To preface here, what I'm to share goes beyond what's in the article. That said, I worked for years in a clinical "bone lab" (and at a notable university hospital with respect to this area of research) investigating bone wasting diseases; namely, idiopathic hypercalciuria, and osteopenia & osteoporosis.
Not say that lends me too much authority on the matter, but many of the biological effects of D3 are pretty poorly understood, still. Simplifying a bit, this can be chalked up to the fact that it's roles in molecular networks across the systems are myriad, and of these, many of its (downstream) effects seem -- and, if not, are -- contradictory. (To the initial point, in it's bioactive form, it's classified as a hormone.)
At high dosages, typically what's found it many OTC supplements (5-10K IUs vs 500 IU daily allowance), there is evidence that it facilitates significant bone resorption.
So not only does it not strengthen bones, D3 actively makes it more brittle. Typically, this is linked to inadequate calcium & phosphate minerals to match the excess D3 (and these minerals in excess introduce additional problems of their own).
I didn't cite literature here but it is readily available & abundant (But I can pull some if anyone would like). And, within it, there is a glaring lack of consensus. And hence, why my language is couched in so many conditionals.
One of the big asterisks with most D3 bone density studies(and is applicable to this one) is that they are studying older adults specifically, vs, say, athletes. There are bodybuilders, for example, who swear by high-dose D3.
If you exceed calcium and phosphates intake by an amount sufficient to compensate for the excess D3, does that "do the trick" or is that a bad hack? I've seen certain 9 pills a day multivitamin formulations who deliver much much higher than the daily dose of everything, I think Life Extension sells them, and I'm wondering if they are hip to these facts.... I used to buy their vitamins. Now I just take the ones that are one a day pill instead of 9, and those never exceed the daily IUs.
Another question for you, does supplementation work as intended when our diet is insufficient, or is it just a gimmick? I've always wondered about this. By work, I mean, if you were to have a blood test in two parallel trials, one where you supplemented but had a crappy diet and another where you ate the "perfect" diet that supplied the daily IU needs, would the blood work show equal amount of each mineral/vitamin/etc in both cases?
Wiki on bone resorption says the opposite, not sure at what intake levels though:
>Vitamin D increases absorption of calcium and phosphate in the intestinal tract, leading to elevated levels of plasma calcium,[4] and thus lower bone resorption.
Not say that lends me too much authority on the matter, but many of the biological effects of D3 are pretty poorly understood, still. Simplifying a bit, this can be chalked up to the fact that it's roles in molecular networks across the systems are myriad, and of these, many of its (downstream) effects seem -- and, if not, are -- contradictory. (To the initial point, in it's bioactive form, it's classified as a hormone.)
At high dosages, typically what's found it many OTC supplements (5-10K IUs vs 500 IU daily allowance), there is evidence that it facilitates significant bone resorption.
So not only does it not strengthen bones, D3 actively makes it more brittle. Typically, this is linked to inadequate calcium & phosphate minerals to match the excess D3 (and these minerals in excess introduce additional problems of their own).
I didn't cite literature here but it is readily available & abundant (But I can pull some if anyone would like). And, within it, there is a glaring lack of consensus. And hence, why my language is couched in so many conditionals.