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

• Published in: Journal of human nutrition and dietetics Vol. 37; no. 5; pp. 1186 - 1196
• Main Authors: Aubin, Adrien, Hornero‐Ramirez, Hugo, Ranaivo, Harimalala, Simon, Chantal, Van Den Berghe, Laurie, Favier, Nathalie Feugier, Dussous, Isabelle, Roger, Loïc, Laville, Martine, Béra‐Maillet, Christel, Doré, Joël, Caussy, Cyrielle, Nazare, Julie‐Anne
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.10.2024; Wiley
• Subjects: Adult; Aerobic capacity; Aerobic respiration; Anaerobic respiration; Blindness; Blood Glucose - metabolism; Bread; breads; Calorimetry; Calorimetry, Indirect; Carbohydrates; cardiometabolic profile; cardiometabolic risk; Cholesterol; Cholesterol, LDL - blood; Cross-Over Studies; Diabetes mellitus (non-insulin dependent); Diet; Diet - methods; Dietary fiber; Dietary Fiber - administration & dosage; dietary fibre; Dietary guidelines; dietary intervention; dietetics; Double-Blind Method; Energy metabolism; Energy requirements; Energy sources; Energy utilization; Environmental changes; Fasting; Female; Fibers; Flexibility; Glucose; Health risks; Humans; Insulin; Insulin Resistance; Laboratory testing; Life Sciences; low density lipoprotein cholesterol; Male; metabolic flexibility; Metabolism; Metabolites; Middle Aged; mixed‐meal test; Obesity; Obesity - diet therapy; overweight; Overweight - blood; Overweight - diet therapy; Overweight - metabolism; Oxidation; Oxidation resistance; Postprandial Period; Respiration; Respiratory quotient; risk; Subgroups; triacylglycerols; Triglycerides; Triglycerides - blood; cardiometabolic risk; metabolic flexibility; dietary fibre; cardiometabolic profile; mixed‐meal test; dietary intervention
• ISSN: 0952-3871; 1365-277X; 1365-277X
• DOI: 10.1111/jhn.13350

Introduction Metabolic 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. Methods In 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. Results Although 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. Conclusion In 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. An 8‐week multifibre diet did not improve metabolic flexibility in 39 subjects at cardiometabolic risk. However, the subjects with worse lipid profile might be those who would benefit from this intervention. Highlights The term ‘metabolic flexibility’ (MetF) was initially used to describe the ability of helminths to generate energy through either aerobic respiration or anaerobic respiration, enabling them to adapt to environmental changes. This concept was later applied to human metabolism, emphasising the body's capacity to switch between different energy sources, such as carbohydrates and fats, based on energy requirements. MetF has been studied in the context of transitions between fasting and fed states, or in response to insulin stimulation. It refers to the body's ability to adapt its energy utilisation in response to changing metabolic demands. Research has shown that insulin resistance, often linked to type 2 diabetes and obesity, may be associated with reduced MetF, characterised by altered patterns of carbohydrate and fat oxidation.