Temporal Changes of Protein Composition in Breast Milk of Chinese Urban Mothers and Impact of Caesarean Section Delivery
Affolter M, Garcia-Rodenas CL, Vinyes-Pares G, Jenni R, Roggero I, Avanti-Nigro O, de Castro CA, Zhao A, Zhang Y, Wang P, Thakkar SK, Favre L
In addition to providing amino acids for growth, breast milk protein also has immunologically active molecules that confer passive immunity, stimulate antimicrobial defenses and promote immune maturation. The most abundant proteins in breast milk are lactoferrin, α-lactalbulmin, serum albumin and the β and κ casein fractions, which represent about 85% of total protein, while immune factors like IgA, IgM, IgG, TGFβ1 and TGFβ2 represent about 10%. Infants born by C-section had greater risk of developing immune-related diseases and this has been attributed to altered microbiota colonization, but altered immune factors in breast milk may also contribute. Therefore, this work assessed the main changes in breast milk proteins and assessed the impact of delivery by C-section in the MING study, a cross sectional study that took place in China.
Both, α-lactalbulmin and lactoferrin concentrations showed a temporal pattern and were higher at early stages of lactation, while serum albumin concentrations were constant across lactation. Casein was higher in the samples taken between 12 day and 2 months and decreased thereafter. Immune factors changed according to the stage of lactation: concentrations of IgA and IgM were higher in early milk and then rapidly decreased reaching a plateau by 1 month; and TGFβ1 and TGFβ2 were higher at the beginning and then decreased. C-section did not seem to affect immune factors concentration.
Nutrients. 2016 Aug 17;8(8). pii: E504. doi: 10.3390/nu8080504.