Vitamin D Supplements and Kidney Stones

By Joel Fuhrman, M.D. www.drfuhrman.com

It is sometimes claimed that taking vitamin D supplements increases the risk of developing kidney stones. There might be a slight increase of risk, but only in people on modern high-protein, low-nutrient, American-style diets. The reason concern comes up is because the Women’s Health Initiative found the relative risk for people taking 400 IUs of vitamin D and 1000 mg of calcium daily was 17 percent higher than in the placebo group.8 However, the participants already had an average baseline calcium intake over 1000 mgs, so the added supplements pushed them into an excessive range of calcium intake. Other vitamin D and calcium trials did not show such a link to kidney stones. It may be the case that taking too much calcium caused the kidney stones. Likewise, people who consume few or no vegetables, but drink soda and eat lots of animal products and highly refined processed foods, are already at higher risk of developing kidney stones.

The largest study that looked at the risk of kidney stones with vitamin D came out of Harvard. It also was a more carefully designed study. They studied 45,616 men over 14 years for a total of 477,000 personyears of follow-up. They found no increased risk of kidney stones with vitamin D intake or with calcium intake.9 They found a link between higher animal protein intake and increased body weight and a link between vitamin C supplements and more stones. But they found protection against kidney stones with a diet with more potassium (46 percent lower relative risk), magnesium (29 percent lower relative risk), and high fluid intake (29 percent lower relative risk). Similar findings occurred when the results for women were published a year later. These larger and more carefully performed studies showed that kidney stones are caused not by increased vitamin D and calcium but by the consumption of animal products, sugar, and harmful nutritional habits.

It may turn out to be the case that excess calcium and vitamin D intake will result in a higher relative risk for kidney stones for people on a very unhealthful version of the modern American diet (low in potassium and magnesium and high in refined carbohydrates, soft drinks, and foods that leave a high acid residue).When you eat such a very unhealthful diet, you may lower your risk of kidney stones by remaining vitamin D deficient, but then you raise your risk of dying from many other diseases even more. The best thing to do to prevent kidney stones is to eat a healthful diet that is naturally low in sodium, rich in minerals, and naturally high in water content. A plant-based, high-nutrient diet naturally keeps your urine alkaline, inhibiting stone formation, too.

References

1. Jackson RD, LaCroix AZ, Gass M, Wallace RB, Robbins J, Lewis CE, et al. Calcium plus vitamin D supplementation and the risk of fractures. N Engl J Med 2006;354:669-83.

2. Taylor EN, Stampfer MJ, Curhan GC. Dietary factors and the risk of incident kidney stones in men: new insights after 14 years of follow-up. J Am Soc Nphrol 2004;15(12):3225-32.

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