What vitamins are missing in breast milk?

November 25, 2025 •

3 min read

While breast milk is often considered the perfect food for infants, studies show it doesn't provide adequate levels of all essential vitamins for a newborn. Understanding what vitamins are missing in breast milk is crucial for parents to ensure their baby's complete nutritional needs are met through appropriate supplementation.

Quick Summary

Breast milk is notably low in vitamins D and K, requiring supplementation for breastfed infants. Maternal diet can also impact levels of vitamins like B12, especially in vegan mothers.

Key Points

Vitamin D Supplementation: All breastfed infants require a daily 400 IU vitamin D supplement, as breast milk levels are consistently low and insufficient.
Vitamin K Injection: A one-time intramuscular vitamin K injection is administered to all newborns at birth to prevent a dangerous bleeding disorder, as breast milk contains very little vitamin K.
Maternal Diet and B12: The vitamin B12 content of breast milk is directly tied to the mother's dietary intake; vegan or vegetarian mothers are particularly at risk for deficiency and should supplement.
Iron Reserves: Full-term infants have sufficient iron stores for the first 4 to 6 months, after which supplementation may be recommended by a pediatrician.
Consult a Professional: Always consult a pediatrician before starting any supplements for your infant to ensure proper dosage and need.

Essential Vitamins to Supplement in Breastfed Infants

Breast milk is a dynamic and nutritionally complex fluid, perfectly tailored to a baby's needs for macronutrients like fat, carbohydrates, and protein. However, certain vitamins are consistently found in concentrations too low to meet an infant's full requirements, regardless of the mother's diet.

Vitamin D: The Sunshine Vitamin Gap

One of the most significant and well-documented vitamin deficiencies in breast milk is vitamin D. Even a well-nourished mother produces milk with insufficient levels. The American Academy of Pediatrics (AAP) recommends all breastfed and partially breastfed infants receive a daily 400 IU vitamin D supplement.

Vitamin K: Crucial for Blood Clotting

Vitamin K is another fat-soluble vitamin that is consistently low in breast milk. This deficiency can pose a serious and preventable risk to newborns. Low levels can lead to Vitamin K Deficiency Bleeding (VKDB). To prevent VKDB, a one-time intramuscular injection of vitamin K is administered to all newborns shortly after birth.

Vitamin B12: Maternal Diet is Key

Unlike vitamins D and K, the level of vitamin B12 in breast milk is directly influenced by the mother's nutritional status. Deficiency is a risk for mothers following a strict vegetarian or vegan diet. B12 deficiency in infants can cause anemia and neurological problems. Supplementation for at-risk mothers is crucial.

Comparison of Key Vitamin Needs


Nutrient	Requirement for Breastfed Infant	Recommendation for Breastfeeding Mother	Impact of Deficiency on Infant
Vitamin D	400 IU daily supplement, beginning shortly after birth.	Dependent on status; intake may not significantly raise breast milk levels to meet infant needs.	Rickets, weakened bones, impact on immune system.
Vitamin K	One-time intramuscular shot at birth.	Standard intake, no supplementation needed unless mother is deficient.	Vitamin K Deficiency Bleeding (VKDB).
Vitamin B12	Indirectly via mother's diet; supplementation needed if mother is at-risk.	2.8 mcg per day; higher for those with dietary restrictions or absorption issues.	Anemia, neurological problems, developmental delays.
Iron	Maternal iron stores adequate for first 4-6 months; supplementation from 4 months may be needed.	Dependent on diet; lower recommended daily intake than pregnancy due to lactational amenorrhea.	Anemia, impaired neurodevelopment.

Important Considerations for Parents

Other nutrients in breast milk also warrant attention. While water-soluble vitamins like folate and riboflavin can be influenced by maternal diet, a mother's body generally maintains sufficient levels unless there is severe malnutrition. Iron levels are also low, though highly bioavailable; supplementation around 4 months is often recommended. Zinc and calcium are largely unaffected by maternal intake. Vitamins A and E are usually sufficient, particularly in early colostrum.

Conclusion: Navigating Supplements Wisely

Breast milk is highly nutritious but lacks sufficient levels of certain key vitamins. Routine vitamin D supplementation and a vitamin K injection at birth are vital for the health of breastfed infants. Maternal diet significantly impacts B12 levels, especially for vegan mothers. Discussing supplementation needs, including iron around 4 months, with a pediatrician ensures optimal infant development.

For more detailed, science-backed guidance on infant nutrition, consult resources like the CDC's recommendations on {Link: Vitamin D and Breastfeeding https://www.cdc.gov/breastfeeding-special-circumstances/hcp/diet-micronutrients/vitamin-d.html}.

Summary of Common Breast Milk Deficiencies

Vitamin D: Breast milk contains insufficient levels of vitamin D, necessitating a daily 400 IU supplement for all breastfed infants to prevent rickets and bone development issues.
Vitamin K: Due to very low vitamin K content in breast milk and low neonatal stores, a one-time intramuscular injection at birth is standard to prevent life-threatening bleeding disorders.
Vitamin B12: Levels of vitamin B12 depend on maternal status, with vegan/vegetarian mothers at high risk of deficiency that can impact infant neurological development.
Iron: Infant iron stores are generally sufficient for the first several months, but supplementation around 4 months may be needed before introducing solid foods.
Maternal Diet Impact: A mother’s diet can influence the concentration of certain water-soluble vitamins in her breast milk, underscoring the importance of good maternal nutrition.

Frequently Asked Questions

No. While maternal diet and sun exposure can slightly influence breast milk's vitamin D content, it is not enough to meet an infant's needs. The AAP recommends direct supplementation for the baby regardless of the mother's diet.

Maternal vitamin K supplementation does not significantly increase the vitamin K content of breast milk. Furthermore, oral vitamin K is not reliably absorbed by infants, making the intramuscular injection the most effective way to prevent Vitamin K Deficiency Bleeding (VKDB).

If you are a vegan or strict vegetarian, you are at a higher risk of having insufficient B12 levels. This directly impacts the B12 content of your breast milk, and supplementation for both you and your baby may be necessary to prevent deficiency.

Full-term breastfed infants have sufficient iron stores for the first 4-6 months. However, the AAP recommends discussing iron supplementation with your pediatrician starting around four months, as your baby's reserves may be declining and growth is increasing.

A baby who doesn't get enough vitamin D is at risk for developing rickets, a disease that causes weak and softened bones. In severe cases, this can lead to bone deformities.

The concentration of water-soluble vitamins in breast milk is more dependent on the mother's dietary intake. For most healthy, well-nourished mothers, breast milk provides sufficient amounts. However, mothers with severe deficiencies may have lower levels.

No. The AAP recommends keeping infants under 6 months out of direct sunlight to prevent skin damage. Supplementation is the safest and most reliable way to ensure your baby receives adequate vitamin D.