[devaboone]

The problem is that a lot of people taking Vitamin D may not need it. The percentage of the population with vitamin D deficiency depends on your definition of deficiency - and that changes. From large trials in humans, there is very little benefit to most adults in taking Vitamin D. If you are deficient and you are an elderly woman in a nursing home, then yes, we have good evidence that vit D supplementation will help you. If you are a younger healthy male, probably not.

[KerryJones]

Yeah, definitely. And over 99% of them won't have any problem in doing it. A significant problem is that people don't know that they have conditions or problems in the first place -- and when there is very, very little downside, it would be defined as "optionality" in the terms of Nicholas Taleb, and provides something we can do that will help in most cases, or at least, not harm.

[lultimouomo]

Are you saying that you wouldn't suggest supplementing in young deficient males, who are otherwise healthy, or just that the evidence is unclear on the benefits but it's still probably worth supplementing in that case, under medical supervision?