The transition from a non-westernized to westernized gut microbiome in Indian-Immigrants and Indo-Canadians is associated with dietary acculturation

Abstract

Background: Indian immigration to westernized countries has surged in recent years, with this demographic facing a higher risk of Inflammatory Bowel Disease (IBD) after migration. Studying the gut microbiome is crucial to understanding the factors contributing to IBD, yet Indians remain underrepresented in microbiome research, Objective: This study investigates the gut microbiome of Indians residing in India, Indian immigrants in Canada, and Canadians of Indian ancestry to understand the impact of westernization on their gut. Given the higher risk of IBD among Indo-Canadians, these results provide insight into how westernization of the gut microbiome may influence incidence of IBD. Stool samples were collected from healthy Indians in India, Indian Immigrants in Canada, Indo-Canadians, plus Canadian-borne individuals with European descent and Euro-Immigrants as non-Indian/westernized controls (N = 174). 16S rRNA gene and shotgun sequencing compared microbial taxa and functional profiles across groups. Dietary and demographic data were collected to assess lifestyle patterns. Results: Indians and Indo-Immigrants had distinct gut microbiotas from westernized groups, with high abundances of Prevotella spp. and a CAZyme profile reflecting their traditional high complex carbohydrate diet. The Indian microbiome also showed characteristics of high bacterial cell turnover, pathogenic potential, and stress tolerance, indicating their gut may be better primed to handle stressors on the gut. Indo-Canadians displayed a transitional microbiome towards westernization, which followed a pattern of increasing dietary acculturation. Conclusions: The shift from a non-westernized to westernized microbiome in Indo-Canadians highlights the significant influence that westernization and dietary acculturation has on the gut microbiome. Given that 44% of the Canadian population is made up of first- and second-generation immigrants and westernized practices are being adopted worldwide, future research should investigate the health implications that such microbiome transitions have on immigrant populations and newly industrialized nations.