O88 REDUCTION IN SYSTOLIC BLOOD PRESSURE FOLLOWING DIETARY FIBRE INTERVENTION IS DEPENDENT ON BASELINE GUT MICROBIOTA COMPOSITION

Background/Objective: Dietary interventions high in fibre have been shown to lower blood pressure (BP). This effect is via the gut microbiota, via fermentation of fibre and production of metabolites called short-chain fatty acids (SCFAs). Not all patients respond to dietary fibre interventions for unclear reasons. We aimed to determine if we can identify fibre-responders based on their gut microbiota and production of SCFAs. Methods: We performed a phase II cross-over placebo-controlled randomised clinical trial in untreated hypertensive patients. Twenty treatment-naive participants with hypertension received 40 g per day of fermentable fibre delivered as acetylated and butyrylated high amylose maize starch (HAMSAB) or the placebo for 3 weeks. Blood pressure was monitored at baseline and endpoint by ambulatory BP monitoring, with those experiencing a reduction of ≥2 mmHg in systolic BP classified as responders. The microbiota was determined by sequencing the V4-V5 region of the 16S rRNA gene in baseline stool samples. The relationship between baseline gut microbiota and response to dietary intervention was assessed with the MaAsLin2 package. Plasma SCFAs levels were quantified by mass spectrometry. Results: We observed a placebo-subtracted mean 24-hour systolic BP of –6.1 mmHg (p=0.03, reported in Jama et al., 2023 Nature Cardiovascular Research), with 14 (70%) individuals classified as responders and 6 (30%) as non-responders. Genera significantly enriched in responders included Dialister (β=1.29, q=1.921x10-134), Coprococcus (β=1.26, q=3.282x10-121), Bifidobacterium (β=1.67, q=1.11x10-81), Ruminococcus (β=0.161, q=1.11x10-8), and Roseburia (β=0.82, q=4.275x10-2). Responders also produced higher levels of the SCFAs butyrate (mean±SEM, non-responders 4.95±2.4 vs responders 51.15±14.7, p=0.0096), but no difference in other SCFAs. Conclusions: Participants who experienced a decrease in systolic BP following a dietary fibre intervention had increased bacterial genera known to contain species that produce SCFAs (Bifidobacterium, Roseburia, Ruminococcus) at baseline, and were able to produce more butyrate. These data suggest that baseline microbiota composition contributes to the response to dietary fibre intervention trials in people with hypertension, likely via increased capacity to produce butyrate.