5 ms·

I read somewhere that prolonged high doses of vitamin D might have adverse effects on bone strength making them more brittle, but I'm unsure about the source. I

I read somewhere that prolonged high doses of vitamin D might have adverse effects on bone strength making them more brittle, but I'm unsure about the source. I personally have celiac disease and hypothyroidism am also having issues keeping the D up (heh heh). I take about 200ug daily with vitamin K and I'm thinking about increasing it temporarily to double of that. Generally it shouldn't be an issue with short term higher doses, but nearing a 1000ug daily dose for prolonged periods (months) can be dangerous.

teilo 6y ago
That is only true if you also have a potassium deficiency and low K2-MK7. That's why, when testing D levels, it's also important to test Ca levels. And even then, you have to be taking very high levels of D. More on the order of 50K UI a day for a long time.
thornjm 6y ago
(Med student here with only limited knowledge). This is correct. The active form of Vitamin D (Calcitriol) can be both helpful and harmful to bone health. I think the mechanism is not fully understood but in short doses it stimulates bone growth and is a treatment for osteoporosis. In chronic doses it actives cells caused osteoclasts that reabsorb bone.
- woofie11 6y ago
  Do you know the breakpoint? What's a short dose, and when does it become chronic?
- Harvesterify 6y ago
  Cholecalciferol is used in over the counter supplements, not calcitriol (which is the active vitamin D form). There also is a negative feedback for the conversion, that explain why there are so few acute vitamin D poisoning.
macawfish 6y ago
I believe that's why some nutritionists recommend supplementing with Magnesium when taking vitamin D.
watertom 6y ago
Well considering 1 hour of spring, summer fall skin exposure at noon will generate between 10,000 and 20,000 IU of Vitamin D, I’d be interested in what would constitute a high dose. These scientists believe the RDA of 600 IU was a statistical error, and that the correct amount should be 8,995. https://pubmed.ncbi.nlm.nih.gov/28768407/ https://pubmed.ncbi.nlm.nih.gov/28768407/ Considering how much vitamin D is generated during sun exposure, 600 IU seems ridiculously low.

teilo 6y ago

That is only true if you also have a potassium deficiency and low K2-MK7. That's why, when testing D levels, it's also important to test Ca levels. And even then, you have to be taking very high levels of D. More on the order of 50K UI a day for a long time.

thornjm 6y ago

(Med student here with only limited knowledge). This is correct. The active form of Vitamin D (Calcitriol) can be both helpful and harmful to bone health. I think the mechanism is not fully understood but in short doses it stimulates bone growth and is a treatment for osteoporosis. In chronic doses it actives cells caused osteoclasts that reabsorb bone.

woofie11 6y ago
Do you know the breakpoint? What's a short dose, and when does it become chronic?
Harvesterify 6y ago
Cholecalciferol is used in over the counter supplements, not calcitriol (which is the active vitamin D form). There also is a negative feedback for the conversion, that explain why there are so few acute vitamin D poisoning.

macawfish 6y ago

I believe that's why some nutritionists recommend supplementing with Magnesium when taking vitamin D.

watertom 6y ago

Well considering 1 hour of spring, summer fall skin exposure at noon will generate between 10,000 and 20,000 IU of Vitamin D, I’d be interested in what would constitute a high dose. These scientists believe the RDA of 600 IU was a statistical error, and that the correct amount should be 8,995. https://pubmed.ncbi.nlm.nih.gov/28768407/ https://pubmed.ncbi.nlm.nih.gov/28768407/ Considering how much vitamin D is generated during sun exposure, 600 IU seems ridiculously low.