Vitamin D Toxicity

[MudPhud20XX]

Kaplan Biochem says:

"Vitamin D is highly toxic at consumption levels that continuously exceed 10X RDA, resulting in hypercalcemia. Unlike water-soluble vitamins, which are excreted in excess amounts, vitamin D can be stored in liver as 25-hydroxycholecalciferol. The excess vitamin D can promote intestinal absorption of calcium and phosphate. The direct effect of excessive vitamin D on bone is resorption similar to that seen in vitamin D deficiency. Therefore, the increased intestinal absroption of calcium in vitamin D toxicity contributes to hypercalcemia."

So both vitamin D deficiency and too much vitamin D will cause hypercalcemia? It doesn't seem like vitamin D deficiency cause hypercalcemia though. If so, can anyone enlighten me?

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[Jack1919]

AAAgghh, let me know...

 

[CherryRedDracul]

High vitamin D --> excessive activation of osteoblasts expressing RANKL --> excessive osteoclast activity = net bone resorption = hypercalcemia
Low vitamin D --> secondary hyperparathyroidism to correct low Ca2+ levels --> excessive activation of osteoblasts expressing RANKL = net bone resorption = low to normal calcium levels (because it's being corrected physiologically from hypocalcemia)

*Long-standing active vitamin D deficiency (like in chronic renal insufficiency) can cause secondary hyperPTH to transform into tertiary hyperPTH; the parathyroid glands have been working so hard and long that they start to take a life of their own and continue to pump out PTH without regards for feedback mechanisms. In that case, low vitamin D ---eventually-----> hypercalcemia, but that's really a point of no return because the only to correct that would be by the surgical removal of some of the parathyroid glands because vitamin D levels are not gonna regulate them anymore.

 

[Jack1919]

Thank you!!

 

[RufusG]

Where is the evidence that 10X RDA of Vitamin D is toxic ?

In 1999 the American Journal of Clinical Nutrition published a paper by Professor Reinhold Veith with the
title: Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety. He reviews
the whole subject of sunlight and vitamin D and cites many studies of the effects of vitamin D
supplementation. He states:
“If there is published evidence of toxicity in adults from an intake of 250 micrograms (10,000 IU) per day,
and that is verified by the 25(OH)D concentration, then I have yet to find it.”

Find the Call-To-Action at www.grassrootshealth.net where 40 eminent experts suggest that the blood level 25(OH)D should be set higher at 40-60 ng/ml ( 100-150 nmol/L )

Find the report from www.efsa.europa.eu that allows 100 micrograms ( 4,000 IU ) a day for an adult with a safe upper limit of 250 micrograms ( 10,000 IU )

There are 80 illnesses where "lack of sunlight" is implicated
There is evidence that Vitamin D can be used to prevent, treat or cure 40 illnesses
Read more about all this at: www.vitamindwiki.com

.

 

[mcloaf]

Where is the evidence that 10X RDA of Vitamin D is toxic ?

In 1999 the American Journal of Clinical Nutrition published a paper by Professor Reinhold Veith with the
title: Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety. He reviews
the whole subject of sunlight and vitamin D and cites many studies of the effects of vitamin D
supplementation. He states:
“If there is published evidence of toxicity in adults from an intake of 250 micrograms (10,000 IU) per day,
and that is verified by the 25(OH)D concentration, then I have yet to find it.”

Find the Call-To-Action at www.grassrootshealth.net where 40 eminent experts suggest that the blood level 25(OH)D should be set higher at 40-60 ng/ml ( 100-150 nmol/L )

Find the report from www.efsa.europa.eu that allows 100 micrograms ( 4,000 IU ) a day for an adult with a safe upper limit of 250 micrograms ( 10,000 IU )

There are 80 illnesses where "lack of sunlight" is implicated
There is evidence that Vitamin D can be used to prevent, treat or cure 40 illnesses
Read more about all this at: www.vitamindwiki.com

.

Thank you, vitamin D salesman.

Now please go away and let the adults talk.