Effects of maternal allergy and supplementation with ω‐3 fatty acid and probiotic on human milk oligosaccharides

Background Human milk oligosaccharides (HMOs) are complex carbohydrates that act as prebiotics, supporting infants' gut microbial colonization and immune development. HMO levels are influenced by several maternal factors, including genetics, diet, and health status. In this study, we aim to investigate the effects of ω‐3 PUFA (polyunsaturated fatty acids) and Limosilactobacillus ( L .) reuteri supplementation on HMO levels in colostrum and mature milk. Another aim is to compare HMO levels between allergic and non‐allergic mothers and to explore the correlation between HMOs and secretory immunoglobulin A (SIgA) in milk. Methods Milk samples ( n = 136) were collected from mothers enrolled in a clinical trial (PROOM‐3) designed to investigate the effect of pre‐ and postnatal supplementation with ω‐3 PUFA and L. reuteri on allergy development in early childhood. HMOs were measured in colostrum and mature milk collected 3 months postpartum using high‐performance anion exchange chromatography. SIgA was measured in colostrum, 1‐, 2‐, 3‐, and 4‐month milk using ELISA. Results The supplements did not affect HMO levels in colostrum or mature milk. However, maternal supplementation with ω‐3 PUFA decreased the HMO diversity over time. Additionally, allergic mothers expressed significantly lower levels of several HMOs compared to non‐allergic mothers. Additionally, SIgA correlated positively with fucosylated and negatively with sialylated HMOs. Conclusion Supplementation with ω‐3 PUFA could reduce the HMO diversity over the course of lactation. Also, maternal allergy seems to be associated with a reduction in levels of several HMOs. Furthermore, there is a possible dynamic interplay between HMOs and SIgA in milk. Trial Registration ClinicalTrials.gov ‐ID: NCT01542970