Vitamin D for Infants

Every infant born in the developed world should receive vitamin D — via drops (breastfed), formula (formula-fed), or maternal high-dose supplementation that passes through breastmilk. Rickets in infants is preventable, and undiagnosed hypocalcaemic seizures still occur in exclusively breastfed babies without supplementation.

AAP dosing recommendation

• All breastfed and partially breastfed infants — 400 IU cholecalciferol/day from the first few days of life, continued as long as they take < 1 L (32 oz) of vitamin D-fortified formula per day.
• Formula-fed infants — no supplementation needed once they consistently drink 1 L (32 oz) of vitamin D-fortified formula per day (fortified at 400 IU/L).
• Continue through year 1 and beyond as diet transitions to solid food.

Why breastfed infants need drops

Breastmilk is the biologically superior food for most reasons, but has one historically low nutrient: vitamin D. A mother with normal 25(OH)D (around 30 ng/mL) supplies only ~25–50 IU/L in breastmilk — well short of the 400 IU/day infant target. Without supplementation, breastfed infants (especially with dark skin, in northern latitudes, or in winter) are at real risk of rickets.

The 6,400 IU maternal alternative

Wagner and Hollis's 2015 landmark trial showed that a breastfeeding mother taking 6,400 IU cholecalciferol/day transfers enough vitamin D via breastmilk that her infant achieves the same 25(OH)D as an infant on 400 IU/day of drops. This is a practical alternative for mothers who prefer taking a pill themselves over dosing the infant directly. It's safe with monitoring, and often more compliant.

Rickets — the preventable disease

Nutritional rickets is still occurring in high-income countries: exclusively breastfed infants of dark-skinned mothers, veiled women, and prolonged breastfeeding without supplementation are the classic scenarios. Presentation includes hypocalcaemic seizures in the first year, delayed milestones, bowed legs, rachitic rosary, craniotabes, and delayed fontanelle closure. All entirely preventable with 400 IU/day.

Practical dosing

• Products: D-Vi-Sol, Baby Ddrops (1 drop = 400 IU concentrated), Enfamil D drops.
• Give directly into the mouth, or onto the nipple before nursing, or in a small amount of expressed milk.
• Don't add to a full bottle — vitamin D drops may not disperse and the infant may not drink the full bottle.
• Overdose risk: concentrated drops (2,000 IU/drop products exist) require careful measurement — nine cases of infant hypercalcaemia reported from mis-dosed concentrated products in a 2019 review.