Scientists from the Stanford University School of Medicine found that a low-fiber diet causes an irreversible depletion of gut bacteria diversity, and this condition can be passed on to future generations.
According to the researchers, low-fiber diets cause some gut bacterial species to go extinct. Once this happens, switching to a high-fiber diet will not restore the lost bacteria back into the gut. The condition becomes worse in the succeeding generations, the researchers said.
"Numerous factors including widespread antibiotic use, more-frequent cesarean sections and less-frequent breastfeeding have been proposed for why we see this depletion in industrialized populations," lead researcher Erica Sonnenburg said in a press release. "We asked ourselves whether the huge difference in dietary fiber intake between traditional and modern populations could, alone, account for it."
The research team studied mice that were carefully bred under sterile conditions and then ntroduced to human gut bacteria. One group was fed a low-fiber diet and another group was fed a high-fiber diet.
In two weeks, fecal samples from the low-fiber mice showed that more than half of their original gut bacteria were reduced by about 75 percent while some species completely disappeared.
The low-fiber mice were switched to a high-fiber diet for four weeks, but their gut bacteria merely recovered partially; a third of the initial gut bacteria were lost. The high-fiber mice did not show any changes at any stage of the experiment.
To see the effects across generations, the researchers bred the mice and fed the two groups as before: low-fiber diet and high-fiber diet. The offspring of the low-fiber mice showed a reduced diversity in gut bacteria.
Interestingly, the fourth generation low-fiber mice only had about a quarter of the gut bacteria of the first generation mice. Switching them to a high-fiber diet did not increase the diversity in their gut bacterial ecosystem, indicating that some gut bacterial species had been irreversibly lost.
"Our data illustrate that taxa driven to low abundance when dietary MACs are scarce are inefficiently transferred to the next generation, and are at increased risk of becoming extinct within an isolated population," the researchers wrote.
The study was published online Jan. 13 in the journal Nature.
