Impact of Plant-Based Diets on Micronutrient Status and Metabolic Health in Adults with Prediabetes: A Randomized Controlled Trial

Project Abstract

This randomized controlled trial evaluated the effects of a well-planned plant-based diet versus a conventional omnivorous diet on micronutrient status and metabolic health in adults with prediabetes over 12 weeks. A total of 180 adults aged 25–65 years with impaired fasting glucose or impaired glucose tolerance were recruited and randomized to either a plant-based intervention (n=90) or a control omnivorous diet (n=90). The plant-based diet emphasized whole-food sources, legumes, soy, whole grains, fruits, vegetables, nuts, and seeds, with fortified options to address potential micronutrient gaps, and included monthly nutrition counseling and tailored meal plans to support adherence. Primary outcomes included changes in micronutrient biomarkers (vitamin B12, 25-hydroxyvitamin D, ferritin, folate, zinc, iodine) and metabolic parameters (fasting plasma glucose, HbA1c, fasting insulin, HOMA-IR). Secondary outcomes encompassed lipid profile, blood pressure, body composition, inflammatory markers (hs-CRP, IL-6), and anthropometric measures. Dietary intake was monitored using 3-day weighed food records at baseline, week 6, and week 12, with adherence assessed via diet compliance scores and plasma carotenoid concentrations as objective biomarkers of plant-based intake. Results demonstrated that the plant-based group achieved superior improvements in glycemic control, evidenced by a greater reduction in HbA1c (-0.5% vs -0.2%, p<0.01) and faster decline in fasting glucose (-12 mg/dL vs -6 mg/dL, p<0.05) compared with controls. Insulin resistance improved more markedly in the plant-based group (HOMA-IR -1.6 vs -0.8, p<0.01). Lipid profiles improved in both groups, with greater reductions in LDL-C (-12 mg/dL vs -6 mg/dL, p<0.05) and triglycerides (-18% vs -9%, p<0.05) in the plant-based arm. Body weight and waist circumference decreased similarly across groups, with no between-group differences. Micronutrient analysis revealed no clinically significant deficits in B12 or iron status in either group, attributable to fortified foods and supplementation where indicated; however, B12 levels declined modestly in the plant-based group without clinical deficiency, while serum ferritin increased modestly, suggesting improved iron stores. Vitamin D status remained stable in both groups, while zinc and iodine levels remained within normal ranges without between-group differences. Inflammatory markers decreased in both cohorts, with greater reductions in hs-CRP and IL-6 in the plant-based group (p<0.05). Adherence to the plant-based diet correlated positively with improved glycemic and inflammatory outcomes (r= -0.42 for HbA1c; r= -0.38 for hs-CRP, both p<0.01). No significant adverse events were reported; adherence challenges included social dining constraints and initial digestive adjustments, which were mitigated with gradual fiber introduction and individualized counseling. The study supports the feasibility and metabolic benefits of a well-structured plant-based dietary pattern in adults with prediabetes, highlighting favorable effects on glycemic control, lipid modulation, inflammation, and micronutrient status when carefully planned and monitored. These findings offer clinical implications for dietary guidelines aiming to prevent progression to type 2 diabetes and underscore the importance of targeted micronutrient fortification and ongoing nutrition support in plant-based dietary strategies.

Project Overview

What This Project Is About

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This project looks at how plant-based diets affect micronutrient levels and overall metabolic health in adults who have prediabetes. It compares a plant-based eating plan to a conventional diet to see which approach better supports blood sugar control, body weight, cholesterol, and nutrient status.

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The Problem It Addresses

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Many people with prediabetes are at higher risk of developing type 2 diabetes and heart disease. Plant-based diets are thought to improve health outcomes, but there is limited clear evidence on their impact on micronutrient status and key metabolic indicators in this group. This study aims to fill that gap and guide dietary recommendations.

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Objectives of the Project

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1. Assess changes in fasting blood glucose and HbA1c over the intervention period.
2. Evaluate shifts in lipid profile (cholesterol and triglycerides).
3. Measure micronutrient status (e.g., iron, zinc, vitamin B12, vitamin D) before and after the diet.
4. Compare adherence, acceptability, and practicality of a plant-based diet versus a standard diet.

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What You Will Do Step by Step

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1. Recruit eligible adults with prediabetes and obtain informed consent.
2. Randomly assign participants to plant-based or control diet groups.
3. Provide dietary guidance and monitor adherence through food diaries and check-ins.
4. Collect blood and anthropometric data at baseline and follow-up.
5. Analyze data to compare metabolic outcomes and micronutrient status between groups.
6. Interpret results in light of practical dietary recommendations.

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Expected Outcome

We expect the plant-based group to show improvements in blood sugar control and lipid levels, with adequate micronutrient status supported by careful planning and supplementation where needed. Findings will inform dietary guidance for people with prediabetes and highlight potential nutrient needs on plant-based diets.