What is the recommended dose of vitamin D (International Units) for infants, including those who are breastfed, formula-fed, or at risk of deficiency due to dark skin or limited sun exposure?

Recommended Dose of Vitamin D in Infants

All infants should receive 400 IU of oral vitamin D daily starting at hospital discharge, regardless of whether they are breastfed or formula-fed, to prevent vitamin D deficiency and rickets. 1, 2

Standard Dosing by Feeding Method

Breastfed Infants

• Begin 400 IU/day at hospital discharge and continue throughout the breastfeeding period 1, 2
• This applies to all breastfed infants since breast milk contains insufficient vitamin D to meet infant needs 3, 4
• Do not wait until the first outpatient visit—supplementation must start at discharge 1

Formula-Fed Infants

• Provide 400 IU/day until the infant consistently consumes at least 28 ounces (approximately 840 mL) of vitamin D-fortified formula daily 1
• Most infants reach this intake threshold within the first 2 months of life 3
• Once consuming ≥28 ounces of formula daily, supplementation can be discontinued as formula provides adequate vitamin D 1

Mixed-Fed Infants

• Continue 400 IU/day supplementation until the infant reliably consumes at least 28 ounces of formula daily 1

Special Populations Requiring Modified Dosing

Infants at Higher Risk of Deficiency

• Infants with dark skin pigmentation should receive 600 IU/day rather than the standard 400 IU/day 5
• Infants with limited sun exposure, living at high latitudes, or born to mothers with vitamin D deficiency are at increased risk but the standard 400 IU/day dose remains appropriate 1, 5

Preterm Infants

• Preterm infants require 200-400 IU/day initially, with some guidelines suggesting up to 800-1,000 IU/day for extremely preterm infants 1, 2
• For preterm infants on parenteral nutrition, provide 200-1,000 IU/day (or 80-400 IU/kg/day) 6, 2

Alternative Supplementation Strategy

Maternal Supplementation Option

• Lactating mothers can take 6,400 IU/day of vitamin D, which provides adequate vitamin D to the breastfed infant through breast milk 1
• This approach may be preferred by some families who find direct infant supplementation challenging 3
• However, maternal supplementation at standard doses (400 IU/day) is insufficient—only high-dose maternal supplementation (≥4,000 IU/day) achieves infant vitamin D levels comparable to direct infant supplementation 4

Evidence Supporting Higher Doses

While 400 IU/day is the standard recommendation, emerging evidence suggests potential benefits of higher doses in certain populations:

• A 2022 trial from a low-middle income country found that 800 IU/day reduced vitamin D insufficiency by 50% compared to 400 IU/day in breastfed term infants, with no evidence of toxicity 7
• However, this study was conducted in a population at high risk of deficiency, and current guidelines have not yet incorporated these findings into routine recommendations 7
• Higher doses (>400 IU/day) have not been consistently shown to have specific clinical benefits for healthy infants in well-nourished populations 3

Safety Thresholds

Upper Tolerable Limits

• The maximum safe daily dose is 1,000 IU/day for infants 0-6 months and 1,500 IU/day for infants 7-12 months 8, 2
• Vitamin D toxicity is very uncommon but can occur with extremely concentrated high-dose preparations 3
• Avoid commercially available drops with extremely high concentrations that could lead to accidental overdosing 3

Formulation Selection

• Cholecalciferol (vitamin D3) is preferred over ergocalciferol (vitamin D2) due to higher bioavailability and efficacy 8, 2
• Vitamin D can be administered via standard drops, drops placed on the mother's breast, or dissolvable doses 3

Monitoring and Target Levels

• The target serum 25-OH vitamin D level is >20 ng/mL (50 nmol/L) for bone health 8, 2
• Routine testing of serum 25-OH vitamin D levels is not recommended for healthy term or preterm infants receiving standard supplementation 3
• Testing should be reserved for infants with malabsorption conditions, chronic kidney disease, or those on long-term parenteral nutrition 8, 2

Common Pitfalls to Avoid

• Do not delay supplementation until the first outpatient visit—begin at hospital discharge 1
• Do not assume formula-fed infants receive adequate vitamin D until they consistently consume ≥28 ounces daily 1
• Do not use low-dose maternal supplementation (e.g., 400 IU/day) as a substitute for direct infant supplementation, as it is insufficient 4
• Ensure adherence to the supplementation regimen, as inconsistent supplementation is a common cause of treatment failure 8