Adherence to supplemental vitamin D intake and infant weight gain: a retrospective cohort study in rural southwestern China

OBJECTIVES: We tested the hypothesis that vitamin D supplementation is associated with early body mass index (BMI) patterns. METHODS: Using retrospective longitudinal data of infants and toddlers in a 2-year follow-up study, we identified BMI-for-age Z score (BAZ) growth trajectories using latent class growth modeling (LCGM) analysis. Logistic regression models were adopted to investigate the impact of vitamin D supplementation on BAZ patterns. RESULTS: Five BAZ trajectories were derived using LCGM. Higher intake of vitamin D supplement was significantly associated with lower odds of rapid weight gain or mild undernutrition in the first 2 years (odds ratios: 0.60–0.83 for class 2: early rapid growth; 0.69–0.82 for class 3: early weight loss, late rapid growth; 0.83–0.89 for class 4: suboptimal growth). Adherence to 400 IU Vitamin D ≥ 1 year was significantly associated with less likelihood of being in class 3 (odds ratio 0.17). CONCLUSIONS: Among infants and toddlers aged 0 to 2 years, dietary supplementation of vitamin D is insufficient in rural areas of China. Insufficient vitamin D intake was found to be associated with suboptimal BAZ growth at early stages. Effective collaboration is needed between pediatricians and caregivers, to assure adherence to the nutritional guideline.