Asia differs substantially among and within its regions populated by diverse ethnic groups, which maintain their own respective cultures and dietary habits. To address the diversity in their gut microbiota, we characterized the bacterial community in fecal samples obtained from 303 school-age children living in urban or rural regions in five countries spanning temperate and tropical areas of Asia. The microbiota profiled for the 303 subjects were classified into two enterotype-like clusters, each driven by Prevotella (P-type) or Bifidobacterium/Bacteroides (BB-type), respectively. Majority in China, Japan and Taiwan harbored BB-type, whereas those from Indonesia and Khon Kaen in Thailand mainly harbored P-type. The P-type microbiota was characterized by a more conserved bacterial community sharing a greater number of type-specific phylotypes. Predictive metagenomics suggests higher and lower activity of carbohydrate digestion and bile acid biosynthesis, respectively, in P-type subjects, reflecting their high intake of diets rich in resistant starch. Random-forest analysis classified their fecal species community as mirroring location of resident country, suggesting eco-geographical factors shaping gut microbiota. In particular, children living in Japan harbored a less diversified microbiota with high abundance of Bifidobacterium and less number of potentially pathogenic bacteria, which may reflect their living environment and unique diet.

Loss of traditional diets by food globalization may have adverse impact on the health of human being through the alteration of gut microbial ecosystem. To address this notion, we compared the gut microbiota of urban (n = 17) and rural (n = 28) school-aged children in Thailand in association with their dietary habits. Dietary records indicated that children living in urban Bangkok tended to consume modern high-fat diets, whereas children in rural Buriram tended to consume traditional vegetable-based diets. Sequencing of 16S rRNA genes amplified from stool samples showed that children in Bangkok have less Clostridiales and more Bacteroidales and Selenomonadales compared to children in Buriram and bacterial diversity is significantly less in Bangkok children than in Buriram children. In addition, fecal butyrate and propionate levels decreased in Bangkok children in association with changes in their gut microbial communities. Stool samples of these Thai children were classified into five metabolotypes (MTs) based on their metabolome profiles, each characterized by high concentrations of short and middle chain fatty acids (MT1, n = 17), amino acids (MT2, n = 7), arginine (MT3, n = 6), amino acids, and amines (MT5, n = 8), or an overall low level of metabolites (MT4, n = 4). MT1 and MT4 mainly consisted of samples from Buriram, and MT2 and MT3 mainly consisted of samples from Bangkok, whereas MT5 contained three samples from Bangkok and five from Buriram samples. According to the profiles of microbiota and diets, MT1 and MT2 are characteristic of children in Buriram and Bangkok, respectively. Predicted metagenomics indicated the underrepresentation in MT2 of eight genes involved in pathways of butyrate biosynthesis, notably including paths from glutamate as well as pyruvate. Taken together, this study shows the benefit of high-vegetable Thai traditional diets on gut microbiota and suggests that high-fat and less-vegetable urban dietary habits alter gut microbial communities in Thai children, which resulted in the reduction of colonic short chain fatty acid fermentation.

Pyrosequencing analysis of intestinal microflora from healthy Thai vegetarians and non-vegetarians exhibited 893 OTUs covering 189 species. The strong species indicators of vegetarians and non-vegetarians were and as well as bacteria close to with % relative abundance of 16.9 and 4.5-4.7, respectively. Core gut microbiota of the vegetarian and non-vegetarian groups consisted of 11 and 20 different bacterial species, respectively, belonging to Actinobacteria, Firmicutes, and Proteobacteria commonly found in both groups. Two species, and , had a prevalence of 100% in both groups. Three species,, , and, showed up in most vegetarians, whereas more diversity of ,, various species of ,, , and different species of and were found in most non-vegetarians. Considering the correlation of personal characters, consumption behavior, and microbial groups, the age of non-vegetarians showed a strong positive correlation coefficient of 0.54 ( = 0.001) to but exhibited a moderate one to and . Only a positive moderate correlation of body mass index and appeared. Based on the significant abundance of potential pathogens, the microbiota of the non-vegetarian group showed an abundance of potential pathogen varieties of ,, and , whereas that of the vegetarian group served for only. These results implied that the microbiota of vegetarians with high abundance of and low potential pathogen variety would be a way to maintain good health in Thais.

In Thailand, food consumption by people from each region is different. This can be an important environmental factor which shapes the gut microbiota further affecting their health. This study aimed to use quantitative PCR (qPCR) to investigate the intestinal microbial community in 60 healthy children (aged 8-11 years) living in specific areas, namely central (CT) and northeastern (NE) Thailand where each region has its own typical food consumption. The children from NE had significantly higher consumption frequency of meat (chicken and beef), a wide variety of carbohydrate sources (noodle, fermented rice and sweet potato) including vegetables and fruit, while in CT, there was a significant preference for rice, breakfast cereal and cow milk. The qPCR analysis resulted in significantly higher abundance of lactobacilli, Clostridium coccoides-Eubacterium rectale, Clostridium leptum, Prevotella and Bacteroides fragilis in children from the NE region. However, no significant difference in the count of Bifidobacterium spp., Enterobacteriaceae and methanogens was observed. Considering the correlation of food sources and microbial groups, the consumption frequency of vegetables showed a moderately positive correlation coefficient of 0.42 and 0.34 to the Lactobacillus group (P = 0.001) and the Prevotella group (P = 0.008), respectively, while a diet of fish and beef showed a moderately negative correlation coefficient of -0.41 (P = 0.001) and -0.33 (P = 0.09) to Bifidobacterium spp., respectively. Our results suggested that high frequency consumption of varieties of carbohydrates, protein sources, fruits and vegetables by the NE children promoted a high abundance of bacterial species in the phyla Firmicutes and Bacteroidetes.

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