A Plant-Based Diet in the Treatment of Coronary Microvascular Dysfunction

A Plant-Based Diet in the Treatment of Coronary Microvascular Dysfunction (CMD)

This study will evaluate whether a fully provided, unrefined, polyphenol-rich plant-based diet can improve blood vessel function in adults with coronary microvascular dysfunction (CMD), a condition that causes reduced blood flow in the small vessels of the heart despite the absence of major coronary artery blockages.

Participants will follow the diet for 12 weeks while continuing their usual medical care. Researchers will assess changes in vascular function, symptoms, blood pressure, blood lipids, and other health measures throughout the study.

Participants have up to 60 days after consent to complete screening and pre-intervention baseline assessments, potentially over two visits. Day 0 is counseling/education, and diet initiation. Weeks 4, 8, and 12 are measured from Day 0.

Study Overview

• Status: Not yet recruiting
• Conditions: Coronary Microvascular Dysfunction
• Intervention / Treatment: Other: Polyphenol-Rich Plant-Based Diet

Detailed Description

Coronary microvascular dysfunction (CMD) is characterized by impaired coronary microvascular vasodilation and reduced coronary flow reserve in the absence of obstructive epicardial coronary artery disease. CMD is a common cause of ischemic symptoms and is associated with persistent angina, reduced quality of life, and increased cardiovascular risk. Existing therapies are largely directed toward symptom management, and additional strategies that address underlying disease mechanisms are needed.

Oxidative stress, impaired nitric oxide bioavailability, and abnormalities in vascular function are believed to contribute to CMD pathophysiology. Diets rich in unrefined plant foods contain polyphenols and other bioactive compounds that may favorably affect vascular biology, endothelial function, and redox balance. However, the effects of a polyphenol-rich plant-based dietary intervention in individuals with CMD have not been well characterized.

The purpose of this study is to evaluate the effects of an unrefined, polyphenol-rich plant-based dietary pattern on vascular function in adults with CMD and to explore potential biological pathways associated with response to the intervention. The study will also assess the impact of the dietary intervention on symptoms, cardiometabolic health, and measures related to vascular and redox biology.

Findings from this study may improve understanding of the role of dietary modification as a potential adjunctive approach for CMD and help inform future dietary and lifestyle interventions targeting coronary microvascular disease.

• Study Type: Interventional
• Enrollment (Estimated): 20
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Rami S Najjar, PhD; Phone Number: 678-235-4609; Email: rnajjar@emory.edu
• Study Contact Backup: Name: Rami Najjar; Email: rnajjar@emory.edu

Study Locations

• United States
  • Georgia
    • Atlanta, Georgia, United States, 30322
      • Emory University
      • Contact: Rami Najjar, PhD; Phone Number: 678-235-4609; Email: rnajjar@emory.edu
      • Sub-Investigator: Puja Mehta, MD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Women must be postmenopausal.
• History of angina, ischemic symptoms, or symptoms consistent with ischemia in the absence of obstructive coronary artery disease.
• No obstructive coronary artery disease (<50% stenosis in any epicardial coronary artery or fractional flow reserve >0.80).
• Clinically documented coronary microvascular dysfunction (CMD), including coronary flow reserve <2.5 and/or index of microcirculatory resistance ≥25, or equivalent documentation in the medical record.
• Stable cardiometabolic medication regimen for at least 2 months before enrollment.
• Willingness to consume the study-provided plant-based diet and complete all study procedures.
• Ability to provide informed consent

Exclusion:

• Obstructive coronary artery disease or prior coronary revascularization (PCI or CABG).
• Recent acute coronary syndrome, unstable angina, decompensated heart failure, or other clinically unstable cardiovascular disease.
• Significant structural heart disease, uncontrolled arrhythmia, severe uncontrolled hypertension, or symptomatic hypotension.
• Severe renal disease (eGFR <30 mL/min/1.73 m²) or significant liver disease.
• Current vegetarian or vegan diet, or habitual consumption of ≤4 servings of animal products per week.
• Severe food allergies, dietary restrictions, or gastrointestinal conditions that would prevent adherence to the study diet.
• Current use of weight-loss medications, including GLP-1 receptor agonists.
• Active eating disorder.
• Recent (>5%) intentional or unintentional weight change within the previous 3 months.
• Participation in another interventional study that could affect study outcomes.
• Any medical, psychiatric, or social condition that, in the investigator's judgment, would make participation unsafe or interfere with study completion.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Plant-Based Diet Intervention; Participants with clinically documented coronary microvascular dysfunction (CMD) will receive a fully provided, weight-maintaining, unrefined, polyphenol-rich plant-based diet for 12 weeks while continuing clinician-directed medical care. The dietary intervention emphasizes fruits, vegetables, legumes, whole grains, nuts, and seeds and excludes animal products and highly processed foods. Participants will also receive dietary counseling and vitamin B12 supplementation. Participants have up to 60 days after consent to complete screening and pre-intervention baseline assessments, potentially over two visits. Day 0 is counseling/education, and diet initiation. Weeks 4, 8, and 12 are measured from Day 0

