> RDA at least three-fourths of the levels proposed by the Endocrine Society Expert Committee as safe upper tolerable daily intake doses.
That seems like a dangerously low margin between recommended and unsafe, no? And they say "at least" like maybe the RDA should be even higher than three-fourths the maximum safe daily dose?
I mean, maybe the human body really does have such a tight tolerance, it really needs 75% of what would be dangerous to maximize health. That would be surprising to me, but could be. It still seems like a recommendation like that is likely to lead to many people exceeding the designated maximum safe daily amount.
(Of course, it could also be that the safe upper tolerable daily intake dose is mistakenly too low?)
> I mean, maybe the human body really does have such a tight tolerance, it really needs 75% of what would be dangerous to maximize health.
Since your body produces Vitamin D from sunlight - and that process is self-limiting - it's certainly biologically possible that the margins really are that small. Historically most people spent far more time outside than we do now.
Unfortunately if that is true, the only reliable way to get the dosing right without expensive testing would probably be sun exposure, which many people simply aren't going to get with modern lifestyles. There's also no evolutionary reason why there couldn't be an inherent trade-off between Vitamin D and UV-related skin damage/skin cancer: evolution tends towards "good enough" rather than "perfect".
Remember that there is no particular expectation of good design in something that wasn't designed in the first place and that a pre civilized human would have encountered only a small number of other humans and would have been primarily considered a success or failure as far as fitness depending on ability to breed in your 20s not living to 85.
What is optimal for us may differ substantially from what might have been optimal for our ancestors.
Also consider that vitamin D from sunlight would likely have been a bigger component and that is naturally slackened by tanning reducing vitamin d production/need to stay out of the sun to avoid getting burned/overheated. Basically it would be harder to get too much.
That seems like a dangerously low margin between recommended and unsafe, no? And they say "at least" like maybe the RDA should be even higher than three-fourths the maximum safe daily dose?
I mean, maybe the human body really does have such a tight tolerance, it really needs 75% of what would be dangerous to maximize health. That would be surprising to me, but could be. It still seems like a recommendation like that is likely to lead to many people exceeding the designated maximum safe daily amount.
(Of course, it could also be that the safe upper tolerable daily intake dose is mistakenly too low?)