Most studies are flawed. We don't know that Vitamin D works. We also don't know that it doesn't work.
Therefore, we need to consider either possibilities. Given that it is such a low-risk intervention, even a 99% chance that Vitamin D doesn't work would make supplementing worthwhile.
Therefore, we need to consider either possibilities. Given that it is such a low-risk intervention, even a 99% chance that Vitamin D doesn't work would make supplementing worthwhile.