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

The goal of this study was to examine the relationship between diet quality, nutrients, and health outcomes among participants in the Dietary Guidelines: 3 Diets study (3-group randomized 12-week intervention; African American; Southeastern virtual teaching kitchen). Participants (n = 63; ages 18-65 y, BMI 25-49.9 kg/m) were randomized to the Healthy U.S. (H-US), Mediterranean (Med), or Vegetarian (Veg) groups. Hypotheses tested included (1) that the more plant-based diet patterns (Veg and Med) would have greater improvements in all diet quality indices (Dietary Approaches to Stop Hypertension (DASH), Dietary Inflammatory Index (DII), alternate Mediterranean Diet Index (aMED), healthy Plant-based Dietary Index (hPDI) assessed via three dietary recalls) as compared to the H-US pattern and (2) that each index would separately predict changes in weight loss, hemoglobin A1c (HbA1c), and blood pressure (BP). None of the group-by-time interactions for any of the diet indices were significant. Compared to the H-US group, Veg participants had greater increases in fiber (difference between groups 5.72 ± 2.10 5 g/day; P = .01), riboflavin (0.38 ± 0.19 mg/day; P = .05), and folate (87.39 ± 40.36 mcg/day; P = .03). For every one-point increase in hPDI, there was a 1.62 ± 0.58 mmHg decrease in systolic BP, for every one-point increase in aMED there was a 1.45 ± 0.70 mmHg decrease in diastolic BP, and for every one-point increase in hPDI, there was a 1.15 ± 0.38 mmHg decrease in diastolic BP. Findings indicate that there is significant overlap in the dietary recommendations of the three dietary patterns presented in the USDG and similarities in how African American adults adopt those diet patterns. Clinical Trials registry at clinicaltrials.gov:NCT04981847.