The Dietary Guidelines 3 Diets Study (DG3D)

Ensuring the Cultural Relevance of Dietary Guidelines Diet Patterns Among African Americans: Increasing Dietary Quality and Reducing Type 2 Diabetes Risk

The goal of this project is to use a two-stepped study to examine both the adoption of the three dietary patterns as presented by the United States Dietary Guidelines (USDG) and testing of a refined, culturally tailored one-year intervention examining the three diet patterns. For this study, African American adult participants with overweight/obesity and ≥three type 2 diabetes (T2DM) risk factors will be recruited to participate in this two-step study. This present study is for our Step 1: formative pilot work to culturally-tailor a dietary intervention of the three healthy eating patterns presented by the USDG for 12 weeks: 1) U.S.-Style, 2) Mediterranean, or 3) Vegetarian.

Study Overview

• Status: Completed
• Conditions: Type 2 Diabetes
• Intervention / Treatment: Behavioral: Dietary Intervention Meetings

Detailed Description

The U.S. Dietary Guidelines (USDG) form the basis of federal nutrition programs and policy and provide valuable guidance to health initiatives and industries. The updated 2015 USDG moved away from a focus on individual nutrients to a greater focus on dietary patterns. The USDG state that healthy eating goals can be met through a variety of dietary patterns, but present healthy diet in three main ways: 1) Healthy U.S.-Style Eating Pattern, 2) Healthy Mediterranean-Style Eating Pattern, and 3) Healthy Vegetarian Eating Pattern. Currently, US adults are falling short of the nutrition recommendations (fruit/vegetable intake, greens/beans, whole grains, etc.) set forth by the USDG and measured by the Healthy Eating Index (HEI). While the USDG are the basis of nutrition guidelines, the research informing these dietary pattern recommendations has largely been drawn from observational studies among mostly white populations. In addition, there has been very limited cultural tailoring of these dietary patterns that would ensure that these diets are acceptable to diverse populations, in particular, African Americans (AAs) living in the south, who experience a disproportionate burden of chronic disease, especially type 2 diabetes (T2DM). Currently, US adults are not meeting nutrition recommendations (fruit/vegetable, whole grains, etc.) set forth by the USDG and measured by the Healthy Eating Index (HEI).

For the present study, AA adult participants with overweight/obesity and ≥three T2DM risk factors will be recruited to participate in the following aims:

Aim 1: Conduct a 3-month randomized trial among AAs comparing adoption of the 3 dietary patterns [1) US, 2) Med, or 3) Veg] using existing materials from the USDG and examine differences in diet quality (HEI) and T2DM risk factors (weight, HgbA1c).

Aim 2: Drawing on participants' experiences in Aim 1, conduct qualitative work to refine and culturally tailor the dietary pattern intervention for an AA audience.

• Study Type: Interventional
• Enrollment (Actual): 63
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • South Carolina
    • Columbia, South Carolina, United States, 29208
      • University of South Carolina

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• 18-65 years of age
• BMI between 25- 49.9 kg/m2
• self-identify as African American
• live in the Columbia, SC area
• be able to attend all monitoring visits
• be willing to be randomized to either condition and be re-randomized if non-responsive
• be free of major health or psychiatric diseases, drug or alcohol dependency, thyroid conditions, diabetes, or pregnancy

Exclusion Criteria:

• should not be pregnant (or have been pregnant in the last 6 months), anticipating on becoming pregnant in the next 24 months, or currently breastfeeding

  o Women who are pregnant should not be pursuing weight loss and should be under the direct care of a physician. Therefore women who are pregnant or who are anticipating they might be pregnant should not participate in this study. If a woman becomes pregnant during the study, she will be advised to consult with her healthcare provider and will be dropped from the weight loss study.

