antibacterial properties of breast milk

Researchers have taken a closer look at the antibacterial properties of breast milk to find out what makes it so good for fighting infectious bacteria.

The beneficial properties of breast milk are well established: The World Health Organisation recommends that babies are exclusively breastfed until six months of age, and then alongside solid food, breastfeeding should continue ideally up to two years of age. Researchers from the University of Iowa and National Jewish Health took a closer look at one of the constituents of breast milk, glycerol monolaureate (GML), to see if it is partly responsible for the antibacterial properties of breast milk. Their results were published in the prestigious journal, Nature.

The researchers found that breast milk contains 200 times the amount of GML than cows’ milk does, and that infant formula contains none. When GML was removed from breast milk in the lab, it was found that the breast milk was unable to fight certain types of bacteria that can cause serious infections. However, when it was added back to the breast milk it was able to fight them again.

What makes GML really special though, is that unlike antibiotics, which kill all bacteria, good and bad, GML did not kill the good bacteria found in a baby’s gut. Patrick Schlievert, professor of microbiology and immunology at the University of Iowa Carver College of Medicine, and first author on the scientific publication of the results thinks that “GML holds great promise as a potential additive to cow’s milk and infant formula that could promote the health of babies around the world.”

In addition to the benefits of killing bad bacteria, GML also acts to decrease inflammation along the lining of the gut. Inflammation in this location can make babies more susceptible to disease. The authors discuss that the antibacterial effects of breast milk are unlikely to be due to GML acting alone. There must be an interplay of factors, some currently unknown that makes the properties of breast milk so special.


Written by Nicola Cribb, MA VetMB DVSc DipACVS



Schlievert P, Kilgore S, Seo K, et al. Glycerol Monolaurate Contributes to the Antimicrobial and Anti-inflammatory Activity of Human Milk. Nature. volume 9, Article number 14550 (2019).

EurekAlert! Compound in Breast milk fights harmful bacteria. Last accessed October 11, 2019.

Image by Iuliia Bondarenko from Pixabay

Facebook Comments