Background/Objectives: Despite increasing interest in the human gut microbiome, particularly in Bifidobacterium, studies focusing on traditionally living populations with high habitual dairy consumption remain limited. This study investigated species-level diversity, abundance, and regional variation of Bifidobacterium among healthy Mongolian adults and contextualized these findings within a global comparative framework. Methods: A total of 100 healthy adults were recruited from four Mongolian regions. Fecal samples were analyzed using species-resolved shotgun metagenomics, and dietary intake was assessed through a standardized food frequency questionnaire. Alpha- and beta-diversity metrics, differential abundance tests, and diet–microbe correlations were performed on members of the Bifidobacterium species. To assess the broader significance of the Mongolian Bifidobacterium profile, Shannon diversity was further compared against a curated global dataset comprising 1286 healthy adults from 29 countries using harmonized bioinformatic and statistical pipelines. Results: Shannon diversity within the Bifidobacterium genus was significantly higher in nomadic Mongolians, particularly those from Khuvsgul and Dundgobi, and strong geographic structuring was observed in beta-diversity analyses (PERMANOVA, p < 0.001). Nomadic populations showed higher relative abundances of B. adolescentis and B. angulatum, whereas B. pseudocatenulatum predominated in Ulaanbaatar. Although overall Bifidobacterium abundance was lowest in Bulgan, B. longum remained the dominant species in this region. Spearman correlation analysis with false discovery rate correction identified significant associations between dairy intake and specific Bifidobacterium species. Homemade yogurt and traditional dairy intake were positively associated with B. angulatum. B. catenulatum was positively associated with homemade yogurt, traditional dairy, and total fermented dairy intake, whereas factory milk intake was negatively associated with B. angulatum but positively associated with B. pseudocatenulatum. Mongolia ranked among the top eight of 30 countries for Bifidobacterium Shannon diversity though total Bifidobacterium abundance showed substantial inter-individual and regional variation. Conclusions: Mongolian adults exhibit relatively high Bifidobacterium diversity at both national and global scales. Traditional dairy consumption was associated with species-specific variation in Bifidobacterium composition, supporting the contribution of dietary practices to regional gut microbiota patterns.

Objective: This study aimed to characterize Bifidobacterium species in the gut microbiome of ethnic Mongolian individuals, determine their distribution based on geographic location, age, and sex, and isolate representative strains under laboratory conditions. Methods: A total of 100 stool samples were collected from 50 urban and 50 rural participants over the age of 18, with a balanced gender ratio. Rural participants were herders and maintained a traditional nomadic lifestyle. Data analysis was conducted using the R software and MetaPhlAn tool to profile microbial communities at the species level. Results: A total of 13 Bifidobacterium species were identified across the 100 samples. Species such as B. adolescentis, B. angulatum, B. longum, B. bifidum, B. catenulatum, B. dentium, and B. breve were predominantly found in rural participants, whereas B. pseudocatenulatum, B. ruminantium, B. animalis, B. scardovii, and B. kashiwanohense were more prevalent in urban participants. The overall species richness of Bifidobacterium was 2.9 times higher in rural participants than in urban ones. Culturable isolates frequently showed 2–3 morphologically distinct colony types per sample. Conclusions: Bifidobacterium species richness increased with age in rural participants, whereas it decreased with age in urban participants. Female participants had greater species diversity than males.

Mongolians traditionally consume a diet rich in animal-derived fats, often exceeding recommended limits for saturated fat intake. This pattern reflects both cultural preferences and the wide availability of dairy- and meat-based fats in rural and urban diets. This study investigates the consumption patterns and quality characteristics of commonly used vegetable oil and animal-derived fats in Mongolia, with a particular focus on sunflower oil, olive oil, rapeseed oil, clarified butter, and greaves. A total of 142 participants (57 males and 85 females, aged 18–84 years) were surveyed. Dietary fat intake was assessed using a structured food frequency questionnaire and food composition tables, including fats from traditional meals, fried foods, baked goods, snacks, and condiments. All participants reported regular consumption of both plant-based oils and animal-derived fats. Notably, animal-derived fats accounted for a significantly larger proportion of daily intake (Mean: 60.7 ± 50.9 g/day) compared to vegetable oils (Mean: 16.8 ± 17.6 g/day) (p < 0.0001, Wilcoxon test). Sunflower oil was the most widely consumed vegetable oil (63.8% of total plant oil intake), while homemade clotted cream (urum) and clarified butter ranked highest among animal-derived fats. Total dietary fat intake was significantly associated with gender (p = 0.003), occupational status (p = 0.030), and age group (p = 0.014), indicating demographic variations in dietary fat habits. Laboratory analyses were conducted on selected oils to determine their melting and freezing points, iodine number, total acid number, and content of unsaturated fatty acids. Results revealed that repeated heating led to increased acidity and a reduction in unsaturated fatty acids, indicating deterioration in oil quality. The findings suggest that Mongolian adults consume higher-than-recommended levels of saturated animal fats, with relatively low intake of unsaturated vegetable oils. This imbalance, combined with the use of repeatedly heated oils, may increase the risk of non-communicable diseases. Recommendations are provided to promote healthier oil choices and improve dietary fat quality in Mongolia.