Kidney Stone Issue

[ascorbicjoe]

My friend went into the ER with back pain and they found some small kidney stones. They said he was severely dehydrated. He lives with no AC and it has been very hot lately.

Online he saw the kidney stone / ascorbic acid stuff and was bitching about it. He likely never took more than a gram a day.

I told him that the dehydration is far the most important factor.

While looking myself, I found a reference to a 2005 study:

* High amounts of supplementary vitamin C may increase men's risk of developing kidney stones. A 2005 study indicated that men who took 1000 mg or more of vitamin C each day were 40% more likely to develop kidney stones than men who took no more than 90 mg a day.

Why would this be true? Anyone seen this study? What other co-factors would a supplementing person be doing. I would be surprised if an ascorbic acid person would not be drinking a lot of water.

Thanks

[Dolev]

If they don't reference the study, I think you could consider it non-existant.

[ascorbicjoe]

http://jasn.asnjournals.org/cgi/content ... 15/12/3225
says VC increases risk for stones, but b6 decreases in men

http://jasn.asnjournals.org/cgi/content ... t/10/4/840
says VC has no correlation to stones, but b6 decreases it in women

This one from Hickey/Roberts speaks on how VC cures stones.
http://www.orthoeurope.com/IBBOM/index. ... pic&tid=75

It always amazes me the large variation on these studies. However, it was curious that many studies with stones do not actually count stones, but oxalate excretion. I would think that oxalate in solution is far better than stones. Heck oxalate in the urine could be from reduction of existing stones!

[ofonorow]

http://jasn.asnjournals.org/cgi/content/abstract/15/12/3225
says VC increases risk for stones, but b6 decreases in men

Had to review my Ridge Regression Multivariate Analysis...

First, in this study's favor is that it comes from Harvard. I mean that.

A perfect 1 to 1 linear relationship between two variables (e.g. kidney stones and vitamin C over 1 g) would be 1.0. The result was 1.41, and it isn't clear to me in what direction (from the abstract) the line varies from linear.

But lets give them the benefit of a doubt and assume that from 45,619 men, and several questionaires, they were able to input this data without significant error. Unless this were a special population, it would be reasonable to assume that less than 5%, and probably less than 1%, of the men consumed more than 1000 mg of vitamin C. (Perhaps this number can be found in the actual study paper).

1 percent of 45,619 is 456. This is probably in the neighborhood of the population in their study who consume more than 1000 mg daily. It might even be smaller. (It is interesting to note how they mention "477,700 person-years of follow-up" - I guess to make their results appear to carry more weight?) But what if the number of C takers was only 10? Found the full text and the number of subjects among the 45,619 who consumed more than 1000 mg vitamin C (mean about 1100mg) was about 190.

They documented 1473 kidney stones "events" in their population prone to stones.

There analysis tries to connect various dietary variables in the larger population to the 1473 events, 190 of which consumed about 1 g of vitamin C. If my understanding if RR M.v.a. is correct, then 1.0 is the perfect 1 to 1 correlation, and if that understanding is correct, then the lower amounts of vitamin C (e.g. < 90 mg is 1.0) have a better correlation between vitamin C intake and kidney stones.

Here is a direct quote from the full-text

After adjusting for age, there was no association between vitamin C intake and the risk of incident stone formation.

They claim that the risk appears after their adjusting the multivariats, and in their view, a higher number (e.g. 1.41 means increased risk).

The relation between vitamin C intake and stones emerged only after the inclusion of dietary potassium in the multivariate analysis; potassium intake was inversely associated with stone formation and was positively associated with dietary vitamin C

It seems to me that trying to draw a conclusion from a single dietary factor, e.g. vitamin C on such a small sample size (190) and only after admittedly fudging the analysis, is questionable at best. If their data is indeed correct, then it might be wise for people taking low vitamin C (around 1 g) to increase their potassium and magnesium.

As we have quoted Pauling elsewhere on the fact that 50% of the stones appear in alkaline urine, and in those cases, ascorbic acid should prevent those stones. In those with acidic urine, taking more of sodium ascorbate would help prevent the formation of stones.

[Ken_RN]

Previous kidney stone thread is here.

[Ralph Lotz]

For those who want the simple oxalate stone cure take 300-400 mg of magnesium and 50mg of B6.

Nutritional Influences on Illness
The Influence of Dietary Minerals on Calcium Oxalate Kidney Stones
by Melvyn R. Werbach, MD