Effect of maternal prebiotic supplementation on human milk immunological composition: Insights from the SYMBA study

Background: Immunomodulatory proteins in human milk (HM) can shape infant immune development. However, strategies to modulate their levels are currently unknown. This study investigated whether maternal prebiotic supplementation alters the levels of immunomodulatory proteins in HM. Methods: The study was nested within the SYMBA double-blind randomized controlled trial (ACTRN12615001075572), which investigated the effects of maternal prebiotic (short-chain galacto-oligosaccharides/long-chain fructo-oligosaccharides) supplementation from <21 weeks gestation during pregnancy until 6 months postnatal during lactation on child allergic disease risk. Mother–child dyads receiving prebiotics (n = 46) or placebo (n = 54) were included in this study. We measured the levels of 24 immunomodulatory proteins in HM collected at 2, 4, and 6 months. Results: Cluster analysis showed that the overall immunomodulatory protein composition of milk samples from both groups was similar. At 2 months, HM of prebiotic-supplemented women had decreased levels of TGF-β1 and TSLP (95% CI: −17.4 [−29.68, −2.28] and −57.32 [−94.22, −4.7] respectively) and increased levels of sCD14 (95% CI: 1.81 [0.17, 3.71]), when compared to the placebo group. At 4 months, IgG1 was lower in the prebiotic group (95% CI: −1.55 [−3.55, −0.12]) compared to placebo group. Conclusion: This exploratory study shows that prebiotic consumption by lactating mothers selectively alters specific immunomodulatory proteins in HM. This finding is crucial for understanding how prebiotic dietary recommendations for pregnant and lactating women can modify the immune properties of HM and potentially influence infant health outcomes through immune support from breastfeeding.