Breast Milk contains Beneficial Bacteria

The amount of beneficial bacteria in breast milk varies depending on the mode of delivery, gestational age at birth, and the lactation stage of the mother.

Breast milk is a complex mixture of nutrients that offers immunological protection through molecular and cellular components, such as:

  1. Antifungal and antibacterial proteins, like lactoferrin and lysozyme,
  2. Macrophages, white blood cells that are known to ingest foreign microbes,
  3. Antibodies from the mother that provide an infant with immunity to previously-encountered antigens.

However, breast milk also contains microorganisms that are key to the development of an infant’s immune system and digestion. (1, 2, 3) Individuals are host to a variety of microbial species and they are referred to collectively as human microbiota.

Breast Milk | The human body is colonized by a vast array of microbes, collectively referred to as the human microbiota. Microbiota is present in breast milk. (Credit: Nature)

The human body is colonized by a vast array of microbes, collectively referred to as the human microbiota. Microbiota is present in breast milk. (Credit: Nature)

Breast Milk | The human body is colonized by a vast array of microbes, collectively referred to as the human microbiota. Microbiota is present in breast milk. (Credit: Nature)

The human body is colonized by a vast array of microbes, collectively referred to as the human microbiota. Microbiota is present in breast milk. (Credit: Nature)

Breast Milk | The human body is colonized by a vast array of microbes, collectively referred to as the human microbiota. Microbiota is present in breast milk. (Credit: Nature)

The human body is colonized by a vast array of microbes, collectively referred to as the human microbiota. Microbiota is present in breast milk. (Credit: Nature)

Breast Milk | The human body is colonized by a vast array of microbes, collectively referred to as the human microbiota. Microbiota is present in breast milk. (Credit: Nature)

The human body is colonized by a vast array of microbes, collectively referred to as the human microbiota. Microbiota is present in breast milk. (Credit: Nature)

The microbiota present in breast milk have been shown to play a significant role in infant health. For example, low birth weight and preterm infants are less likely to develop sepsis when breastfed. Despite strong support for breastfeeding from the World Health Organization and American Academy of Pediatrics, the microbiota of breast milk remains largely uncharacterized. A complete characterization of breast milk would allow for a better understanding of future health outcomes and appropriate formula supplementation when breast milk is not available.

A recent study by researchers at the Department of Pediatrics at the University of Valencia, Spain investigates the influence of gestational age at birth, mode of delivery, and stage of lactation on human milk microbiota. They studied 96 milk samples from 32 healthy mothers who were recruited immediately after delivery at the Maternity Ward of the Hospital Clinico Universitario of Valencia, Spain. (5) Thirteen mothers had gestations at term/full term (equal to or greater than 37 weeks), and 19 had pre-term gestations (less than 37 weeks); fifteen had vaginal deliveries and 17 had Cesarean sections. Samples were collected throughout the first month of breastfeeding to identify microbial variability during the three different stages of lactation:

  1. Colostrum (day 1-5 post partum)
  2. Transitional (day 6-15),
  3. Mature (day 16 and beyond)

Their results highlight significant differences in microbial content over time. Total bacterial concentration was found to be lower in colostrum than in transitional or mature milk. Two strains in particular, Bifidobacterium spp and Enterococcus spp, showed lower levels in colostrum. The bacterial composition of milk from mothers who delivered pre-term was also found to differ significantly from mothers with full term births. For example, Bifidobacterium was found to be higher in milk from mothers who reached full term.

Breast Milk | Bifidobacterium Strains constitute nearly 95% of the bacterial community in the neonatals who have been fed with breast milk.

Bifidobacterium Strains constitute nearly 95% of the bacterial community in the neonatals who have been fed with breast milk.

Breast Milk | Bifidobacterium Strains constitute nearly 95% of the bacterial community in the neonatals who have been fed with breast milk.

Bifidobacterium Strains constitute nearly 95% of the bacterial community in the neonatals who have been fed with breast milk.

Breast Milk | Bifidobacterium Strains constitute nearly 95% of the bacterial community in the neonatals who have been fed with breast milk.

Bifidobacterium Strains constitute nearly 95% of the bacterial community in the neonatals who have been fed with breast milk.

Breast Milk | Bifidobacterium Strains constitute nearly 95% of the bacterial community in the neonatals who have been fed with breast milk.

Bifidobacterium Strains constitute nearly 95% of the bacterial community in the neonatals who have been fed with breast milk.

Their results also highlight differences in microbial content depending on the mode of delivery. In general, Cesarean births showed higher concentrations of bacteria in maternal colostrum and transitional milk. Specifically, Cesearean births were associated with higher concentrations of Streptococcus whereas vaginal births were associated with higher concentrations of Bifidobacterium.

Changes in the microbiota of infants may lead to a number of developmental consequences. (5) Variations in the bacterial composition of milk from mothers exposed to different conditions suggest that each bacterial species may play a unique role to suit infant needs. Previous studies suggest that fecal Bifidobacterium concentrations may be used as a biomarker for healthy, breastfed infants. (6) On the other hand, infants who are susceptible to infection may show a delay in intestinal colonization based on mode of delivery and associated changes in mothers’ breast milk.

Although several studies have noted differences in the intestinal microbiota of infants delivered by Cesarean versus vaginal birth, this is the first study to demonstrate that delivery affects the composition of maternal breast milk. Although this study demonstrates a clear association between particular bacterial species and maternal conditions, it does not provide a mechanism to explain the association. There is no clear explanation for how particular species of bacteria are concentrated in the mammary glad for transfer into breast milk.

