[akiddoc]

Vit D deficiency has been linked to everything under the sun (pun intended). The cutoff for "deficiency" is arbitrary and there is insufficient evidence that Vit D supplementation in asymptomatic "deficient" individuals detected by screening with blood tests has improved outcomes: see the USPSTF statement on this for a sober appraisal. I remember reading that more than 40% of the U.S. population is Vit. D "deficient" by the numbers, so it's no surprise that it's prevalent in patients with COVID-19. The correlation might be due to the people who are seriously ill with COVID-19 having pre-existing comorbidities that kept them from being outdoors as much as needed. People who are obese might have their Vit. D sequestered in fat cells. As far as I'm concerned, this is a nothing burger until proven otherwise. There are going to be tons of spurious correlations related to COVID-19. But if you're so inclined, no harm to taking it in an appropriate low dose.

Yes, practically every study ever done on Vitamin D supplementation has been disappointing, no matter what the condition. It "might" be beneficial as an adjunct therapy for depression. It's probably not good for you to be chronically short of it in your diet. Being short throughout your life likely leads to osteoporosis but trying to treat osteoporosis later in life with vitamin D does not seem to work. 

https://www.chop.edu/news/health-tip/vit...hould-know

The kids that we are concerned about are kids with dark skin. They do not make much vitamin D in their skin and American kids do not eat much fish or drink much milk. I usually put my teens with darker skin on 1000 IU of Vitamin D3 a day. For younger kids I use 400-600 IU. I do not do Vitamin D levels except in very unusual circumstances. We don't know what a "normal" level is.

[akiddoc]

Vit D deficiency has been linked to everything under the sun (pun intended). The cutoff for "deficiency" is arbitrary and there is insufficient evidence that Vit D supplementation in asymptomatic "deficient" individuals detected by screening with blood tests has improved outcomes: see the USPSTF statement on this for a sober appraisal. I remember reading that more than 40% of the U.S. population is Vit. D "deficient" by the numbers, so it's no surprise that it's prevalent in patients with COVID-19. The correlation might be due to the people who are seriously ill with COVID-19 having pre-existing comorbidities that kept them from being outdoors as much as needed. People who are obese might have their Vit. D sequestered in fat cells. As far as I'm concerned, this is a nothing burger until proven otherwise. There are going to be tons of spurious correlations related to COVID-19. But if you're so inclined, no harm to taking it in an appropriate low dose.

Yes, practically every study ever done on Vitamin D supplementation has been disappointing, no matter what the condition. It "might" be beneficial as an adjunct therapy for depression. It's probably not good for you to be chronically short of it in your diet. Being short throughout your life likely leads to osteoporosis but trying to treat osteoporosis later in life with vitamin D does not seem to work. 

https://www.chop.edu/news/health-tip/vit...hould-know

The kids that we are concerned about are kids with dark skin. They do not make much vitamin D in their skin and American kids do not eat much fish or drink much milk. I usually put my teens with darker skin on 1000 IU of Vitamin D3 a day. For younger kids I use 400-600 IU. I do not do Vitamin D levels except in very unusual circumstances. We don't know what a "normal" level is.