According to a recent publication as part of the Australian ‘Gut Feelings’ randomized controlled trial, researchers examined 119 adults with moderate psychological distress and low prebiotic food intake in a 4-qrm trial: 1) probiotic supplement and diet as usual 2) high prebiotic diet and placebo supplement 3) probiotic supplement and high prebiotic food (synbiotic) and 4) placebo supplement and diet as usual. They observed that a high prebiotic diet may improve mood, anxiety, stress and sleep whereas the synbiotic combination did not appear to have an effect, postulating that the ingested probiotic bacteria competed with endogenous microbiota for prebiotic dietary substrates.