Baseline Diet Quality Indicators and Six-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 six-month changes in haemoglobin, 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 10-17 years 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-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 years; 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 anaemia, including 6.2% with iron-deficiency anaemia and 2.7% with vitamin A deficiency. Higher intake of whole or minimally processed foods was positively associated with soluble transferrin receptor concentrations (β = 3.0%; 95% CI: 1.0%, 6.2%), whereas ultra-processed food intake was negatively associated with soluble transferrin receptor concentrations (β = -3.9%; 95% CI: -5.8%, -1.0%). Higher GDQS, GDQS+, and MDD-W scores were inversely associated with ferritin concentrations but not with haemoglobin, soluble transferrin receptor, or vitamin A biomarkers. No significant associations were observed with anaemia or with risk of vitamin A deficiency. CONCLUSIONS: Conventional diet quality indicators and processing-based dietary measures were associated with iron-related biomarkers, although associations differed by biomarker. These findings suggest dietary diversity and food processing capture complementary dimensions of diet quality in rural Ghanaian adolescents. Trial Registration ClinicalTrials.gov Identifier: NCT03368053 Registration URL: https://clinicaltrials.gov/study/NCT03368053.