Professor University of Massachusetts Amherst Amherst, Massachusetts, United States
Objectives: An emerging concept “celobiotic” has highlighted that human gut bacteria play an important role in hydrolyzing and disintegrating dietary fiber matrix and then releasing bioactive compounds to exert health effects.
Methods: To characterize the microbial liberation of bioactive compounds hidden in strawberry soluble fiber, in vitro colonic fermentation combined untargeted metabolomics was employed.
Results: This approach identified urolithin C, a microbial metabolite derived from ellagic acid, indicating that ellagic acid is one of the celobiotics in strawberry soluble fiber. A significant five-fold release of total free ellagic acid from strawberry soluble fiber after pectinase treatment further validated this hypothesis. The successful release and subsequent microbial metabolism of ellagic acid were also observed in human bacterial colonized mice, via quantifying the concentration level of ellagic acid and urolithins in blood, urine and fecal samples. Additionally, individual fecal fermentation studies demonstrated donor-specific variability in the capacity to release ellagic acid from strawberry soluble fiber and convert it into urolithins. Moreover, ellagic acid, as a potential celobiotic, is widely distributed in various sources of dietary fibers with varied abundance.
Conclusions: Overall, our findings provided compelling evidence that the microbial release and metabolism of ellagic acid in strawberry soluble fiber were highly individual-dependent. Understanding this type of gut microbial activity is crucial for fully exploring the health potentials of those hidden bioactive compounds in plant fibers.
