Probiotics are defined as live microorganisms that confer a health benefit when ingested in sufficient quantities.1 Although probiotics have been touted as having the potential to mitigate declines in kidney function in those with chronic kidney disease (CKD) and diminish many of the adverse biological effects of uremia,2 the usefulness of probiotics to preserve glomerular filtration rate (GFR) has yet to be confirmed in a high-quality intervention trial. Moreover, all reported human probiotic studies have used creatinine-based estimates of GFR.