I'd be interested to see the results broken out by racial group. There is evidence that blacks do not metabolize vitamin D the same way that whites do, and the standard test for vitamin D concentration does not measure its bioavailability accurately. This could strongly affect the results depending on the racial distribution of participants. In other words this effect could reduce the significance of the results.
The difference is that the test evaluated 25(OH)D concentration, and not 1,25(OH)D which is the useful (metabolized) compound. There is currently no standard test for the latter, which is why they didn't do it. Though I would prefer to see those results, it would be easier at the present time to parameterize the study by racial group to reduce or eliminate this effect.
That said it would be nice if we could all just take a nice cheap vitamin for this. Caveat: I am not in life sciences.
Here's a popular article on the topic. https://www.npr.org/sections/health-shots/2013/11/20/2463933... though there's plenty of research articles available.
The difference is that the test evaluated 25(OH)D concentration, and not 1,25(OH)D which is the useful (metabolized) compound. There is currently no standard test for the latter, which is why they didn't do it. Though I would prefer to see those results, it would be easier at the present time to parameterize the study by racial group to reduce or eliminate this effect.
That said it would be nice if we could all just take a nice cheap vitamin for this. Caveat: I am not in life sciences.
Edit. They do show a figure which breaks out the relationship by race. https://journals.plos.org/plosone/article/figure?id=10.1371/... and it is much stronger for African Americans. Perhaps my hypothesis was incorrect.