High-Molecular-Weight Pectin Alleviates Fiber-Free High-Fat Diet-Induced Obesity by Regulating the Colonic Microenvironment and Spatial Microbiota Distribution.

HAP more strongly improved body weight gain than LAP in young C57BL/6J mice fed a fiber-free high-fat diet.

• Young C57BL/6J mice were used in a fiber-free, high-fat-diet (FF-HFD) model
• Both HAP and LAP were compared as dietary interventions against FF-HFD-induced obesity
• HAP produced greater reductions in body weight gain compared to LAP
• The model used was specifically fiber-free to isolate the effects of pectin supplementation

HAP more effectively improved glucose homeostasis and lipid abnormalities than LAP under fiber-free high-fat feeding conditions.

• FF-HFD disrupted glucose homeostasis and caused lipid abnormalities in the mouse model
• HAP supplementation led to greater normalization of glucose homeostasis compared to LAP
• Lipid abnormalities were more strongly corrected by HAP than by LAP
• These metabolic improvements were observed in the young C57BL/6J cohort

HAP enhanced intestinal barrier markers and reduced systemic inflammation compared to LAP.

• HAP was accompanied by enhanced barrier markers relative to LAP treatment
• Reduced systemic inflammation was observed with HAP supplementation
• Lower brain LPS levels were found in HAP-treated mice compared to controls and LAP-treated mice
• These effects suggest HAP better preserved intestinal barrier integrity under FF-HFD conditions

HAP partially normalized fecal microbiota composition and fermentation outputs disrupted by FF-HFD.

• FF-HFD disturbed fecal microbiota composition and fermentation outputs
• HAP supplementation led to partial normalization of these microbiota measures
• LAP produced weaker effects on microbiota normalization compared to HAP
• Fermentation outputs (likely short-chain fatty acids or related metabolites) were partially restored by HAP

HAP partially restored proximal-to-distal luminal microbiota spatial distribution patterns disrupted by FF-HFD.

• Segment-resolved profiling was used to assess spatial microbiota distribution along the colon
• FF-HFD disrupted normal proximal-distal luminal microbiota patterns
• HAP partially restored these spatial microbiota distribution patterns
• This spatial (segment-resolved) profiling approach revealed colonic microenvironment effects not captured by fecal sampling alone

In an aged mouse cohort, HAP alleviated obesity-associated hepatic steatosis and behavioral deficits.

• A separate aged cohort was used to test HAP efficacy beyond young mice
• HAP supplementation alleviated hepatic steatosis associated with obesity in aged mice
• Behavioral deficits associated with obesity were also reduced by HAP in aged mice
• These findings extend the relevance of HAP intervention to aging populations under high-fat, fiber-deficient feeding

Pectin molecular weight determines the efficacy of pectin-based dietary interventions under fiber-deficient high-fat feeding conditions.

• High-molecular-weight apple pectin (HAP) was compared directly with low-molecular-weight pectin (LAP)
• HAP consistently outperformed LAP across multiple metabolic, inflammatory, barrier, and microbiota outcomes
• The authors describe molecular weight as 'a practical lever to optimize pectin-based interventions under fiber-deficient, high-fat feeding'
• The fiber-free model was specifically chosen to test pectin effects in isolation from other dietary fibers