News

Diets shape your gut microbes

Biplab Das

doi:10.1038/nindia.2019.49 Published online 23 April 2019

A research team has identified unique and diverse populations of microbes in the gut of two unrelated groups of healthy Indians living off different diets1 — one animal-based and the other a a plant-based diet.

The researchers say that the difference in food habits may have shaped the diversity of the microbes that inhabit the guts of these populations. Gut microbes are known to regulate key metabolic processes and immune responses in the human body. They have also been shown to have a role in modifying behaviours.

Beyond the obvious link between diet and gut microbes, this study throws ups data that could help understand the possible association between some microbes and metabolic diseases, such as obesity and diabetes, says Vineet Sharma, one of the researchers from the Indian Institute of Science Education and Research in Bhopal, India.

India is home to myriad ethnic groups, with diverse lifestyles and food habits. But little is known about how such factors modulate the types of gut microbes that Indians harbour.

To gain new insights into this aspect, the researchers, collaborating with US-based scientists, sequenced the genes of gut microbes isolated from two different adult populations from Kerala and Madhya Pradesh. The individuals from Kerala lived on a diet rich in rice, meat and fish, whereas the people from Madhya Pradesh ate plant-derived products such as wheat and fat-rich foods such as dairy products.

Prevotella species emerged as the most abundant and key bacteria. Mitsuokella, Lactobacillus and Megasphaera species were also highly abundant in Indians compared with people living elsewhere in the world.

The Prevotella were found in the gut of people who consumed plant-based diets. Lactobacillus, Megasphaera and Mitsuokella were dominant in people whose diet contained fermented foods and dairy products. Bacteroides and Clostridium, on the other hand, were abundant in people who ate animal-based products.

The diet and bacteria were found to regulate the levels of specific fatty acids in the gut. Lauric acid, a medium-chain fatty acid known to prevent fat deposition and act as an anti-inflammatory agent, was highly abundant in people from Kerala whose diet contained coconut oil. The people who ate carbohydrate-rich foods had in their serum higher levels of branched-chain fatty acids that are known to increase the risks for diabetes.

This study, conducted among healthy individuals, shows that most of the gut microbes are friendly, but they have sinister roles too, with recent research showing that they could be linked to specific diseases. In a previous study, Sharma and his colleagues had shown that the amount of Lactobacillus species was almost 80 times more in the gut of autistic children than the healthy children2. They have also found a strong link between the pulmonary tuberculosis and the activity of specific gut microbes3.

Such an emerging picture linking gut microbes to diseases makes them potential candidates for disease biomarkers, says Sharma.

The research adds a new dimension to ongoing research on gut microbes linking such microbes with metabolites and dietary habits, says Mojibur Khan who studies gut microbes at the Institute of Advanced Study in Science and Technology in Guwahati, Assam, and is not involved with the research.  “The microbial population is not solely influenced by dietary factors. Ethnicity and geography also shape them,” Khan adds.


References

1. Dhakan, D. B. et alThe unique composition of Indian gut microbiome, gene catalogue and associated faecal metabolome deciphered using multi-omics approaches. GigaScience. 8, (2019) doi: 10.1093/gigascience/giz004

2. Pulikkan, J. et alGut microbial dysbiosis in Indian children with autism spectrum disorders. Microb. Ecol. 76, 1102-1114 (2018)

3. Maji, A. et alGut microbiome contributes to impairment of immunity in pulmonary tuberculosis patients by alteration of butyrate and propionate producers. Environ. Microbiol. 20, 402-419 (2018)