Gut microbe damage from low-fibre diets may be inherited - and irreversible
The findings suggest damage over several generations to a gut microbe population may not be reversible with simple diet fixes as previously thought.
Microbiota-accessible carbohydrates (MACs) found in dietary fibre play a crucial role in shaping the body’s microbial ecosystem, and are notably reduced in the Western diet (high in fat and simple carbohydrates, low in fibre) compared with more traditional diets.
In the study, researchers from Stanford, Harvard and Princeton University fed ten mice a diet rich in plant-derived fibre from a high microbiota-accessible carbohydrate (MAC) diet for six weeks. These mice were then divided into two groups.
One group was fed a low-MAC diet for seven weeks, after which they were returned to the high-MAC diet for a further six weeks.
The control group were fed the high-MAC diet throughout the experiment.
Spot the difference
At the start of the experiment, the microbiota composition of both groups of mice was identical.
The diet-switching mice, while consuming the low-MAC diet, had an altered composition relative to the control group. Weeks after returning to the high-MAC diet, the microbiota of the diet-switching mice remained distinct from the control group.
To determine whether certain bacterial populations had been lost over the course of the diet switch, the researchers focused on operational taxonomic units (OTUs), which would indicate the prevalence and abundance of certain microbiota within each experimental group.
They identified 208 OTUs in the diet-switching group and 213 OTUs in the control group. When mice were switched from the high-MAC diet to the low-MAC diet, the researchers observed 60% of taxa (124 out of 208) decreased in abundance compared with only 11% of the control group (25 out of 213).
When these mice were returned to a high-MAC diet, 33% (71 out of 208) were less abundant. The control group did not change significantly (10% were less abundant; 22 out of 213).
“These data reveal two divergent qualities of the microbiota. First 59 of the 208 OTUs that exhibit diet-induced decline in abundance recovered with the reintroduction of MACs illustrating microbiota resilience over short time scales,” the study commented.
“Secondly, however, the low MAC-diet switch perturbation ‘scars’ on the microbiota.”
Change in diet
The researchers proposed a change in diet over hundreds of years that resulted in an adjustment in human gut microbiota, pointing to the agricultural revolution and the mass consumption of processed foods as turning points.
“The model used does not allow us to address microbiota changes that may have occurred as humans shifted from a hunter-gatherer lifestyle to one from a modern industrialised country.”
“Our data supports a model in which consuming a modern diet low in fibre contributes to the loss of taxa over generations, and may be responsible for the lower-diversity microbiota observed in the industrialised world. The data we present also hint that further deterioration of the Western microbiota is possible.”
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Source: Nature 529, 212–215
Published online ahead of print, DOI: 10.1038/nature16504
“Diet-induced extinctions in the gut microbiota compound over generations”
Authors: Erica D. Sonnenburg, Samuel A. Smits, Mikhail Tikhonov, Steven K. Higginbottom, Ned S. Wingreen & Justin L. Sonnenburg