Vitamin D status and child health, growth, and neurodevelopment

Abstract

Background: Vitamin D deficiency is one of the most commonly under diagnosed micronutrient deficiencies in the world. Both animal and human studies suggest that vitamin D plays an important role in innate and adaptive immunity, erythropoietin, and neurodevelopment, in addition to its osteoblastic activities. Objectives: To estimate the associations between vitamin D status in early childhood and i) acute lower respiratory tract infections, clinical pneumonia, diarrhea, anemia, neurodevelopment, and physical growth in early childhood; ii) neurodevelopment and physical growth in school age. Methods: We used data from a randomized placebo-controlled trial among 1000 North Indian children 6-30 months of age and a follow-up study conducted when the children were between 6-9 years. A quantitative electrochemiluminescence-binding assay was used to measure the plasma concentration of vitamin D. We used multivariable regressions to examine the association between vitamin D status and episodes of acute lower respiratory tract infections (ALRIs), clinical pneumonia, diarrhea, hemoglobin, anemia, neurodevelopment, and growth. Results: The prevalence of vitamin D deficiency (<10 ng/mL) was 34.5% when the children were 6-30 months old. The risk of ALRIs (OR 1.26; 95% CI: 1.03 to 1.55) and moderate anemia (RR 1.58; 95% CI: 1.09 to 2.31) was significantly higher among vitamin D deficient children than among non-deficient children. There were no significant differences in any of the cognitive outcomes and linear growth between vitamin D deficient and non-deficient children either during early childhood or at school age. Conclusions: Our results imply that vitamin D is one of the critical micronutrients for the prevention of ALRIs and anemia during early childhood, but it has a negligible role in neurodevelopment and growth in this population. Consequences: The protective role of vitamin D on ALRIs and anemia needs to be confirmed in randomized controlled trials targeting vitamin D deficient children.