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Abstract
Background Singapore and Malaysia are neighbouring countries with similar ethnic make-up: Chinese, Indian, and Malays. However, Singapore is a high-income economy while Malaysia is a middle-income economy. Such a difference has resulted in some levels of dichotomy in diet and lifestyles. In this study, we sought to investigate the gut-ethnic variation across the two neighbouring countries with varying levels of economic development.
Methods A total of 439 relatively healthy Malaysian (n=190) and Singaporean (n=249) adults (>18) were included, comprising Chinese (n=240), Indian (n=74), Malay (n=40), and the indigenous Jakun community (n=85). The sequences were processed with DADA2 and annotated using the SILVA database.
Results Country of origin explained the most variation in the gut microbiota (PERMANOVA, Pseudo-F=80.798, R2=0.156, p=0.001; IDDF2021-ABS-0150 Figure 1. Ordination). Importantly, ethnicity was still significantly associated with the gut microbiota even after adjusting for the country, age and sex (PERMANOVA, Pseudo-F=4.206, R2=0.019, p=0.001). Several taxa were found to be differentially abundant across ethnicity (ANCOM-BC, q<0.05). Notably, Ligilactobacillus, a lactic acid bacteria, was elevated among Indians (IDDF2021-ABS-0150 Figure 2. Ancom.ci) and reduced among Malay (IDDF2021-ABS-0150 Figure 3. Ancom.cm) relative to Chinese, suggesting that differences in the dietary pattern were responsible for the observed gut variation. Jakun exhibited the most differentially abundant gut microbiota (IDDF2021-ABS-0150 Figure 4. Ancom), with an elevated abundance of 18, 6, 5, and 1 genera, families, order, and class, respectively. The higher diversity of the Jakun was likely a reflection of their more traditional way of life, which has been associated with better gut diversity and health, compared to the Chinese, Indian and Malay of both countries, in particular, the higher abundance of Methanobacteria in Jakun has been inversely associated with irritable bowel syndrome.
Conclusions Gut-ethnic differences persist across geographical regions, which was likely due to similar lifestyle and cultural practices by individuals sharing similar ancestry. These signals provide potential biomarkers on the role of the gut microbiota in the aetiology of the unequal disease burdens affecting the different ethnic groups in this multicultural region.