FWIW, I started taking Vitamin D without measuring my blood levels after reading https://www.gwern.net/Longevity#vitamin-d . I take 2000 IU/day; the NIH site says the “tolerable upper intake level” is 4,000 IU, so I think I have pretty good margins. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional
OOPS! I misread Chris Masterjohn’s advice. He recommends NO vitamin D supplements until the coronovirus threat is reduced.
FWIW, I started taking Vitamin D without measuring my blood levels after reading https://www.gwern.net/Longevity#vitamin-d . I take 2000 IU/day; the NIH site says the “tolerable upper intake level” is 4,000 IU, so I think I have pretty good margins. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional
OOPS! I misread Chris Masterjohn’s advice. He recommends NO vitamin D supplements until the coronovirus threat is reduced.