I don’t know how plausible the mechanism of action is here, but it’s interesting that Scott mentioned nitric oxide being generated from sunlight as a potential confounder with Vitamin D effects in his COVID/Vitamin D post:
The loose ends that bother me the most are the seasonal pattern, the latitude data, plus the increased risk of hospitalization and death in Asians. I don’t have a great explanation for those. One possibility is that sunlight does help prevent coronavirus, it just isn’t Vitamin D mediated. I suspect that the “anything involving sunlight is Vitamin D” assumption a lot of epidemiologists have isn’t going to hold up very well—this seems especially true for cancer, where sunlight matters a lot but study after study has shown Vitamin D doesn’t help at all. It may also be true for schizophrenia, although I’m going off one really pathetic study there and it could very well turn out to be Vitamin D after all. Some people are doing a little bit of work to clear up what the sunlight-related-Vitamin-D-independent pathways might be; I think nitric oxide has come up a few times.
This would explain the failed RCT and Mendelian randomization. But if it were true, we would expect to see more of a correlation in observational data—the people with more nitric oxide (or whatever) would be the people who get the most sunlight would be the people who have the most Vitamin D.
I’ve been taking l-arginine (gets converted to nitric oxide in the body) for various reasons including this.
I don’t know how plausible the mechanism of action is here, but it’s interesting that Scott mentioned nitric oxide being generated from sunlight as a potential confounder with Vitamin D effects in his COVID/Vitamin D post:
I’ve been taking l-arginine (gets converted to nitric oxide in the body) for various reasons including this.