces the risks of serious illnesses of many kinds, including neurodegeneration and sepsis, as well as protecting against problems in pregnancy and early childhood development.

Vitamin D3 cholecalciferol is hydroxylated, primarily in the liver, to 25-hydroxyvitamin D (calcifediol, or "calcidiol") which has a half life in the bloodstream of weeks to months. Neither are hormones. These are not signaling molecules. For a description of 25-hydroxyvitamin D >> calcitriol (1,25-dihydroxyvitamin D) intracrine and paracrine signalling, please see https://vitamindstopscovid.info/00-evi/.

A more detailed explanation of these signaling systems is at: https://vitamindstopscovid.info/02-intracrine/.

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