Assessing metabolic flexibility response to a multifibre diet: a randomised‐controlled trial

Abstract

AbstractIntroductionMetabolic flexibility (MetF), defined as the ability to switch between fat and glucose oxidation, is increasingly recognised as a critical marker for assessing responses to dietary interventions. Previously, we showed that the consumption of multifibre bread improved insulin sensitivity and reduced low‐density lipoprotein cholesterol (LDLc) levels in overweight and obese individuals. As a secondary objective, we aimed to explore whether our intervention could also improve MetF.MethodsIn this study, 39 subjects at cardiometabolic risk participated in a double‐blind, randomised, crossover trial lasting 8 weeks, repeated twice. During each phase, participants consumed either 150 g of standard bread daily or bread enriched with a mixture of seven dietary fibres. MetF response was assessed using a mixed‐meal tolerance test (MMTT), analysing changes in respiratory quotient (∆RQ) measured using indirect calorimetry.ResultsAlthough there were no significant differences in ∆RQ changes induced by dietary fibre between the two diets, these changes were positively correlated with postprandial triglyceride excursion (∆TG) at baseline. Subgroup analysis of baseline fasting and postprandial plasma metabolites was conducted to characterise MetF responders. These responders exhibited higher baseline fasting LDLc levels and greater post‐MMTT ∆TG.ConclusionIn conclusion, although dietary fibres did not directly impact MetF in this study, our findings highlight potential determinants of MetF response, warranting further investigation in dedicated future interventions.