Researchers at the Institute of Agrochemistry and Food Technology (IATA-CSIC) and the Higher Public Health Research Centre (CSISP-GVA) in Spain and colleagues are the first to identify the bacterial content of breast milk in a January 4, 2012, article in the American Journal of Clinical Nutrition.
Samples of the first secretion of the mammary glands after giving birth (colostrum) and breast milk taken after one and six months of breast feeding contained as many as 700 different species of bacteria.
The most common bacterial genera in the colostrum samples were Weissella, Leuconostoc, Staphylococcus, Streptococcus and Lactococcus. In the fluid developed between the first and sixth month of breastfeeding, bacteria typical of the oral cavity were observed, such as Veillonella, Leptotrichia and Prevotella. Babies do not have any gut bacteria at birth. One of the possible functions of bacteria in breast milk is the development of a stable gut microbiome that aids in digestion and establishes a healthy microbe system.
The researchers found that signals of physiological stress, as well as hormonal signals specific to labor, could influence the microbial composition and diversity of breast milk.
This is the reason that the milk of overweight mothers or those who put on more weight than recommended during pregnancy contains a lesser diversity of species and women who had planned cesarean births had a lower bacterial species variety in their milk. Unplanned cesarean births demonstrated the same microbial diversity as vaginal births.
The researchers hope to develop a means to add the microbial complement that is best for babies to formula to potentially decrease the risk of allergies, asthma and autoimmune diseases and to improve infant digestion.
The research was reviewed at the Alpha Galileo website the date of publication.
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