Posted by Larry Hoover on March 23, 2009, at 19:06:17
In reply to Re: Vitamin D! **Larry Hoover** » garnet71, posted by DG77 on March 23, 2009, at 15:37:20
> Hi Garnet,
>
> I've been a big proponent of Vitamin D lately. It seems like all kinds of research is coming out that demonstrates how ridiculously low the RDA is.Quite correct. It is ridiculously low.
> There is one thing about it that does kinda scare me, though. I've seen numerous references that cite high doses of Vitamin D as a risk factor for kidney stones. What I don't know is how high a dose is required to have this effect. At any rate, I've cut back a little bit on my dosing until I have a chance to have my levels measured. I would continue to having your levels monitored as well just in case.
>
> Here is one of the references I mentioned:
> http://www.mayoclinic.com/health/kidney-stones/ds00282/dsection=causes
> (see "Calcium stones" item)This link between nephrolithiasis and vitamin D supplements is medical folklore. It is plausible, but it is not demonstrated in clinical trials. The only references I find that link vitamin D supps to calcium kidney stones are of the sort "known risk factors include vitamin D supps" blah blah. But if you search clinical trials of high dose vitamin D, there is no link demonstrated. Before there can be nephrolithiasis (stone formation) there must be hypercalciuria (high calcium in urine), but that is very rare. And before there is hypercalciuria, there must be hypercalcemia (high blood calcium), but that is only slightly less rare.
Here's the bottom line.....some people have a genetic defect in their vitamin D receptors, and they can naturally form stones at typical vitamin D intakes. Some people have primary or secondary hyperparathyroidism, and they're vulnerable for other reasons. And such like. If your doctor has not identified you as being at risk for nephrolithiasis, the only way vitamin D is going to cause it to happen is if you have an undiagnosed disorder that creates the vulnerability. And in all the clinical studies I checked, including ones with doses of megadoses of between 100,000 and 600,000 IU/mo, there were no cases.
I would be far more worried about not having enough, than in getting too much.
Lar
poster:Larry Hoover
thread:886672
URL: http://www.dr-bob.org/babble/20090322/msgs/886702.html