BIOME
Diets low in diverse fibre-rich plant foods are a major factor in the rise of chronic diseases globally. The BIOME study (NCT06231706) was a 6-week, parallel design randomised controlled trial in 399 healthy adults in the UK, investigating a simple dietary intervention containing 30+ whole-food ingredients high in plant polyphenolic compounds, fibre and micronutrients. Participants were randomised to the primary intervention (prebiotic blend; 30g/d) or control (bread croutons; 28g/d; isocaloric functional equivalent) or a daily probiotic (L. rhamnosus). The primary outcome was change in 'favourable' and 'unfavourable' microbiome species compared to control, secondary outcomes included changes in blood metabolites, gut symptoms, stool output, anthropometric measures, subjective hunger, sleep, energy and mood. A crossover test meal challenge sub-study was conducted in 34 participants, investigating postprandial glucose responses, subjective hunger, satiety and mood.  In the 349 male and female participants (mean age 50yrs) included in the analysis (intention-to-treat), self-reported adherence was high (> 98% for all treatments). Following the prebiotic blend, significant improvements were seen in the change and ranking of 'favourable' and 'unfavourable' species as well as beta diversity (weighted-UniFrac measure), but not in the control or probiotic group. There were significantly greater improvements in self reported indigestion, constipation, heartburn, flatulence and energy, following the prebiotic vs control, and hunger following the prebiotic vs probiotic. Addition of the prebiotic to a high carbohydrate test meal challenge resulted in significant improvements in subjective hunger, fullness, and energy (3h incremental area under the curve). No other significant differences between groups were observed.  This prebiotic blend is a simple dietary strategy that benefits gut microbiome composition, gut symptoms and self-reported energy and hunger.