Human milk oligosaccharides (HMOs) exert beneficial effects on the gut microbiota, enhance resistance to infections, support immune development, and contribute to brain/cognitive development. Milk-derived extracellular vesicles (MEVs) contain a high abundance of immunity- and development-related microRNAs (miRNAs). These components are abundant in breast milk. In the case of HMOs, the composition varies due to factors such as lactation stages, geographic location, ethnicity, genetics, and the environment. The composition of HMOs is significantly influenced by the genetic status of two key genes: FUT2 (Secretor gene) and FUT3 (Lewis gene). In this study, we broadly categorized them as secretors or non-secretors.
We investigated the changes in the concentrations of HMOs and MEVs during 4 months of lactation in Japanese women and explored the relationship between HMOs and miRNAs present in MEVs.
The concentrations of most HMOs significantly decreased over time. The number of MEVs did not change significantly over the study period. Interestingly, 3'-sialyllactose and lacto-N-fucopentaose III were inversely correlated with many of the top 20 most abundant miRNAs. Moreover, miRNAs in MEVs, which are associated with immunity and development, were more abundant in secretors than in non-secretors during early lactation. Several HMOs were detected in MEVs.
This study enabled a detailed characterization of changes in HMOs and MEVs in the breast milk of Japanese women throughout the course of the first 4 months of lactation. A potential association between the concentrations of HMOs and miRNAs was also observed, suggesting that these components might influence each other. These findings are significant for promoting healthy infant development and growth, as well as for improving infant formula composition.
Copyright © 2025 Morozumi, Izumi, Tsuda, Tabata, Nakamura and Miyaji.

Background/Objectives: HMOs are the third most abundant solid component after lactose and fats in human milk. This study aimed to examine the relationships between maternal diet and HMO composition and concentration in human milk among lactating women in Latvia. Methods: Pooled 24 h human milk samples, 72 h food diaries, and questionnaires on anthropometric and sociodemographic characteristics were collected from 68 exclusively breastfeeding women residing in Latvia. HMOs were analyzed by UHPLC/FLD, and dietary data were analyzed using the Estonian NutriData program. Results: The eight most abundant HMO structures were determined with total concentration ranging between 178.66 and 32,910.09 mg L-1. 2'-FL was the most prevalent HMO in human milk (median concentration-3647 mg L-1), followed by 3'-FL (1436.74 mg L-1). Participants had an insufficient intake of vegetables, fruits, berries, milk and dairy products, and fish, leading to vitamin A, vitamin C, folate, and iodine intakes lower than recommended for lactating women. Limitation or exclusion of milk and dairy products from the diet was associated with a higher 2'-FL concentration in human milk (p = 0.037). Preference for "zero sugar" products was associated with a higher 3'-FL, 6'-GL, LNnT, 6'-SL, LNDFH II concentration in human milk (p < 0.050). Dietary supplement use (e.g., vitamin D, calcium) was also associated with differences in HMO composition and concentration in milk (p < 0.050). Conclusions: The findings highlight the importance of dietary habits and supplement use in shaping HMO profiles, though more human milk samples and dietary data need to be evaluated to draw further conclusions.

Breast milk composition is influenced by maternal diet. This study aimed to evaluate if supplementation of maternal diet with a prebiotic fibre, through its potential effect on milk composition, can be a leverage to orientate the gut microbiota of infants in a way that would be beneficial for their health. Twelve sows received a diet supplemented with short chain fructo-oligosaccharides or maltodextrins during the last month of gestation and the lactation. Oligosaccharidic and lipidomic profiles of colostrum and mature milk (21 days), as well as faecal microbiota composition and metabolomic profile of 21 day-old piglets were evaluated. The total porcine milk oligosaccharide concentration tended to be lower in scFOS-supplemented sows, mainly due to the significant reduction of the neutral core oligosaccharides (in particular that of a tetrahexose). Maternal scFOS supplementation affected the concentration of 31 lipids (mainly long-chain triglycerides) in mature milk. Faecal short-chain fatty acid content and that of 16 bacterial metabolites were modified by scFOS supplementation. Interestingly, the integrative data analysis gave a novel insight into the relationships between (i) maternal milk lipids and PMOs and (ii) offspring faecal bacteria and metabolites. In conclusion, scFOS-enriched maternal diet affected the composition of mature milk, and this was associated with a change in the colonisation of the offspring intestinal microbiota.
© 2024. The Author(s).

