I think everyone I know who has checked their Vitamin D levels has needed supplementation, and everyone I know who has checked their vitamin D receptors from their genetic testing (mostly white Americans) has been missing one or two of the 4 (VDR).
A doctor I respect once told me that except for the ones who die of skin cancer, people with the most sun exposure are generally the healthiest 🤷 Is it vitamin D? Is it something else? Is the drop in sun exposure a contributing factor in the "flu season"? Is the circadian rhythm support what matters?
If you do decide to supplement, my understanding is that it should be taken with k2. (I use a liquid that has both).
If you need further encouragement: it also looks like Covid outcomes are worse if you are vitamin D deficient, and it can take weeks to get your levels up.
