The human milk microbiota, also known as human milk probiotics (HMP), encompasses the microbiota–the community of microorganisms–present within the human mammary glands and breast milk. Contrary to the traditional belief that human breast milk is sterile, advancements in both microbial culture and culture-independent methods have confirmed that human milk harbors diverse communities of bacteria. These communities are distinct in composition from other microbial populations found within the human body which constitute the human microbiome.
The microbiota in human milk serves as a potential source of commensal, mutualistic, and potentially probiotic bacteria for the infant gut microbiota. The World Health Organization (WHO) defines probiotics as "living organisms which, when administered in adequate amounts, confer a health benefit on the host."
