Lactoferrin (LF) is the most abundant glycoprotein in breast milk with antimicrobial and anti-inflammatory properties.1,2 Secretory IgA (SIgA) has also been identified as the most abundant and relevant breast milk antibody that can neutralize (bind and eliminate) bacterial and viral pathogens in the neonatal gastrointestinal tract.3,4 Ingestion of breast milk LF and SIgA help to protect the infants against microbial infections until their immature immune systems are completely developed at 2 years of postnatal age.5,6
The aim of this study was to determine the range of lactoferrin and SIgA concentrations between breast milk samples from a large population of mothers.
Breast milk samples (n = 180) were collected from 90 mothers between 2 and 13 months of lactation, living in the USA. SIgA and LF concentrations were determined by ELISAs.
LF and SIgA concentration varied widely in breast milk samples between mothers (Figure 1), which could be due to different maternal background (vaccinations, previous infections, and health conditions), nutritional and environmental factors, genetic factors, gut microbiota, and other factors influencing the immune systems.
The differences between the highest and the lowest concentrations of LF and SIgA in breast milk samples were 41.5-fold and 55-fold, respectively (Table 1 and Figure 1). During commercial sterilization (retort) of donor milk, SIgA and lactoferrin concentrations are reduced ~1.5- and 2.3-fold, respectively, compared with raw breast milk.7 The mean LF and SIgA resulting after donor milk is mixed with 50% raw breast milk mean is approximately 0.85 mg/mL and 204 µg/mL, both values are within the median/mean range of raw breast milk (Table 1).
Table 1. Concentration of lactoferrin and secretory IgA (SIgA) in raw breast milk samples (n = 180) from 90 mothers at 2–13 months of lactation and in 50% Medolac donor milk mixed with 50% raw breast milk.
Figure 1. Concentration of (A) secretory IgA (SIgA) and (B) lactoferrin in breast milk samples (n = 180) collected from 90 mothers at 2–13 months of lactation time living in the USA. Boxplots represent min, max and median.
Preterm infants fed raw breast milk mixed with Medolac donor milk ingest volumes of LF and SIgA that are within the median/mean range. However, the dose required of LF and SIgA to induce a significant protective effect against pathogens and their toxins remains unknown. Studies are needed to determine the minimum effective dose in addition to important maternal factors that may influence the concentration of SIgA and LF in raw breast milk.
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2. Telang, S. Lactoferrin: A Critical Player in Neonatal Host Defense. Nutrients 2018, 10.
3. Mantis, N.J.; Rol, N.; Corthésy, B. Secretory IgA's complex roles in immunity and mucosal homeostasis in the gut. Mucosal immunology 2011, 4, 603.
4. Macpherson, A.J.; Hunziker, L.; McCoy, K.; Lamarre, A. IgA responses in the intestinal mucosa against pathogenic and non-pathogenic microorganisms. Microbes Infect. 2001, 3, 1021-1035.
5. Duijts, L.; Jaddoe, V.W.; Hofman, A.; Moll, H.A. Prolonged and exclusive breastfeeding reduces the risk of infectious diseases in infancy. Pediatrics 2010, peds. 2008-3256.
6. Goldman, A.S.; Garza, C.; Nichols, B.L.; Goldblum, R.M. Immunologic factors in human milk during the first year of lactation. J. Pediatr. 1982, 100, 563-567.
7. Meredith-Dennis, L., Xu, G., Goonatilleke, E., Lebrilla, C.B., Underwood, M.A. and Smilowitz, J.T. Composition and variation of macronutrients, immune proteins, and human milk oligosaccharides in human milk from nonprofit and commercial milk banks. Journal of Human Lactation 2017, 34, 120-129.
About the Author
Dr. Veronique Demers-Mathieu is the Senior Research Scientist in the department of Neonatal Immunology and Microbiology at Medolac Laboratories. She did 3-years of postdoctoral training in Neonatal Nutrition under Dr. Dallas at Oregon State University and earned her Ph.D. in Food Microbiology at Laval University. Her expertise focuses on the immune components (including antibodies, immune cells, cytokines, and bioactive proteins) from human milk that protect infants against infectious diseases.