Not trying to be gross or anything, but pooping is really important. And you know what makes you poop? Fiber!
Sure, you knew that high-fiber diets were beneficial to the gut, but some studies are beginning to show that low-fiber diets could be detrimental to a gut’s microbiome.
Justin Sonnenburg, of Standford University, wanted to figure out just how bad low-fiber diets are for the gut so he created an experiment to figure out why fiber is so darn important.
Sonnenburg started with a simple idea: that possibly, just possibly, fiber is just as important to the trillions of microbes in our guts as it is to us. “Fiber is a broad term that includes many kinds of plant carbohydrates that we cannot digest. Our microbes can, though, and they break fiber into chemicals that nourish our cells and reduce inflammation,,” The Atlantic reports. “But no single microbe can tackle every kind of fiber. They specialize… This means that a fiber-rich diet can nourish a wide variety of gut microbes and, conversely, that a low-fiber diet can only sustain a narrower community.”
To get a better look and just how important fiber is to microbes, Sonnenburg, a graduate student, and his wife, embarked on an experiment. “The researchers started with mice that had been raised in sterile bubbles and then loaded with identical collections of gut microbes. They then fed these mice a high-fiber diet, before randomly switching half of them to low-fiber chow for seven weeks,” The Atlantic reports. “Predictably, the fall in fiber caused upheavals in the rodents’ guts. In the low-fiber group, the numbers of 60 percent of the local microbe species fell dramatically, and some remained low even after the mice returned to high-fiber meals. Those seven low-fiber weeks left lingering scars on the animals’ microbiomes.”
Apparently, these scars stick around and can affect generations. Why? Well, that’s kind of gross, but interesting. Mice eat each others’ poop and baby mice often acquire their parents microbes by eating their poop. During the experiment, the researchers saw that the mice who had parents that were in the low-fiber group had “narrower microbiomes.”
The researchers also found that these changes were hard to reverse. “The fourth-generation mice switched to high-fiber meals, some of the missing microbes rebounded, but most did not,” The Atlantic reports. “In other words, these species weren't just lying in wait in small numbers, waiting for the chance to bloom again; they had genuinely vanished. The only way of restoring these missing microbes was through a fecal transplant—loading them with the entire gut microbiomes of rodents that had always eaten a high-fiber diet.”
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While this experiment only involved mice, The Atlantic reports that “these changes parallel those that have taken place over the course of human history."
Other research has shown that "the gut microbiomes of Western city-dwellers are less diverse than those of rural villagers and hunter-gatherers." Hunter-gatherers tend to eat more plant foods, so, they get more fiber. "Sonnenburg's concern is that these changes play out over millennia, and hosts and microbes have time to acclimate to their new relationships. By contrast, our modern diets and lifestyles are changing our microbiomes very quickly, leaving us with communities that we haven't adjusted to.”
I don’t know about you, but I think I’m going to go eat a bunch of vegetables right now… BRB.
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