Predictors of vitamin D supplementation amongst infants in Ireland throughout the first year of life

Aim: To investigate predictors of compliance with the recommendation that all infants in Ireland are supplemented daily from birth to 12 months of age with 5 μg of vitamin D. Subjects and methods: A prospective observational study was conducted. Self-complete questionnaires recorded socio-demographic characteristics, health behaviours and supplementation practices for 158 mother-infant dyads at 4, 9 and 12 months post-partum. A 2-day food diary was also obtained on 12-month-old infants to examine the contribution of diet to vitamin D intakes. Results: At 4, 9 and 12 months of age, 57.6% (n = 91), 34.2% (n = 54) and 23.4% (n = 37) of infants, respectively, were supplemented as recommended. In multivariate analyses, receiving supplementation advice from health professionals in the early post-partum period was the most significant predictor of correctly supplementing 4-month-old [p < 0.01; odds ratio, OR: 61.94 (95% confidence interval, CI: 11.53–332.83)], 9-month-old [p < 0.01, OR: 10.30 (95% CI: 2.29–46.27)] and 12-month-old [p = 0.04, OR: 3.85 (95% CI: 1.05–14.08)] infants. Amongst 12 month olds, mean intakes from diet and supplementation combined (7.6 ± 4.7 μg/day) were suboptimal. Conclusion: Suboptimal vitamin D supplementation practices were evident throughout infancy. Dietary intakes of vitamin D did not compensate for suboptimal supplementation practices. Supplementation practices may improve if health professionals advocate safe supplementation during routine infant health checks.