Breast Milk Contains Over 700 Bacteria Species - News & Features

30 July 2017
Breast Milk Contains Over 700 Bacteria Species

The debates around breastfeeding look set to continue for years to come, but there’s no disputing the fact that it’s highly nutritious for infants.

While some feel that feeding a baby in public is tantamount to a scandal, rather than a beautiful and biologically beneficial aspect of human nature, Spanish researchers have chosen to focus on the details that count. They discovered, on average, women’s breast milk contains about 700 bacterial species.

Charting the unknown

It’s been understood for some time that breastfeeding is one of the primary ways that infants experience contact with beneficial microorganisms. Prior to this study, the range of species found in breast milk was largely unknown. Researchers also hope to better understand the roles of the bacteria present.

This study examined the breast milk of 18 different mothers during three different time periods; the first excretion of the mammary glands following the baby's birth- known as colostrum, a month after the baby’s birth and six months later.

DNA details

"This is one of the first studies to document such diversity using the pyrosequencing technique (a large scale DNA sequencing determination technique) on colostrum samples on the one hand, and breast milk on the other, the latter being collected after one and six months of breastfeeding," explain the co-authors, María Carmen Collado, researcher at the Institute of Agrochemistry and Food Technology (IATA-CSIC) and Alex Mira, researcher at the Higher Public Health Research Centre (CSISP-GVA).

They found 700 species residing in the colostrum, most commonly Weissella, Leuconostoc, Staphylococcus, Streptococcus and Lactococcus. As the babies became older, the bacterial species present changed. Veillonella, Leptotrichia and Prevotella which are typically found in the oral cavity become increasingly common over time.

Further questions

"We are not yet able to determine if these bacteria colonize the mouth of the baby or whether oral bacteria of the breast-fed baby enter the breast milk and thus change its composition," researchers María Carmen Collado of the Institute of Agrochemistry and Food Technology and Alex Mira of the Higher Public Health Research Center, both in Spain, said in a statement.

Among other findings of the study, a less diverse microflora was found in the breast milk of overweight mothers or those who gained more weight than recommended during pregnancy.

The results also indicated that the hormonal state of the mother at the time of labour plays a role: "The lack of signals of physiological stress, as well as hormonal signals specific to labour, could influence the microbial composition and diversity of breast milk," state the authors.

Immune or metabolic?

The research also showed that mothers who had planned caesareans contained a lower diversity of bacteria species compared with those of other mothers. However, an emergency caesarean birth (intrapartum) showed breast milk composition that was very similar to that of mothers who experienced a vaginal birth.

The results could prove crucial for the design of child nutrition strategies that improve health."If the breast milk bacteria discovered in this study were important for the development of the immune system, its addition to infant formula could decrease the risk of allergies, asthma and autoimmune diseases," the researchers added.