Breastfeeding improves baby immunity

Summary: Benefits of Breast Milk

August is National Breastfeeding Awareness Month

A paper published in Science on Aug. 14, 2025,(1) confirmed what we all knew: that breast milk is best for babies. It reported that the intake of maternal antibodies in the milk regulates the baby's gut immune response. This sets the basis for a stable and lifelong host-microbiome relationship, characterized by more efficient nutrient absorption, reduced inflammation, and a defense against pathogens.

Breastfeeding benefits proven

This study confirms that breast milk helps develop the infant's immune responses. The live microbes, sugars, maternal cells, and antibodies contained in breast milk act directly upon the lactating baby's gut.

This helps, according to the authors "boost healthy immunity in early life and beyond."

The study used mice and reported that antibodies in breast milk helped improve the response of certain immune cells, such as TFH and B cells. They also noticed a lower " susceptibility to colitis and prevent[ion of ]aberrant allergic responses to food antigens during the weaning transition."

Unfortunately, according to the Centers for Disease Control, in the US, breastfeeding rates are low: "among infants born in 2019 (83.2%) started out receiving some breast milk. At 1 month, 78.6% were receiving any breast milk. At 6 months, 55.8% of infants received any breast milk, and 24.9% received breast milk exclusively". So, an initial 17% of babies do not benefit from this immune-enhancing effect at birth, and the figure grows to 45% at six months.

References and Further Reading

(1) Meera K. Shenoy et al., (2025). Breast milk IgG engages the mouse neonatal immune system to instruct responses to gut antigens. Science389, eado5294. doi:10.1126/science.ado5294