Imagine for a moment that what you eat might have an impact on the intestinal health of your children. And their children. And so on and so forth. That is exactly what scientists at the Stanford University School of Medicine believe happens from one generation to the next. And eating plenty of fiber, they say, may be the key to preserving intestinal diversity.
In a study funded by the National Institutes of Health, researchers used two different groups of mice to determine the effects of a low-fiber diet on several generations of a species. Both groups of mice had been raised in a bacteria-free environment—meaning they had no microbial inhabitants of any kind in their bodies. Scientists then transferred human gut bacteria into the guts of the mice, and each group was fed either a high-fiber diet or an extremely low-fiber diet. What happened next was eye-opening.
The mice with barely any fiber in their diets experienced a drastic decrease in the number and type of microbes present in their guts. And four generations later, the lack of fiber caused “irreversible losses” in terms of gut microbiota: numbers of more than half of the bacterial species plummeted by over 75 percent, and some were wiped out completely. Perhaps even more alarming, just adding more fiber to the diet was not enough to undo the effects.
According to study authors, when an entire population suffers such a broad-scale loss of important gut microbes, it may never recover. And not surprisingly, people living in industrial societies like ours are already at risk because our diets consist mainly of pre-packaged, heavily processed foods that contain very little fiber. In fact, previous studies have shown that compared to our hunter-gatherer ancestors, today’s modern humans are greatly lacking in gut diversity.
Was there a bright side? Yes. It seems fecal transplantation—a relatively new practice in which healthy, bacteria-rich stool is transplanted from a donor to a recipient in need—was effective at bringing back the lost species of bacteria. In fact, in just over a week after the procedure, the microbial populations of both groups of mice were identical.