Probiotic-induced reduction of gastrointestinal oxalate absorption in healthy subjects

Joseph Okombo, Michael Liebman

Both a high dietary oxalate intake and increased intestinal absorption appear to be major causes of elevated urine oxalate, a risk factor for kidney stone formation. By favorably altering the gastrointestinal bacterial population, probiotics have the potential to lower oxalate absorption/urinary excretion. This study assessed whether a 4-wk daily consumption of a commercially available probiotic by 11 healthy volunteers (8 females, 3 males), aged 21-36 y, would decrease oxalate absorption. The study involved the ingestion of a probiotic (VSL#3) for a 4 wk period followed by a 4 wk washout period. Oxalate load tests, providing a total of 80 mg oxalate, were conducted at baseline (pre-probiotic), and after the probiotic and washout periods. In the total subject population, mean total 22 h oxalate absorption at baseline (30.8 %) was significantly higher than after the probiotic (11.6 %) and washout (11.5 %) periods. However, four subjects identified as high oxalate absorbers at baseline had a particularly marked probiotic-induced reduction in oxalate absorption, which largely accounted for the reduction observed in the total subject population. The overall data suggested that in individuals characterized by high oxalate absorption levels, VSL#3 ingestion has the potential to reduce gastrointestinal oxalate absorption, which could decrease risk of kidney stones and other disorders related to hyperoxaluria.