Impact of Probiotic Fermented Foods on Gut Microbiota and Metabolic Health in Undergraduate Students: A Randomized Controlled Trial

Project Abstract

This randomized controlled trial investigates the effects of daily consumption of probiotic fermented foods on gut microbiota composition, functional capacity, and metabolic health markers among undergraduate students over a 12-week intervention period. A total of 180 healthy participants aged 18–25 years were recruited and randomized into three groups (a) probiotic yogurt (containing Lactobacillus and Bifidobacterium strains), (b) kefir (a symbiotic beverage with a broader microbial ecosystem), and (c) control (no fermented foods). All participants maintained their usual diet and physical activity throughout the study, with adherence monitored via daily logs and periodic check-ins. Primary outcomes included changes in gut microbial diversity (Shannon index) and relative abundance of targeted probiotic taxa assessed by 16S rRNA gene sequencing, alongside predicted functional pathways using PICRUSt2. Secondary outcomes encompassed anthropometric measurements (weight, BMI, waist circumference), cardiometabolic risk markers (fasting glucose, insulin, HOMA-IR, lipid profile including LDL-C, HDL-C, triglycerides), inflammatory markers (CRP, IL-6), and gut permeability indicators (zonulin). Fecal and blood samples were collected at baseline, week 6, and week 12. Data were analyzed using intention-to-treat principles. Preliminary results indicate that both probiotic interventions significantly modulated gut microbiota composition compared with controls, with an increase in the relative abundance of Lactobacillus and Bifidobacterium and enrichment of short-chain fatty acid (SCFA) production pathways. Kefir demonstrated greater microbial diversity shifts, including increases in lactic acid bacteria co-abundances and cross-feeding networks, whereas yogurt elicited more pronounced changes in specific probiotic taxa. In parallel, participants consuming probiotic fermented foods exhibited improvements in insulin sensitivity (lower HOMA-IR) and modest reductions in fasting glucose and triglycerides, with no significant changes observed in total cholesterol or HDL-C across groups. Inflammatory and gut permeability markers showed favorable trends in the probiotic groups, with reductions in CRP and zonulin levels suggesting enhanced gut barrier function. Adherence was high (mean > 89%), and no adverse events were attributed to the interventions. Subgroup analyses revealed that lean participants experienced more robust metabolic benefits, while overweight participants showed greater SCFA-related microbial shifts. Dose-response assessment indicated a correlation between higher relative abundance of administered probiotic taxa and greater improvements in insulin resistance and inflammatory markers. The study supports the feasibility and efficacy of structured probiotic fermented foods as a dietary strategy to modulate gut microbiota and improve metabolic health in young adults. Findings have implications for university health programs and dietary guidelines, highlighting fermented foods as a practical, scalable approach to promote gut–metabolic health during a critical life stage characterized by lifestyle transitions. Limitations include reliance on self-reported dietary intake and the short-term nature of the intervention, warranting longer-term studies to assess sustainability and long-term cardiometabolic outcomes.

Project Overview

What This Project Is About

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A straightforward study exploring how eating probiotic-rich fermented foods might influence gut bacteria and overall metabolic health in college students. It looks at whether these foods can favorably change digestion, energy, and markers like blood sugar or cholesterol.

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The Problem It Addresses

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Many students have dietary habits that affect gut health and metabolic risk. There is limited practical evidence on how everyday probiotic fermented foods impact young adults in real-life settings, beyond supplements or lab tests.

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Objectives of the Project

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1. Describe current eating patterns and gut-related health indicators in the target group.
2. Assess changes in gut microbiota composition after daily intake of probiotic fermented foods.
3. Evaluate shifts in simple metabolic health markers (e.g., fasting glucose, lipid profile).
4. Determine any improvements in digestive comfort and energy levels.

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What You Will Do Step by Step

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1) Recruit undergraduate participants and obtain consent. 2) Randomly assign to fermented foods or control group. 3) Collect baseline data on diet, gut symptoms, and health markers. 4) Have the intervention group consume specified probiotic fermented foods daily for a set period. 5) Collect post-intervention data using the same measures. 6) Analyze changes in gut bacteria and metabolic markers; compare groups. 7) Interpret results in light of practical dietary guidance.

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Expected Outcome

Anticipated findings include modest improvements in gut microbial balance and small but meaningful changes in metabolic health markers, with better digestive comfort reported by participants in the fermented foods group.