Oxalobacter Formigenes Colonization and Urinary Oxalate Excretion

The purpose of this research study is to assess the efficacy of ingesting a small amount of the harmless bacterium Oxalobacter formigenes in establishing residence in the guts of human subjects and to determine whether this influences the oxalate passed in urine of healthy volunteers.

Adults that are not colonized with O. formigenes, have no history of stone disease and are in good health as judged by their medical history, a complete metabolic profile of their serum, and ranges of ions that influence stone formation in two 24-hour urine collections, will be recruited from within the greater Birmingham area. Recruited subjects will be between the ages of 18 to 65 years and with a BMI >19 and <32. Subjects not colonized with O. formigenes will consume, firstly, a controlled diet containing 50 mg oxalate and 1000mg calcium (low oxalate/normal calcium diet), followed by a 250 mg oxalate/400mg calcium controlled diet (moderately high oxalate/low calcium diet), with at least a one week washout between each diet, and then repeat the same sequence of diets after colonization with O.formigenes Group 1 strain OxCC13. Controlled diets will be prepared in the Metabolic Kitchen of the UAB Clinical Research Unit (CRU). Sustainability of colonization will be determined over time. Loss of colonization will be confirmed by having the subject consume an oxalate-rich meal with subsequent testing for O. formigenes.

Evaluate urinary oxalate excretion before and after colonization with the oxalate degrading bacterium Oxalobacter formigenes

Subjects not colonized with Oxalobacter formigenes will be equilibrated to a low oxalate diet to determine baseline oxalate values in urine . Subjects will be colonized with Oxalobacter formigenes (Intervention). Following colonization with Oxalobacter formigenes, urinary oxalate will be measured to determine the impact of colonization.

Subjects not colonized with Oxalobacter formigenes will be equilibrated to a moderately high oxalate/ low calcium oxalate diet to enhance dietary oxalate absorption. Subjects will be colonized with Oxalobacter formigenes(Intervention). Following colonization with Oxalobacter formigenes, urinary oxalate will be measured to determine the impact of colonization.

Inclusion Criteria: Good health as judged from a medical history and reported medications Not colonized with O. formigenes Exclusion Criteria: History of any hepatic, renal, bowel or endocrine disease or any other condition that may influence the absorption, transport or urinary excretion of ions, which will compromise the interpretation of results colonized with O. formigenes abnormal urine chemistries or blood metabolic profiles