• should be free of an eating disorder as screened by the Eating disorder Screen for Primary care [ESP]. (If a participant has an eating disorder, they will be given contact information for the eating disorder clinic at the University of South Carolina)
• no current participation in a weight loss program or taking weight loss medications (although participants may be trying to lose weight on their own)
• no recent or planned bariatric surgery
• no recent weight loss (>10 lbs in the last 6 months)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: US Healthy Diet; Participants in this group will be assigned to follow the Healthy US dietary pattern as presented by the US Dietary Guidelines. As described here https://www.nia.nih.gov/health/usda-food-patterns: This eating pattern is based on the types and amounts of foods Americans typically consume. The main types of food in this eating pattern include a variety of vegetables; fruits; whole grains; fat-free or low-fat dairy; seafood, poultry, meat, and eggs; and nuts, seeds, and soy products.	Behavioral: Dietary Intervention Meetings; Participants will attend classes once per week for 3 months.
Experimental: Vegetarian diet; Participants in this group will be assigned to follow the Vegetarian dietary pattern as presented by the US Dietary Guidelines. As described here https://www.nia.nih.gov/health/usda-food-patterns: This eating pattern contains no meat, poultry, or seafood. Compared with the Healthy U.S.-Style Eating Pattern, it contains more soy products, eggs, beans and peas, nuts and seeds, and whole grains.	Behavioral: Dietary Intervention Meetings; Participants will attend classes once per week for 3 months.
Experimental: Mediterranean diet; Participants in this group will be assigned to follow the Mediterranean dietary pattern as presented by the US Dietary Guidelines. As described here https://www.nia.nih.gov/health/usda-food-patterns: This eating pattern contains more fruits and seafood and less dairy than the Healthy U.S.-Style Eating Pattern. There is also less calcium and vitamin D because it includes fewer dairy foods.	Behavioral: Dietary Intervention Meetings; Participants will attend classes once per week for 3 months.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Dietary quality	Dietary quality as assessed by the Healthy Eating Index	3 months
Body weight	Changes in body weight	3 months
Hemoglobin A1c	Changes in HgbA1c over 3 months	3 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Blood pressure	changes in systolic and diastolic blood pressure over 3 months	3 months

Collaborators and Investigators

• Sponsor: University of South Carolina

Publications and helpful links

General Publications

• Turner-McGrievy G, Wirth MD, Okpara N, Jones M, Kim Y, Wilcox S, Friedman DB, Sarzynski MA, Liese AD. Similar changes in diet quality indices, but not nutrients, among African American participants randomized to follow one of the three dietary patterns of the US Dietary Guidelines: A secondary analysis. Nutr Res. 2024 Nov;131:27-38. doi: 10.1016/j.nutres.2024.09.005. Epub 2024 Sep 7.
• Turner-McGrievy GM, Wilson MJ, Carswell J, Okpara N, Aydin H, Bailey S, Davey M, Hutto B, Wilcox S, Friedman DB, Sarzynski MA, Liese AD. A 12-Week Randomized Intervention Comparing the Healthy US, Mediterranean, and Vegetarian Dietary Patterns of the US Dietary Guidelines for Changes in Body Weight, Hemoglobin A1c, Blood Pressure, and Dietary Quality among African American Adults. J Nutr. 2023 Feb;153(2):579-587. doi: 10.1016/j.tjnut.2022.11.020. Epub 2022 Dec 23.

Study record dates

Study Major Dates

• Study Start (Actual): August 1, 2021
• Primary Completion (Actual): June 23, 2025
• Study Completion (Actual): June 23, 2025

Study Registration Dates

• First Submitted: July 27, 2021
• First Submitted That Met QC Criteria: July 27, 2021
• First Posted (Actual): July 29, 2021

Study Record Updates

• Last Update Posted (Actual): January 15, 2026
• Last Update Submitted That Met QC Criteria: January 13, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Endocrine System Diseases; Metabolic Diseases; Glucose Metabolism Disorders; Diabetes Mellitus; Nutritional and Metabolic Diseases; Diabetes Mellitus, Type 2
• Other Study ID Numbers: Pro00105836

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: To be determined

Drug and device information, study documents

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