Do Exclusively Breastfed Babies Need Vitamin D Supplements? (by dietetic intern Nicole LoSauro)
Ever wonder why your pediatrician recommends vitamin D drops for your breastfed baby? My dietetic intern, Nicole LoSauro, explains the reasoning here! Nicole is in her final stages of becoming a Registered Dietitian, which includes earning a Master’s degree and 1,200 hours of supervised practice. You can follow Nicole on Instagram at @dietitian.nicole2026.
Breast milk is widely considered the gold standard for infant nutrition. It contains the ideal balance of nutrients, antibodies, and bioactive compounds that support a baby’s growth and immune system. Because of this, many parents naturally wonder: if breast milk is “perfect,” why do exclusively breastfed babies often need vitamin D supplements?
The answer lies in how humans historically obtained vitamin D. Unlike many nutrients that come directly from food, vitamin D is primarily produced through sun exposure. In past generations, people spent far more time outdoors, allowing both mothers and babies to maintain healthier vitamin D levels naturally. Today, however, many adults are vitamin D deficient or insufficient due to indoor lifestyles, sunscreen use, skin pigmentation, geographic location, and limited dietary sources of vitamin D (Holick, 2007).
Although breast milk contains small amounts of vitamin D, the concentration is often not high enough to meet an infant’s daily needs — especially if the breastfeeding mother herself has low vitamin D levels. Research has shown that maternal vitamin D status directly affects the amount transferred through breast milk (Wagner & Greer, 2008). This is one reason why many healthcare organizations recommend supplementation for breastfed infants.
The American Academy of Pediatrics (AAP) recommends that all exclusively or partially breastfed infants receive 400 IU of vitamin D daily beginning shortly after birth (AAP, 2022). The concern is not that breast milk is inadequate overall, but rather that modern lifestyles have changed how much vitamin D both mothers and infants naturally receive from sunlight.
Vitamin D plays an essential role in calcium absorption and bone development. Severe deficiency in infants can lead to rickets, a condition that causes soft or weakened bones. Beyond bone health, vitamin D may also support immune function and overall development (NIH Office of Dietary Supplements, 2023). Some studies suggest that high-dose maternal vitamin D supplementation during breastfeeding may provide enough vitamin D through breast milk alone, potentially reducing the need for infant drops (Hollis et al., 2015). However, this approach should only be done under medical supervision, since vitamin D dosing must be carefully monitored.
Ultimately, vitamin D supplementation is not evidence that breast milk is “imperfect.” Rather, it reflects the realities of modern living and widespread vitamin D deficiency. Breastfeeding remains one of the healthiest choices for infants, and adding a small vitamin D supplement is simply one additional step to help support optimal growth and development.
References
American Academy of Pediatrics. (2022). Vitamin D recommendations for infants and children.
Hollis, B. W., et al. (2015). Maternal versus infant vitamin D supplementation during lactation. Pediatrics.
Holick, M. F. (2007). Vitamin D deficiency. New England Journal of Medicine.
National Institutes of Health Office of Dietary Supplements. (2023). Vitamin D Fact Sheet for Health Professionals.
Wagner, C. L., & Greer, F. R. (2008). Prevention of rickets and vitamin D deficiency in infants, children, and adolescents. Pediatrics.
