Effects of vitamin D supplementation in infancy on growth, bone parameters, body composition and gross motor development at age 3-6 years: follow-up of a randomized controlled trial.

Background: The long-term effects of infant vitamin D supplementation and status are unclear since there have been few controlled intervention trials and these have been small and contradictory. The Delhi Infant Vitamin D Supplementation (DIVIDS) trial found that supplementation of low-birthweight term infants with one recommended dietary allowance of vitamin D from 1 week to 6 months of age resulted in increased length and weight at 6 months. In the DIVIDS-2 study we followed up the DIVIDS children, now aged 3-6 years, to determine longer-term effects.

Methods: DIVIDS children, 446 from the vitamin D arm and 466 from the placebo arm, attended the follow-up visit. Data collection included anthropometry, blood pressure, bone structure and strength by quantitative ultrasound (QUS), gross motor tests, deuterium dilution test of body composition on a subset (n = 229) and blood samples for measurement of vitamin D status.

Results: Body mass index Z scores (BMIZ) were lower (adjusted P = 0.003)in the vitamin D Group [-1.18 (SD 0.92)] when compared with the placebo [-1.02 (SD 0.91)] group as a result of slightly lower weight and slightly greater height. The vitamin D group also had lower thigh circumference and arm muscle area and borderline lower mid-upper arm circumference. There were no group differences in body fat percentage, bone QUS or blood pressure and few differences in motor development measures.

Conclusions: Vitamin D supplementation of low-birthweight infants in infancy resulted in children being thinner at age 3-6 years but in no differences in functional outcomes.