Baseline Diet Quality Indicators and 6-Month Changes in Iron and Vitamin A Biomarkers among Rural Ghanaian Adolescents: A Secondary Analysis of the Ten2Twenty-Ghana Trial

BACKGROUND:Evidence linking food-based diet quality indicators to micronutrient biomarkers during adolescence in rural sub-Saharan Africa remains limited. OBJECTIVES:To examine associations between baseline diet quality and 6-mo changes in hemoglobin (Hb), iron-related biomarkers, and vitamin A status among rural schoolgirls in northern Ghana. METHODS:This secondary analysis used data from the Ten2Twenty-Ghana randomized controlled trial, which included 300 girls aged 10 to 17 y from 19 schools. Dietary intake was assessed using a quantitative 24-h recall. Diet quality indicators included the Global Diet Quality Score (GDQS), Minimum Dietary Diversity for Women (MDD-W), and gram-weighted intakes of NOVA (food classification system based on the nature, extent, and purpose of food processing) food groups. Multilevel linear and modified Poisson regression models examined associations between diet quality indicators and biomarkers of iron and vitamin A status, adjusting for baseline biomarkers, inflammation, height-for-age and BMI-for-age z-scores, household factors, energy intake, treatment allocation, and school clustering. RESULTS:Participants had a mean age of 12.7 ± 1.9 y; mean GDQS was 20.4 ± 3.3, and mean MDD-W was 3.8 ± 1.2, with 29.5% achieving MDD-W ≥5. At baseline, 38% had anemia, including 6.2% with iron-deficiency anemia (IDA) and 2.7% with vitamin A deficiency (VAD). Higher intake of whole or minimally processed foods was positively associated with soluble transferrin receptor (sTfR) concentrations [β: 3.0%; 95% confidence interval (CI): 1.0%, 6.2%], whereas ultraprocessed food intake was negatively associated with sTfR concentrations (β: -3.9%; 95% CI: -5.8%, -1.0%). Higher GDQS, GDQS+ (positive submetric of the GDQS), and MDD-W scores were inversely associated with ferritin concentrations but not with Hb, sTfR, or vitamin A biomarkers. No significant associations were observed with anemia or with risk of VAD. CONCLUSIONS:Conventional diet quality indicators and processing-based dietary measures were associated with iron-related biomarkers, although associations differed by biomarker. These findings suggest that dietary diversity and food processing capture complementary dimensions of diet quality in rural Ghanaian adolescents. This trial was registered at clinicaltrials.gov as NCT03368053.