Other: Polyphenol-Rich Plant-Based Diet; A fully provided, weight-maintaining, unrefined, polyphenol-rich plant-based dietary intervention administered for 12 weeks. The diet is designed around whole plant foods, including fruits, vegetables, legumes, whole grains, nuts, and seeds, and excludes animal products, refined grains, added sugars, sugar-sweetened beverages, and commercially processed plant-based meat or cheese substitutes. Participants receive nutrition education, ongoing dietary counseling, meal provision, and vitamin B12 supplementation throughout the intervention period

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Brachial Artery Flow-Mediated Dilation (FMD)	Brachial artery flow-mediated dilation (FMD) will be assessed by ultrasound and reported as the percentage increase in brachial artery diameter from the resting pre-occlusion diameter to the peak post-occlusion diameter. FMD is a continuous physiological measurement. Higher FMD percentages indicate greater endothelium-dependent vasodilation and better peripheral endothelial function. Change from baseline will be calculated as the FMD percentage at each post-baseline visit minus the baseline FMD percentage and reported in percentage points.	Baseline (pre-intervention), Week 4, Week 8, and Week 12

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Cutaneous Microvascular Function	Cutaneous microvascular function will be assessed using laser Doppler flowmetry during standardized local heating. Mean cutaneous vascular conductance during the stable local-heating plateau will be calculated by dividing laser Doppler flux by concurrently measured mean arterial pressure and reported in perfusion units per millimeter of mercury (PU/mmHg). Cutaneous vascular conductance is a continuous physiological measurement. Higher values during local heating indicate greater cutaneous microvascular vasodilatory responsiveness. Change from baseline will be calculated as the value at each post-baseline visit minus the baseline value.	Baseline, Week 4, Week 8, and Week 12
Change in Digital Endothelial Function	Digital endothelial function will be assessed using peripheral arterial tonometry and reported as the Reactive Hyperemia Index (RHI). RHI is a continuous, dimensionless physiological index derived from the post-occlusion digital pulse-amplitude response and normalized to the control finger. RHI has no fixed minimum or maximum. Higher RHI values indicate better digital endothelial function. Change from baseline will be calculated as the value at each post-baseline visit minus the baseline value.	Baseline, Week 4, Week 8, and Week 12
Change in Central Arterial Stiffness	Central arterial stiffness assessed by carotid-femoral pulse wave velocity (PWV) using the SphygmoCor system. Pulse wave velocity will be analyzed in meters per second, with lower values reflecting lower arterial stiffness.	Baseline, Week 4, Week 8, and Week 12.
Change in Systemic Redox Status	Plasma aminothiol redox status measured by concentrations of reduced and oxidized aminothiol species, including cysteine, cystine, glutathione, and glutathione disulfide.	Baseline, Week 4, Week 8, and Week 12.
Change in Total cholesterol concentration	Fasting blood total cholesterol concentration will be measured at baseline and each post-baseline assessment. Change from baseline will be calculated as the post-baseline concentration minus the baseline concentration and reported in milligrams per deciliter (mg/dL).	Baseline, Week 4, Week 8, and Week 12
Change in Low-Density Lipoprotein Cholesterol Concentration	Fasting blood low-density lipoprotein (LDL) cholesterol concentration will be measured at baseline and each post-baseline assessment. Change from baseline will be calculated as the post-baseline concentration minus the baseline concentration and reported in milligrams per deciliter (mg/dL).	Baseline, Week 4, Week 8, and Week 12
Change in High-Density Lipoprotein Cholesterol Concentration	Fasting blood high-density lipoprotein (HDL) cholesterol concentration will be measured at baseline and each post-baseline assessment. Change from baseline will be calculated as the post-baseline concentration minus the baseline concentration and reported in milligrams per deciliter (mg/dL).	Baseline, Week 4, Week 8, and Week 12
Change in Triglyceride Concentration	Fasting blood triglyceride concentration will be measured at baseline and each post-baseline assessment. Change from baseline will be calculated as the post-baseline concentration minus the baseline concentration and reported in milligrams per deciliter (mg/dL).	Baseline, Week 4, Week 8, and Week 12
Change in Apolipoprotein B Concentration	Fasting blood apolipoprotein B (ApoB) concentration will be measured at baseline and each post-baseline assessment. Change from baseline will be calculated as the post-baseline concentration minus the baseline concentration and reported in milligrams per deciliter (mg/dL).	Baseline, Week 4, Week 8, and Week 12
Change in Apolipoprotein A-I Concentration	Fasting blood apolipoprotein A-I (ApoA-I) concentration will be measured at baseline and each post-baseline assessment. Change from baseline will be calculated as the post-baseline concentration minus the baseline concentration and reported in milligrams per deciliter (mg/dL).	Baseline, Week 4, Week 8, and Week 12
Change in Lipoprotein(a) Concentration	Fasting blood lipoprotein(a) concentration will be measured at baseline and each post-baseline assessment. Change from baseline will be calculated as the post-baseline concentration minus the baseline concentration and reported in nanomoles per liter (nmol/L).	Baseline, Week 4, Week 8, and Week 12
