According to a recent study by Stanford University School of Medicine researchers, gut microbe deterioration from low-fibre diets may be inherited and irreversible over generations.
Microbiota-accessible carbohydrates (MACs) found in plant-derived fibre have a beneficial impact on gut microbiota. In the study, mice colonised with human gut microbes were fed a diet rich in dietary fibre (high-MAC) for 6 weeks and divided into two groups. One group was fed a low-MAC diet for 7 weeks, after which they returned to the high-MAC diet for a further 6 weeks. The control group was fed a high-MAC diet throughout the experiment. In both groups, diets were identical in terms of protein, fat and calorie content. After the first 7-week period, 60% of the bacterial species in the low-fibre group showed a dramatic decline in abundance compared with only 11% of the control group. When these mice were returned to a high-MAC diet, 33% showed a lower rate of abundance. The control group did not change significantly. Although gut bacteria in the mice that had consumed a low-fibre diet partly recovered, one-third of the original species did not see their gut microbiota fully restored despite their return to a high-fibre diet.
To study the influence of the different diets on subsequent generations, the researchers bred mice from the two groups and weaned their pups over four generations. By generation four of fibre deprivation, there was an irreversible disappearance of more than two-thirds of the bacterial species identified in the first-generation’s gut microbiota. This result was driven by the low-MAC diet and switching low-MAC-diet mice to the high-MAC diet did not influence the outcome. Although high dietary fibre was insufficient in restoring microbiota composition or diversity to control levels, faecal transplantation together with a high-MAC diet did result in microbiota diversity and composition restoration in the fourth-generation low-fibre mice.
These results support a model in which consuming a modern diet low in fibre could contribute to bacteria loss in the intestine over generations and may be responsible for the less diverse microbiota observed in the industrialised world compared with the diet among hunter-gatherers and rural agrarian populations.
In conclusion, according to the model used, adopting a high-fibre diet may be beneficial for the gut microbial ecosystem of both the person consuming the diet and their future generations. In short, these results suggest that gut microbiota diversity is a key regulator of host health.
Sonnenburg ED, Smits SA, Tikhonov M, Higginbottom SK, Wingreen NS, Sonnenburg JL. Diet-induced extinctions in the gut microbiota compound over generations. Nature. 2016;529(7585):212-215.