“If I have kidney stones, should I take vitamin D?” A recent study looked directly at this question in “stone formers,” who are people with a history of repetitive kidney stones. Dr. David Leaf of Columbia University Medical Center and a group of colleagues from Boston to Portland conducted this study on stone formers, who were also vitamin D deficient. If vitamin D causes kidney stones (a common belief), then how exactly do you treat vitamin D deficient stone formers?
Leaf DE, Korets R, Taylor EN, Tang J, Asplin JR, Goldfarb DS, Gupta M, Curhan GC. Effect of Vitamin D Repletion on Urinary Calcium Excretion among Kidney Stone Formers. Clin J Am Soc Nephrol. 2012 Mar 15.
As the thinking goes, if vitamin D increases urine calcium, then vitamin D is difficult to recommend, as most stone-formers have too much calcium in their urine. However, as the evidence from studies mount proving the benefits of vitamin D, physicians and patients with kidney stones are in a quandary. Should I treat vitamin D deficiency in stone formers or let them stay vitamin D deficient? The question is, does vitamin D increase urinary calcium?
First, the authors reviewed current research on whether physiological doses of vitamin D increase urinary calcium in non-stone formers. They concluded: “Multiple studies have examined the effects of vitamin D among non-stone former and have consistently failed to show an increase in urinary calcium excretion.” That is, in “normals,” vitamin D does not cause kidney stones.
Now their own research. The authors prospectively studied 29 vitamin D deficient stone formers, giving them all 50,000 IU/week of vitamin D2 for eight weeks. They collected multiple lab tests before and after treatment, including the amount of calcium in the urine. The average vitamin D levels before treatment was 17 ng/ml, which increased to 35 ng/ml after the 400,000 IU of vitamin D (50,000 IU/week for eight weeks). Remember this was D2; D3 would have increased vitamin D levels more, in theory.
None of the various measurements of kidney stone formation increased after the 400,000 IU of vitamin D. To quote the authors,
“In conclusion, our results suggest that vitamin D can be repleted in stone formers without causing an increase in urinary calcium excretion. Given the known benefits of vitamin D in maintaining bone health, the potential benefits for cardiovascular, autoimmune, and neoplastic disease, and the findings above indicating it is safe, we feel that vitamin D therapy, if otherwise indicated, should not be withheld simply on the basis of calcium stone disease or hypercalciuria.”
I want to remind readers of what I have written about kidney stones before: chronic acidosis combined with lack of potassium and magnesium in your diet is the most common cause of kidney stones. This line of thinking is based on, among other things, a double blind study on the use of potassium and magnesium in prevention of stones.
Ettinger B, Pak CY, Citron JT, Thomas C, Adams-Huet B, Vangessel A. Potassium-magnesium citrate is an effective prophylaxis against recurrent calcium oxalate nephrolithiasis. J Urol. 1997 Dec;158(6):2069-73.
So, in my opinion, a typical American diet is to blame for many cases of kidney stones; the lack of two minerals in diet (magnesium and potassium) and the lack of adequate fluid intake. If you have ever had a kidney stone, drink eight glasses of water per day and eat lots of vegetables, fruits, seeds, and nuts. As Dr. David Leaf showed, vitamin D is not to blame for your kidney stones.