Change in Blood Glucose Concentration	Fasting blood glucose concentration will be measured at baseline and each post-baseline assessment. Change from baseline will be calculated as the post-baseline concentration minus the baseline concentration and reported in milligrams per deciliter (mg/dL).	Baseline, Week 4, Week 8, and Week 12.
Change in Blood Urea Nitrogen	Blood urea nitrogen (BUN) will be measured at baseline and each post-baseline assessment. Change from baseline will be calculated as the post-baseline value minus the baseline value and reported in milligrams per deciliter (mg/dL).	Baseline, Week 4, Week 8, and Week 12.
Change in Blood Creatinine Concentration	Blood creatinine concentration will be measured at baseline and each post-baseline assessment. Change from baseline will be calculated as the post-baseline concentration minus the baseline concentration and reported in milligrams per deciliter (mg/dL).	Baseline, Week 4, Week 8, and Week 12.
Change in Blood Sodium Concentration	Blood sodium concentration will be measured at baseline and each post-baseline assessment. Change from baseline will be calculated as the post-baseline concentration minus the baseline concentration and reported in millimoles per liter (mmol/L).	Baseline, Week 4, Week 8, and Week 12.
Change in Blood Potassium Concentration	Blood potassium concentration will be measured at baseline and each post-baseline assessment. Change from baseline will be calculated as the post-baseline concentration minus the baseline concentration and reported in millimoles per liter (mmol/L).	Baseline, Week 4, Week 8, and Week 12.
Change in Blood Chloride Concentration	Blood chloride concentration will be measured at baseline and each post-baseline assessment. Change from baseline will be calculated as the post-baseline concentration minus the baseline concentration and reported in millimoles per liter (mmol/L).	Baseline, Week 4, Week 8, and Week 12.
Change in Blood Carbon Dioxide Concentration	Blood total carbon dioxide, reflecting serum bicarbonate, will be measured at baseline and each post-baseline assessment. Change from baseline will be calculated as the post-baseline concentration minus the baseline concentration and reported in millimoles per liter (mmol/L).	Baseline, Week 4, Week 8, and Week 12.
Change in Blood Calcium Concentration	Blood calcium concentration will be measured at baseline and at each post-baseline assessment. Change from baseline will be calculated as the post-baseline concentration minus the baseline concentration and reported in milligrams per deciliter (mg/dL).	Baseline, Week 4, Week 8, and Week 12.
Change in Blood Total Protein Concentration	Blood total protein concentration will be measured at baseline and each post-baseline assessment. Change from baseline will be calculated as the post-baseline concentration minus the baseline concentration and reported in grams per deciliter (g/dL).	Baseline, Week 4, Week 8, and Week 12.
Change in Total Blood Albumin Concentration	Blood albumin concentration will be measured at baseline and at each post-baseline assessment. Change from baseline will be calculated as the post-baseline concentration minus the baseline concentration and reported in grams per deciliter (g/dL).	Baseline, Week 4, Week 8, and Week 12.
Change in Total Bilirubin Concentration	Blood total bilirubin concentration will be measured at baseline and each post-baseline assessment. Change from baseline will be calculated as the post-baseline concentration minus the baseline concentration and reported in milligrams per deciliter (mg/dL).	Baseline, Week 4, Week 8, and Week 12.
Change in Alkaline Phosphatase Activity	Blood alkaline phosphatase activity will be measured at baseline and each post-baseline assessment. Change from baseline will be calculated as the post-baseline value minus the baseline value and reported in units per liter (U/L).	Baseline, Week 4, Week 8, and Week 12.
Change in Alanine Aminotransferase Activity	Blood alanine aminotransferase (ALT) activity will be measured at baseline and each post-baseline assessment. Change from baseline will be calculated as the post-baseline value minus the baseline value and reported in units per liter (U/L).	Baseline, Week 4, Week 8, and Week 12.
Change in Aspartate Aminotransferase Activity	Blood aspartate aminotransferase (AST) activity will be measured at baseline and each post-baseline assessment. Change from baseline will be calculated as the post-baseline value minus the baseline value and reported in units per liter (U/L).	Baseline, Week 4, Week 8, and Week 12.
Change in Complete Blood Count With Differential	Changes in hematologic measures obtained from complete blood count with differential testing.	Baseline, Week 4, Week 8, and Week 12.
Change in Angina Burden and Disease-Specific Quality of Life	The Seattle Angina Questionnaire (SAQ) is a validated disease-specific patient-reported outcome measure for patients with angina and ischemic heart disease. The SAQ will be used to assess changes in angina burden and disease-specific quality of life during the 12-week plant-based dietary intervention. Higher scores indicate better health status and fewer angina-related limitations.	Baseline, Week 4, Week 8, and Week 12.
Change in Body Weight	Body weight measured during study visits and home monitoring to evaluate weight stability during the intervention.	Baseline, Week 4, Week 8, and Week 12.
Change in Blood Pressure	Blood pressure measured during study visits and through home monitoring to assess hemodynamic response to the dietary intervention	Baseline, Week 4, Week 8, and Week 12.

