Dietary Fibre, Gut Microbiota and Cardiovascular Outcomes: Differential Associations by Diabetes Status in Multiethnic Cohorts

AIM: Cardiovascular disease (CVD) is the leading cause of death worldwide, with higher risks in diabetes and prediabetes. We aim to investigate how dietary fibre affects cardiovascular disease (CVD) risk across different diabetes statuses and explore the role of gut microbiota. METHODS AND MATERIALS: We analysed 207 413 participants from four cohorts in three countries, including 7951 with gut microbiota data from two Chinese cohorts. Dietary fibre intake was assessed via validated food frequency questionnaires. Major adverse cardiovascular events (MACE) included non-fatal ischaemic heart disease, heart failure, stroke and cardiovascular deaths. Cox regression examined associations between dietary fibre, CVD mortality and MACE risk, while multivariable analyses evaluated fibre-related microbiota and MACE. RESULTS: Higher dietary fibre intake was associated with reduced CVD mortality (11% per SD) and MACE risk (6%-12% per SD) in individuals with normoglycaemia or prediabetes, but not in those with diabetes (p for interaction = 0.009). An exploratory fibre-related microbiota index, reflecting beneficial microbial genera (e.g., Lachnospiraceae) and reduced pro-inflammatory genera (e.g., Desulfovibrio), was inversely associated with MACE risk across all diabetes statuses (17%-23% risk reduction per SD). However, the exploratory microbiota index correlated with energy-adjusted dietary fibre intake only in non-diabetic individuals. CONCLUSIONS: The varying impact of dietary fibre based on diabetes status underscores the need for personalised nutrition. The exploratory microbiota index reflects the interplay between fibre, gut health and cardiovascular outcomes, suggesting that microbiota-related markers may help identify populations who could potentially benefit from tailored dietary strategies.