Kefir is a fermented dairy beverage that has been consumed by humans for centuries, but poorly studied in pets. The objective of this study was to determine the effects of commercial or traditional kefir supplementation on apparent total tract macronutrient digestibility (ATTD) and fecal characteristics, microbiota populations, and metabolite and immunoglobulin (Ig) A concentrations of healthy adult dogs. Twelve healthy adult dogs (5.67 ± 1.72 yr, 7.27 ± 1.15 kg) were used in a replicated 3 × 3 Latin square design (n = 12/group). All dogs were fed a commercial diet and allotted to 1 of 3 treatments (60 mL/d): 2% reduced-fat milk treated with lactase [CNTL; 4.57E + 03 lactic acid bacteria (LAB) colony-forming units (CFU)/mL], commercial kefir (C-Kefir; 6.95E + 04 LAB CFU/mL), or traditional kefir brewed daily from 2% reduced-fat milk and kefir grains (T-Kefir; 1.79E + 09 LAB CFU/mL). The experiment was composed of three 28-d periods, with each consisting of a 22-d transition phase, a 5-d fecal collection phase, and 1 d for blood collection. Fecal samples were collected for determination of ATTD and fecal pH, dry matter, microbiota, and metabolite, and IgA concentrations. Data were analyzed using the Mixed Models procedure of SAS 9.4. The main effects of treatment were tested, with significance set at P ≤ 0.05 and trends set at P ≤ 0.10. Kefir products differed in microbial density and profile, but fecal microbiota populations were weakly impacted. Bacterial alpha diversity tended to be greater (P = 0.10) in dogs fed T-Kefir than those fed CNTL. Bacterial beta diversity analysis identified a difference (P < 0.0004) between dogs-fed CNTL and those fed C-Kefir. Dogs-fed C-Kefir tended to have a greater (P = 0.06) relative abundance of Fusobacteriota than those fed CNTL or T-Kefir. Dogs-fed T-Kefir had a greater (P < 0.0001) relative abundance of Lactococcus than those fed CNTL or C-Kefir. Dogs-fed T-Kefir also tended to have a lower (P = 0.09) relative abundance of Escherichia Shigella and greater (P = 0.09) relative abundance of Candidatus stoquefichus than dogs-fed CNTL or C-Kefir. Dogs-fed C-Kefir tended to have lower (P = 0.08) fecal valerate concentrations than those fed CNTL or T-Kefir. All other measures were unaffected by kefir treatments. Our results suggest that kefir supplementation had minor effects on the fecal microbiota populations and fecal metabolite concentrations of healthy adult dogs without impacting ATTD, fecal characteristics, or fecal IgA concentrations.
© The Author(s) 2023. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Human Milk Oligosaccharides (HMOs) are abundant carbohydrates fundamental to infant health and development. Although these oligosaccharides were discovered more than half a century ago, their biosynthesis in the mammary gland remains largely uncharacterized. Here, we use a systems biology framework that integrates glycan and RNA expression data to construct an HMO biosynthetic network and predict glycosyltransferases involved. To accomplish this, we construct models describing the most likely pathways for the synthesis of the oligosaccharides accounting for >95% of the HMO content in human milk. Through our models, we propose candidate genes for elongation, branching, fucosylation, and sialylation of HMOs. Our model aggregation approach recovers 2 of 2 previously known gene-enzyme relations and 2 of 3 empirically confirmed gene-enzyme relations. The top genes we propose for the remaining 5 linkage reactions are consistent with previously published literature. These results provide the molecular basis of HMO biosynthesis necessary to guide progress in HMO research and application with the goal of understanding and improving infant health and development.
© 2022. The Author(s).