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Percentage of Prescribed Study Foods Consumed Assessed by ASA24 Dietary Recalls	Dietary adherence will be quantified using repeated Automated Self-Administered 24-Hour Dietary Assessment Tool (ASA24) recalls. Adherence will be calculated as the proportion of prescribed study foods reported as consumed relative to the foods assigned, expressed as a percentage. Possible values range from 0% to 100%, with higher percentages indicating greater adherence. Average adherence of at least 85% will define adherence for sensitivity analyses.	Day 0 through Week 12
Number of Participants With Animal-Food DNA Detected by FoodSEQ	FoodSEQ will be performed on a randomly selected subset of stool specimens to determine whether animal-food-derived DNA is detected. The outcome will be reported as the number of participants with animal-food-derived DNA detected in at least one evaluable specimen. A lower number indicates greater biological corroboration of adherence to the prescribed plant-based diet.	Day 0 through Week 12
Number of Participants Who Complete the 12-Week Intervention	The outcome will be reported as the number of enrolled participants who remain in the study through the end of the 12-week dietary intervention and complete the Week 12 assessment. Participants who withdraw before completing the intervention will not be counted as completers.	Week 12.

Collaborators and Investigators

• Sponsor: Emory University
• Collaborators: National Heart, Lung, and Blood Institute (NHLBI)
• Investigators: Principal Investigator: Rami Najjar, PhD, Emory University

Study record dates

Study Major Dates

• Study Start (Estimated): October 1, 2026
• Primary Completion (Estimated): January 1, 2028
• Study Completion (Estimated): January 1, 2028

Study Registration Dates

• First Submitted: August 31, 2026
• First Submitted That Met QC Criteria: September 9, 2026
• First Posted (Actual): September 15, 2026

Study Record Updates

• Last Update Posted (Actual): September 15, 2026
• Last Update Submitted That Met QC Criteria: September 9, 2026
• Last Verified: September 1, 2026

More Information

Terms related to this study

• Keywords: Coronary Microvascular Dysfunction; Plant-Based Diet; Flow-Mediated Dilation
• Other Study ID Numbers: 2026P001377; 1K99HL181306-01A1 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: De-identified individual participant data underlying the results reported from this study will be shared with qualified researchers through a controlled-access process after publication of the primary results. Shared data may include relevant demographic, clinical, dietary, vascular-function, laboratory, and derived molecular or microbiome data, together with a data dictionary and study protocol, as appropriate. Access will require a scientifically sound proposal, an executed data use agreement, and any applicable institutional or IRB approvals. Sharing will be limited to uses permitted by participant consent and applicable privacy, ethical, legal, and institutional requirements. Direct identifiers will not be shared. Data presenting an unacceptable risk of re-identification, including certain raw genomic or metagenomic files, may be withheld or subject to additional access restrictions.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No