Which Vitamin Is Not in Breastmilk? Understanding Infant Nutritional Needs

December 28, 2025 •

3 min read

Breastmilk provides a wealth of nutrients essential for infant growth and development, yet it does not supply adequate amounts of all vitamins. Health organizations highlight the importance of recognizing these specific nutritional gaps to ensure babies receive complete nourishment, often through recommended supplementation.

Quick Summary

Breastmilk contains low levels of vitamin D and K, necessitating supplementation for breastfed infants shortly after birth to support healthy development. Other vitamins, like B12, can also be impacted by maternal diet.

Key Points

Vitamin D Needs: Breastmilk typically contains low levels of vitamin D, making supplementation necessary for breastfed infants to support bone health.
Vitamin K Importance: Newborns have low vitamin K stores, and breastmilk is not a sufficient source, requiring preventive measures at birth to prevent dangerous bleeding.
Maternal Diet Influence: A mother's diet, especially if vegan, can impact breastmilk levels of certain vitamins, like B12, which are vital for infant development.
Professional Guidance: Pediatricians are the best resource for determining appropriate infant supplementation needs based on individual circumstances.
Formula vs. Breastmilk: Fortified formula generally contains higher levels of certain vitamins like D and iron compared to breastmilk, affecting supplementation needs.
Beyond Vitamins: Despite specific vitamin deficiencies, breastmilk offers unique immunological and digestive benefits.

Essential Vitamins and Deficiencies in Breastmilk

Breastmilk is widely recognized as the optimal source of nutrition for infants, offering a balanced composition of fats, proteins, carbohydrates, and most vitamins tailored to a baby's needs. However, there are specific vitamins where breastmilk concentrations are typically low, making supplementation a common recommendation from pediatric health experts. Understanding these particular nutritional aspects is vital for supporting a newborn's healthy start in life.

The Role of Vitamin D and Its Absence

Vitamin D is crucial for the absorption of calcium and phosphorus, minerals essential for the development of strong bones and teeth. Insufficient vitamin D intake in infants can lead to rickets, a condition characterized by soft, weakened bones. While sun exposure enables the skin to produce vitamin D, this method is not considered safe or appropriate for infants due to the risks of harmful UV radiation.

Variable Levels: The amount of vitamin D in breastmilk is largely dependent on the mother's own vitamin D status. Factors such as limited sun exposure, skin pigmentation, and dietary intake influence maternal levels. Standard maternal vitamin D intake often does not raise breastmilk levels sufficiently to meet the infant's requirements.
Standard Recommendations: Major health bodies, including the American Academy of Pediatrics, recommend vitamin D supplementation for breastfed and partially breastfed infants.

The Significance of Vitamin K

Vitamin K is essential for the process of blood clotting. Newborns are typically born with low levels of vitamin K because limited amounts transfer across the placenta. Breastmilk is not a rich source of this vitamin, which can leave infants vulnerable to a rare but serious condition called Vitamin K Deficiency Bleeding (VKDB), where excessive bleeding can occur.

Preventive Measures: To prevent VKDB, a vitamin K administration is a standard practice for all newborns shortly after birth. This is recommended for both breastfed and formula-fed infants.
Absorption Challenges: Oral administration of vitamin K is not always reliably absorbed by newborns, which is why other methods of delivery are often preferred for ensuring adequate levels.

Other Influencing Factors on Breastmilk Composition

Beyond vitamins D and K, other nutrients in breastmilk can be affected by the mother's nutritional status. For example, if a breastfeeding mother follows a strict vegan diet without supplementing, her breastmilk may be low in vitamin B12. Vitamin B12 is vital for neurological development in infants, and a deficiency can have serious health implications. In such instances, the mother may be advised to supplement, or in some cases, the infant may require direct supplementation.

Nutritional Needs Comparison: Breastfed vs. Formula-Fed Infants


Nutrient	Exclusively Breastfed Infant	Exclusively Formula-Fed Infant
Vitamin D	Supplementation is recommended.	Supplementation may not be needed if the formula is fortified and consumed in sufficient quantities.
Vitamin K	Administration is a standard recommendation at birth.	Administration is a standard recommendation at birth.
Iron	May require supplementation, particularly after four months, until iron-rich solids are consistently introduced.	Formula is typically iron-fortified, and supplementation is generally not needed.
Vitamin B12	Levels can be affected by maternal diet, potentially requiring maternal or infant supplementation if the mother has low levels.	Fortified formula usually provides adequate B12, though prenatal maternal levels are also important.

Conclusion: Ensuring Complete Infant Nutrition

While breastmilk offers unparalleled benefits for infants, including crucial antibodies and easily digestible nutrients, it is not a complete source of all essential vitamins, specifically vitamin D and K. Supplementation plays a key role in bridging these nutritional gaps to protect against conditions like rickets and VKDB. Consulting with a pediatrician is essential to develop an appropriate nutritional strategy for your baby, which may include specific vitamin supplements. By being informed about which vitamin is not adequately supplied in breastmilk and following professional advice, parents can help ensure their infant receives comprehensive nutrition for healthy growth and development.

For additional information on vitamin D and breastfeeding guidelines, consider visiting the CDC website.

Frequently Asked Questions

Breastmilk is commonly low in vitamin D and vitamin K, leading to recommendations for supplementation in breastfed infants.

Yes, many health organizations recommend vitamin D supplementation for all breastfed infants to ensure they receive adequate amounts for bone growth.

Newborns are born with insufficient vitamin K, and breastmilk is not a significant source, posing a risk of bleeding. A preventive measure at birth helps protect against this.

Direct sun exposure is not a recommended source of vitamin D for infants due to skin safety concerns. Supplementation is considered the safest method.

Inadequate vitamin D can lead to rickets, a condition that causes bones to become soft and potentially deformed.

A vegan mother should ensure adequate vitamin B12 intake through fortified foods or supplements to prevent deficiency in her breastmilk and protect her infant's neurological health.

Guidelines often suggest continuing vitamin D supplementation for breastfed infants until they reach one year of age or transition to fortified milk.

Breastfed infants usually have sufficient iron stores initially but may require iron supplementation starting around four months of age until they are consistently consuming iron-rich solid foods.