Can supplements nix kidney stones?

Certain bacteria seem to degrade the compound that forms kidney stones. However, the vast majority of commercially available probiotic supplements, which contain a variety of bacteria strains, don't appear to have this effect, according to new research.

During their lifetimes, about 5 percent of adults will get at least one kidney stone-a crystallized mass often made of calcium and a substance called oxalate. The most common method to prevent new kidney stones is to modify a patient's diet so that it includes less oxalate, which comes from plants such as green leafy vegetables.

Studies in the past few decades have suggested that some bacteria that normally live in the intestines can degrade oxalate, says microbiologist Steven Daniel of Eastern Illinois University in Charleston. He suspected that by eating these by eating these strains, a person who has had a kidney stone can decrease his or her chance of getting another one.

Since many commercial probiotic supplements contain bacteria related to those that reduce oxalate, Daniel and his team decided to test several supplements.

The researchers bought seven popular probiotic supplements marketed to people and two similar products sold for pets. They added the supplements to flasks that contained oxalate and bacterial nutrients.

After 48 hours, the scientists measured how much oxalate remained in each flask. Although one supplement degraded all the oxalate, the others degraded negligible amounts.

Daniel notes that it will take further research to identify which characteristics of the oxalate-consuming bacteria make them so effective at degrading the stone-forming compound.--C.B.