Breast Milk | The microbiota composition of colostrum, transitional and mature milk contains various amounts of Bifidobacterium, Lactobacillus, Staphylococcus, Streptococcus and Enterococcus spp., which, consequently, may affect the infant’s early intestinal colonization.

The microbiota composition of colostrum, transitional and mature milk contains various amounts of Bifidobacterium, Lactobacillus, Staphylococcus, Streptococcus and Enterococcus spp., which, consequently, may affect the infant’s early intestinal colonization.

Breast Milk | The microbiota composition of colostrum, transitional and mature milk contains various amounts of Bifidobacterium, Lactobacillus, Staphylococcus, Streptococcus and Enterococcus spp., which, consequently, may affect the infant’s early intestinal colonization.

The microbiota composition of colostrum, transitional and mature milk contains various amounts of Bifidobacterium, Lactobacillus, Staphylococcus, Streptococcus and Enterococcus spp., which, consequently, may affect the infant’s early intestinal colonization.

Breast Milk | The microbiota composition of colostrum, transitional and mature milk contains various amounts of Bifidobacterium, Lactobacillus, Staphylococcus, Streptococcus and Enterococcus spp., which, consequently, may affect the infant’s early intestinal colonization.

The microbiota composition of colostrum, transitional and mature milk contains various amounts of Bifidobacterium, Lactobacillus, Staphylococcus, Streptococcus and Enterococcus spp., which, consequently, may affect the infant’s early intestinal colonization.

Breast Milk | The microbiota composition of colostrum, transitional and mature milk contains various amounts of Bifidobacterium, Lactobacillus, Staphylococcus, Streptococcus and Enterococcus spp., which, consequently, may affect the infant’s early intestinal colonization.

The microbiota composition of colostrum, transitional and mature milk contains various amounts of Bifidobacterium, Lactobacillus, Staphylococcus, Streptococcus and Enterococcus spp., which, consequently, may affect the infant’s early intestinal colonization.

References

  1. Walker, A. Breast milk as the gold standard for protective nutrients. J Pediatr 2010; 156: 3–7.
  2. Lönnerdal, B. Bioactive proteins in human milk: mechanisms of action. J Pediatr2010; 156: 26–30.
  3. Martín, R., Langa, S., Reviriego, C., Jiménez E., Marín, M.L., Xaus, J. et al. Human milk is a source of lactic acid bacteria for the infant gut. J Pediatr 2003; 143: 754–758.
  4. Patel, A.L., Johnson, T.J., Engstrom, J.L., Fogg, L.F., Jegier, B.J., Bigger, H.R. et al. Impact of early human milk on sepsis and health-care costs in very low birth weight infants. J Perinatol 2013
  5. Khodayar-Pardo, P., Mira-Pascual, L., Collado, M.C., Martinez-Costa, C. Impact of
    lactation stage, gestational age and mode of delivery on breast milk microbiota. J Perinitol 2014: 34, 599-605
  6. Grönlund, M.M., Gueimonde, M., Laitinen, K., Kociubinski, G., Grönroos, T., Salminen, S. et al. Maternal breast-milk and intestinal bifidobacteria guide the compositional development of the Bifidobacterium microbiota in infants at risk of allergic disease. Clin Exp Allergy 2007; 37: 1764–1772.
  7. Figure 1: Human microbiota [Nature].
  8. Figure 2: Bifidobacterium [Probiotics 101].
  9. Figure 3: Microbiota composition of colostrum, transitional and mature milk, analyzed by quantitative PCR. From Khodayar-Pardo, P., Mira-Pascual, L., Collado, M.C., Martinez-Costa, C. Impact of lactation stage, gestational age and mode of delivery on breast milk microbiota. J Perinitol 2014: 34, 599-605.

Juliesta Sylvester, Ph.D. is a biochemist who promotes innovation and technology transfer at the interface of academia and industry. Her research has spanned pharmaceutical discovery, molecular diagnostics, bioinformatics, and quantitative systems analysis. She is an avid world traveler, invited speaker at national and international meetings, and enthusiastic consultant for startups.

Juliesta Sylvester, Ph.D. is a biochemist who promotes innovation and technology transfer at the interface of academia and industry. Her research has spanned pharmaceutical discovery, molecular diagnostics, bioinformatics, and quantitative systems analysis. She is an avid world traveler, invited speaker at national and international meetings, and enthusiastic consultant for startups.

Juliesta Sylvester, Ph.D. is a biochemist who promotes innovation and technology transfer at the interface of academia and industry. Her research has spanned pharmaceutical discovery, molecular diagnostics, bioinformatics, and quantitative systems analysis. She is an avid world traveler, invited speaker at national and international meetings, and enthusiastic consultant for startups.

Juliesta Sylvester, Ph.D. is a biochemist who promotes innovation and technology transfer at the interface of academia and industry. Her research has spanned pharmaceutical discovery, molecular diagnostics, bioinformatics, and quantitative systems analysis. She is an avid world traveler, invited speaker at national and international meetings, and enthusiastic consultant for startups.

The Michelson Medical Research Foundation‘s Groundwork blog is brought to you thanks to the generous support of Dr. Gary K. Michelson and his wife, Alya Michelson.
The Michelson Medical Research Foundation‘s Groundwork blog is brought to you thanks to the generous support of Dr. Gary K. Michelson and his wife, Alya Michelson.
The Michelson Medical Research Foundation‘s Groundwork blog is brought to you thanks to the generous support of Dr. Gary K. Michelson and his wife, Alya Michelson.
The Michelson Medical Research Foundation‘s Groundwork blog is brought to you thanks to the generous support of Dr. Gary K. Michelson and his wife, Alya Michelson.