Thus, if you go to the doctor and they measure your Vitamin D levels as sufficient, that definitely is very good Covid-risk news for you personally. If they measure your levels as insufficient, that definitely is very bad Covid-risk news for you personally.
I expect something in this direction is correct, but “definitely” and “very good… very bad” seem likely too strongly worded if you supplement Vitamin D significantly prior to this test. I expect in the relevant studies, a very small percent of people are achieving ‘sufficient’ Vitamin D levels via supplementation. If that is true, then the mechanism by which you’re achieving the test result may be quite different than the mechanism by which Covid-risk is reduced in a way that doesn’t have the same effect.
I do acknowledge that it is possible that all the gigantic correlations are a big coincidence that results from intermediation from some combination of otherwise poor health, other sunlight effects and socioeconomic status, and failing to control for such matters.
This seems to be making the point I made above. In addition to these examples, Vitamin D supplementation may only affect the test result without e.g. causing Vitamin D uptake elsewhere that matters within the body, or something like that.
I expect something in this direction is correct, but “definitely” and “very good… very bad” seem likely too strongly worded if you supplement Vitamin D significantly prior to this test. I expect in the relevant studies, a very small percent of people are achieving ‘sufficient’ Vitamin D levels via supplementation. If that is true, then the mechanism by which you’re achieving the test result may be quite different than the mechanism by which Covid-risk is reduced in a way that doesn’t have the same effect.
This seems to be making the point I made above. In addition to these examples, Vitamin D supplementation may only affect the test result without e.g. causing Vitamin D uptake elsewhere that matters within the body, or something like that.