What You Eat: the Main Factor in Determining Your Microbiota

A new study out of Washington University in St. Louis shows, yet again, that even species matters less than what you eat and your lifestyle in determining the composition of your gut bacteria.[i]

These researchers analyzed the fecal microbiota a of 18 wild chimpanzees and 28 wild gorillas. They also collected fecal samples from 81 humans that live just outside the national parks (in the Republic of the Congo) where the animals lived.  These were all compared to samples from 18 chimps and 15 gorillas living in zoos within the USA.   Then all these samples were compared to other published data on hunter-gatherers, rural agriculturalists, urban humans from a wide variety of countries, including the United States.

Their results:  “These results indicate that captive ape microbiomes from the USA were more similar to that of the Congolese humans than to the wild apes …the gut bacteria of apes in zoos in the United States are more similar to people who eat a ‘non-western’ diet than they are to their wild ape cousins.”  That is, the animals’ in zoos, eating a heavily plant-based diet (but not a wild diet), have gut microbiomes that resemble humans, whether in the USA or the Republic of the Congo, who also eat a similar plant-based diet.  Geography did not matter and species (i.e. human or animal) did not matter:  diet does.

They point out that wild chimps and gorillas eat natural plants, very high in fiber, very low in animal protein, while captive animals “…consume human agricultural products.”  Another major difference between the captive and the wild animals:  the latter have never been exposed to antibiotics.

What strikes me as extremely interesting is that captive animals have a higher abundance of Prevotella (including P. copri), which as you know from reading my posts these past few weeks (for example, here), is associated with a high fiber (i.e. non-western) diet.  In fact, the Congolese humans tested, who eat a non-western diet, showed the same high levels of Prevotella. The researchers postulate that this difference, between captive and wild animals, is due to the actual composition of the fibers they each eat.

Another type of bacteria, one I am not familiar with,  Treponema, was also found in captive animals and non-Western-diet humans.  This commensal bacteria is mostly absent from humans living in industrialized countries, but “…have been found in abundance in human populations with non-Westernized lifestyles, including Hadza hunter-gatherers…”  Because of this, it is thought to be an “ancestral” species, suggesting that perhaps some of these kinds of bacterial, lost to us in the industrialized world, can still be (thankfully) found in other kinds of animals and the rare human.  (We don’t yet know, of course, how important some of these “ancestral” species may turn out to be, but I for one find it comforting to know there are still repositories for them, should future research prove them to be useful for our health.)

The researchers conclude that, “Our findings indicate that the microbiome of closely related host species may be molded by changes in diet and the degree of antibiotic exposure despite their geographic location.”  Reading this, I immediately thought about a post I wrote in November of 2018, The Negative (Biome) Side of Moving the USA: “Researchers looked at people from Southeast Asia and found that there was a significant reduction in the diversity of gut microbes with each subsequent generation, culminating with their microbiota resembling those of Americans of European origin.”  When these immigrants came to the USA, their microbiomes showed high levels of Prevotella but as they, and then each subsequent generation, began to eat a typical western diet, this very rapidly shifted:  ““Even a short period of residence in the United States was sufficient to induce pronounced increases, in some cases over 10-fold, in the ratio of Bacteroides to Prevotella.”

I think this must be about the 100th time I’ve concluded a post with a reminder to eat your vegetables!    🙂


[i] Campbell TP, Sun X, Patel VH, Sanz C, Morgan D, Dantas G. The microbiome and resistome of chimpanzees, gorillas, and humans across host lifestyle and geography. The ISME Journal. March 20, 2020. DOI: 10.1038/s41396-020-0634-2

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