They are not into the health business, it not profitable if one is, to them. All the medicine one needs is in nature.
Because they have been advocating that for so long it is a given.
Really, when and where? Throughout the 'pandemic', you never heard Fauci et al mention the proven role of Vitamin D in disease prevention.
The Food Pyramid is literally wrong. Show me one documented case of Vitamin D toxicity killing someone. Since the dosage is linked to your BMI, you are unlikely to ever suffer an overdose.
Show me when or where Fauci, the CDC, NIH, or any other public agencies advocated nutrition and vitamin supplementation for the prevention and treatment of Covid 19.