While probiotics consist of strains of good bacteria, prebiotics are carbohydrates that act as nourishment for those bacteria. With more evidence that gut bacteria may exert some influence on brain function and mental health, probiotics and prebiotics are being studied for the potential alleviation of anxiety and depression symptoms.
"Prebiotics are dietary fibers (short chains of sugar molecules) that good bacteria break down, and use to multiply," the study's lead author, Oxford neurobiologist Dr. Philip Burnet, told The Huffington Post. "Prebiotics are 'food' for good bacteria already present in the gut. Taking prebiotics therefore increases the numbers of all species of good bacteria in the gut, which will theoretically have greater beneficial effects than [introducing] a single species."