Modifying Diet to Improve Gut Microbiome

Modifying Diet and the Gut Microbiota to Reduce Obesity and Health Disparities

The investigators will conduct a 2-arm randomized controlled pilot, feasibility feeding study in which 28 participants will be randomized to receive either a calorie-restricted Dietary Approaches to Stop Hypertension (DASH) diet or a calorie-restricted standard American diet provided by the study for 4 weeks. Participants will be non-Hispanic black or white, generally healthy females (14 black, 14 white). The investigators will collect fecal samples at multiple time points before, during, and after the dietary intervention to analyze for changes in the gut microbiota and functional-level metabolic products. This work will be led by an interdisciplinary team including expertise in bio-behavioral science, microbiology, nutrition science, bioinformatics, and biostatistics all with cross-cutting expertise in health disparities, prevention research, nutrition, the gut microbiota, inflammation and other biomarkers. The rationale for the proposed research is that once the interactions between race, diet, and the gut microbiota are more fully understood, targeted diet modifications may provide new and innovative approaches for the prevention and treatment of obesity and obesity-related diseases.

Study Overview

• Status: Not yet recruiting
• Conditions: Obesity
• Intervention / Treatment: Behavioral: DASH diet; Behavioral: standard American diet

• Study Type: Interventional
• Enrollment (Estimated): 28
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Tiffany L Carson, PhD; Phone Number: 813-745-4944; Email: Tiffany.Carson@moffitt.org

Study Locations

• United States
  • Florida
    • Tampa, Florida, United States, 33612
      • Moffit Cancer center
      • Principal Investigator: Tiffany Carson, PhD
      • Contact: Tiffany Carson, PhD; Phone Number: 813-745-4944; Email: Tiffany.Carson@moffitt.org

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• female
• non-Hispanic, black or white
• age 19-65 years
• BMI >= 30 kg/m^2
• able to visit Bionutrition Unit daily

Exclusion Criteria:

• gastrointestinal (GI) conditions i.e., irritable bowel, diverticulitis, peptic ulcers, Crohn's, GI cancers, and adenatomous polyps
• antibiotic or probiotic use in the previous 90 days
• tobacco use
• heavy alcohol consumption
• major medical conditions (e.g., renal disease, diabetes, cancer)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: DASH diet; calorie-restricted DASH diet (25% fat; 57% carbohydrate; 18% protein; 34 g fiber	Behavioral: DASH diet; brief description
Active Comparator: standard American diet; calorie-restricted standard American diet (35% fat; 51% carbohydrate; %15 protein; 14 g fiber	Behavioral: standard American diet; describe

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mean Weight Change of Participants	Weight change as measured by a scale in kilograms at multiple time points will be calculated and averaged.	Baseline to day 28
Mean Weight Change of Participants	Weight change as measured by a scale in kilograms at multiple time points will be calculated and averaged.	Day 28 to Day 42
Mean Weight Change of Participants	Weight change as measured by a scale in kilograms at multiple time points will be calculated and averaged.	Baseline to day 42
Diet-specific changes in secondary bile acid	The investigators will calculate changes in cholic acid in milligrams.	Baseline to day 28
Diet-specific changes in secondary bile acid	The investigators will calculate changes in cholic acid in milligrams.	day 28 to day 42
Diet-specific changes in secondary bile acid	The investigators will calculate changes in cholic acid in milligrams.	baseline to day 42
Diet-specific changes in inflammatory marker	The investigators will calculate changes in c-reactive protein in mg/L.	baseline to day 28
Diet-specific changes in inflammatory marker	The investigators will calculate changes in c-reactive protein in mg/L.	day 28 to day 42
Diet-specific changes in inflammatory marker	The investigators will calculate changes in c-reactive protein in mg/L.	baseline to day 42
Diet-specific changes in short chain fatty acids	The investigators will calculate changes in acetic acid in mmol/L	baseline to day 28
Diet-specific changes in short chain fatty acids	The investigators will calculate changes in acetic acid in mmol/L	day 28 to day 42
Diet-specific changes in short chain fatty acids	The investigators will calculate changes in acetic acid in mmol/L	baseline to day 42

Collaborators and Investigators

• Sponsor: H. Lee Moffitt Cancer Center and Research Institute
• Investigators: Principal Investigator: Tiffany L Carson, PhD, Moffitt Cancer Center

Study record dates

Study Major Dates

• Study Start (Estimated): July 1, 2026
• Primary Completion (Estimated): August 1, 2026
• Study Completion (Estimated): August 1, 2026

Study Registration Dates

• First Submitted: March 25, 2019
• First Submitted That Met QC Criteria: April 19, 2019
• First Posted (Actual): April 23, 2019

Study Record Updates

• Last Update Posted (Estimated): September 10, 2025
• Last Update Submitted That Met QC Criteria: September 9, 2025
• Last Verified: September 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Nutrition Disorders; Overnutrition; Body Weight; Overweight; Pathological Conditions, Signs and Symptoms; Nutritional and Metabolic Diseases; Signs and Symptoms; Obesity; Therapeutics; Diet, Food, and Nutrition; Physiological Phenomena; Nutritional Physiological Phenomena; Diet Therapy; Nutrition Therapy; Diet; Dietary Approaches To Stop Hypertension
• Other Study ID Numbers: IRB-300003207

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

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