400 IU of Vitamin D daily got only half of the infants to 30 ng/mL (might need 1,600 IU)
Vitamin D Supplementation and Serum 25-Hydroxyvitamin D Response in Infants and Children: A Narrative Review
Pediatric Health, Medicine and Therapeutics https://doi.org/10.2147/PHMT.S616777 Aug 2026
Simon Vieth, Ddrops Company, Toronto, ON, Canada
Correspondence: Simon Vieth, Ddrops Company, Toronto, ON, Canada, Email simon.vieth@ddrops.ca
Background: Vitamin D deficiency remains common among infants and young children, particularly in higher latitudes and among exclusively breast-fed infants. Although routine supplementation is widely recommended, variability in achieved serum 25- hydroxyvitamin D [25(OH)D] concentrations has been reported across pediatric populations. Understanding the consistency of biochemical response across diverse pediatric settings remains clinically relevant for both research and supplementation practice.
Objective: To summarize evidence from pediatric clinical studies utilizing a standardized vitamin D formulation and to assess the magnitude and consistency of serum 25(OH)D response across independent investigator-initiated studies.
Methods: Relevant studies were identified through company-supported research records and a supplementary PubMed search. Eligible publications were published between 2010 and 2020 and included infants or children <18 years receiving vitamin D supplementation with reported baseline and follow-up 25(OH)D concentrations. Studies were required to explicitly identify the study formulation and report serum 25(OH)D outcomes. A narrative synthesis approach was applied.
Results: Seven studies (Canada, Australia, Vietnam, and Mongolia; total n = 3,800) met inclusion criteria. Supplementation doses ranged from 400 IU/day to 14,000 IU/week across study durations of 1-12 months. Mean baseline 25(OH)D concentrations (=53 nmol/L) increased to =75 nmol/L (mean A =22 nmol/L). Daily supplementation at 400 IU achieved sufficiency in the majority of infants, while higher-dose regimens produced proportionally greater increases. No study reported clinically significant adverse events attributable to supplementation.
Conclusion: Vitamin D supplementation produced consistent and clinically meaningful increases in serum 25(OH)D concentrations across diverse pediatric populations. The approximately 20-25 nmol/L increase observed across the included studies was broadly consistent with published pediatric vitamin D supplementation literature. These findings support current supplementation practices while highlighting the reproducibility of biochemical response across independent pediatric research settings.
Related in VitaminDWiki
- Infant Vitamin D – JAMA said 1600 IU, Europe says 1,000 IU upper limit
- 1600 IU vitamin D safe for infants – RCT
- Infants receiving 1600 IU of vitamin D were safe and healthy – RCT
- 400 IU of vitamin D does not help infants much (no surprise)
- Virtually all infants in Poland got 400 IU of Vitamin D daily (not enough, non-daily is better)
- Vitamin D does not help children (if only use 400 IU of D3 or D2 or quarterly) – Cochrane
- Children need 2000 IU of Vitamin D (India) - RCT
Daily is not the best for children, elderly, etc