Investigation of the effects of a prebiotic supplementation with black elderberry extract on composition and function of human gut microbiota

The intestinal microbiome is a central factor in human physiology. Deviations in its composition and function from the steady state have been associated with various disease conditions. Based on these findings, there is growing interest in mechanisms with the potential to influence microbiome composition and function, aiming at correcting aberrations and providing beneficial health effects. Prebiotic interventions are promising microbiota-directed treatments, defined as substrates with selective utilization by specific microorganisms conferring a health benefit to the host. Polyphenols are a group of chemical compounds for which prebiotic properties have been reported. European black elderberries which are rich in certain polyphenols are considered a natural remedy in different cultures and the positive health effects of extracts from these fruits have been investigated and reported. Black elderberry extract (ElderCraft®), standardized regarding content of polyphenols and anthocyanin, is available and enabled characterization of the interaction of the extract with the human intestinal microbiome and the host, ultimately aiming at a better understanding of the complex processes underlying its individualized underlying prebiotic effects. The ELDERGUT Trial was designed as a 9-week longitudinal crossover intervention study. A baseline 3 week observational period was followed by a 3 week intervention period which included daily intake of the prebiotic preparation (300 mg extract twice a day). A final 3 week washout phase enabled discrimination between transient and more permanent effects. Study visits were conducted weekly and information on gastrointestinal symptoms, a stool diary as well as biological samples were collected. Outcome parameters included participant-reported outcome data and 16S amplicon metagenomic sequencing.