Globalisation in the food industry has led to fewer people consuming traditional diets, a pattern believed to have had an adverse impact on human health due to its alteration of the gut microbial ecosystem.
A study led by Japan's Kyushu University compared the gut microbiota of 17 urban and 28 rural Thai school children between the ages of nine and 11, in relation to their dietary habits; the urban children resided in Bangkok, while the rural children lived in Buriram.
Input and output assessment
Dietary records were obtained via the children's parents and guardians, covering menu items, ingredients used, and quantity consumed at every meal, including breakfast, mid-morning snack, lunch, mid-afternoon snack, dinner, and post-dinner snack.
This information was collected over the course of seven days, and the researchers then calculated the daily energy and nutrient content of the foods consumed per child.
After this, they collected the participants' stool samples.
According to the dietary records, the children living in urban Bangkok typically consumed modern high-fat diets, while those living in rural Buriram tended to consume traditional low-fat, vegetable-based diets.
Based on the researchers' assessment of the stool samples, the urban children had significantly lower bacterial diversity than the rural children, as well as reduced faecal butyrate and proponiate levels, due to changes in their gut microbial communities.
The stool samples were also classified into five metabolotype (MT) groups, based on the children's metabolome profiles.
The first group, MT1 (17 samples), had high concentrations of short-chain fatty acids (SCFAs) and middle-chain fatty acids (MCFAs). The second, MT2 (seven samples), had a high level of amino acids.
The third, MT3 (six samples), had an abundance of arginine, while the fourth, MT4 (four samples), had a low level of metabolites.
The fifth group, MT5 (eight children), had a high level of amines.
It was also noted that MT1 and MT4 consisted mainly of stool samples from the rural children, while MT2 and MT3 consisted mainly of stool samples from the urban children, and MT5 contained three urban samples and five rural samples.
The researchers further wrote that MT1 and MT2 were "characteristic of children in Buriram and Bangkok, respectively".
Dietary differences
They reported that the average total fat intake amongst the urban children was over 35% of their total energy intake, the higher recommended level for children, according to the Food and Agriculture Organisation (FAO).
Furthermore, several earlier studies have shown that plant-based diets encourage colonic fermentation of SCFAs, and have a "profound effect on host health".
Rural microbiomes have also been said to possess higher capacity accept the intake of a range of sugars, suggesting that the human gut microbiome had initially evolved to utilise a wide variety of carbon sources, before this was compromised by excessive consumption of simple sugars.
Indeed, foods such as mung beans have been said to benefit the gut microbiome and as such, protect against the impact of a high-fat diet.
In addition, some personalised nutrition firms are making dietary recommendations to help improve customers' gut microbiome and in turn, reduce the risk of metabolic diseases like diabetes.
The researchers behind the current study concluded: "This study shows the benefit of high-vegetable Thai traditional diets on gut microbiota, and suggests that high-fat and low-vegetable urban dietary habits alter gut microbial communities in Thai children, which (has) resulted in the reduction of colonic SCFA fermentation.
"This study suggests that the transition of dietary habits from traditional to modern has distorted the functionality of gut microbiota of Thai children, notably SCFA productivity, through the alteration of their community structure.
"As a number of previous studies have demonstrate, plant-based diets promote colonic fermentation of SCFAs and have a profound effect on human health.
"The high-vegetable Thai traditional diets appears to benefit children in Thailand, and the lower level of faecal SCFAs appears to be a risk marker of dietary urbanisation in Thailand."
Source: Frontiers in Microbiology
https://doi.org/10.3389/fmicb.2018.01345
"Urban Diets Linked to Gut Microbiome and Metabolome Alterations in Children: A Comparative Cross-Sectional Study in Thailand"
Authors: Juma Kisuse, et al.