The Diet Guidelines: 3 Diets (DG3D) study protocol of a behavioral teaching kitchen intervention for type-2 diabetes prevention among African American adults

Abstract

Background: The U.S. Dietary Guidelines (USDG) serve as a foundational public health resource, yet their cultural applicability to underserved populations, including Black and African American (AA) adults, remains limited. The AA population is disproportionately affected by obesity and type 2 diabetes mellitus (T2DM), highlighting the need for culturally tailored interventions.

Objectives: To describe the design and methodology of the Dietary Guidelines: 3 Diets (DG3D) study, aimed at evaluating the effectiveness of culturally adapted USDG dietary patterns in improving diet quality and reducing risk factors associated with T2DM among AA adults. The intervention focuses on nutritional education and the promotion of healthy eating behaviors to support sustainable dietary change.

Methods: The DG3D study is a 12-month, single-masked, three-arm randomized behavioral nutrition intervention designed to evaluate three culturally adapted USDG dietary patterns: Healthy US, Mediterranean, and Vegetarian. The study recruited AA adults with overweight or obesity and at least three additional risk factors for T2DM. Participants were randomized to one of three dietary patterns and received group-based classes, cooking demonstrations, and web-based educational content. Primary outcomes include changes in diet quality (Healthy Eating Index [HEI]), body weight, and hemoglobin A1c (HbA1c), assessed at baseline, 6 months, and 12 months.

Conclusion: The DG3D study is a novel and comprehensive randomized trial evaluating culturally tailored dietary patterns in the AA population, a high-risk population. Findings are expected to inform inclusive dietary policy and contribute to reducing health disparities related to obesity and T2DM.

Trial registration: ClinicalTrials.gov identifier NCT05254496.

Keywords: African American; Dietary guidelines; Healthy eating index; Obesity; Randomized controlled trial; Teaching kitchen intervention; Type 2 diabetes prevention.