Dear Editor

It appears that the decision makers advising the medical profession are ignorant of the physiology of D3 and have come up with advice on D3 supplementation that guarantees a large percentage of the UK population fail to reach even half-physiological serum 25(OH)D3. It bears repeating that D3 is not a drug whose lowest effective dose can be decided only by RCT. Rather, D3 is a pleiotropic hormone with a defined physiological serum level of pro-hormone 25(OH)D3. The physiological level was defined by researchers several years ago, and championed by the late Robert Heaney MD, whose work is summarised here https://www.tandfonline.com/doi/full/10.1080/07315724.2015.1039866 and in a lecture (Vitamin D, Sunshine, Optimal Health: Putting it all Together, 12/09/2014, University of California Television San Diego).

The physiological serum 25(OH)D3 is between 100 and 150 nmol/L. Adherence to advice from supposed expert panels has left the UK population with an annualised mean level of just under 50 nmol/L. Our innate immune system has evolved over 500 million years and is regulated epigenomically by D3: https://www3.uef.fi/documents/696977/913295/2019-12.pdf/56c69648-7e9f-48.... A strong argument can be made that sub-physiological D3 and impaired innate immunity is a driver of the pandemic.

I find, personally, that my serum 25 (OH)D3 reaches a physiological level of 140 nmol/L with a daily supplement of 4000 IU D3. The maximal, physiological rate of production by sunlight on skin is 10 to 20,000 IU pd

From a physiological perspective advising 400 IU pd has no basis in science.

Link:
Re: Covid-19: physiology is ignored in vitamin D's role in treatment and prevention - The BMJ