Eat your vegetables, feed your microbiome

Your mother was right: vegetables are good for you. Not only do they contain essential nutrients but they also feed your microbiome with fiber.

For each of our body cells, we carry around ten microbe cells. In this light, the definition of “we” could be refined. It would be more appropriate to state that we, the microbiome, tolerate the conceit of body cells to suit our own needs. The body cells of so-called civilized societies haven’t been serving us well. Our population has declined in comparison to those in the majority world who eat more fiber and take fewer antibiotics.

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It’s counterintuitive that modern societies, while relatively free of infectious diseases that cause inflammation, suffer from inflammatory diseases. Antibiotics have reduced deadly diseases while inflammatory, autoimmune, and allergic diseases are on the rise. If infection is not causing these diseases, what is?

It seems that we (microbiome et al) have traded one disease for another. In reducing infectious disease with antibiotics, we have killed off the bacteria that suppress autoimmune diseases such as asthma.

Brett Finlay, a microbiologist at the University of British Columbia, explored this connection. He found that mice treated with the antibiotic vancomycin had an increased risk of asthma later. The antibiotic had killed beneficial bacteria that are part of the clostridial group.

The clostridial group is related the scourge of hospitals: Clostridium difficile which causes death by diarrhea. But where C. difficile prompts endless inflammation and bleeding, bacteria in clostridial clusters do just the opposite—they keep the gut healthy and soothe the immune system. Moises Velasquez-Manoff explains in Scientific American:

“Scientists are now exploring whether these microbes can be used to treat a bevy of the autoimmune, allergic and inflammatory disorders that have increased in recent decades, including Crohn’s and maybe even obesity.”

The exact cause of inflammatory bowel disease remains a mystery but the picture is becoming clearer. Finlay’s findings confirm earlier results from Harry Sokol, a gastroenterologist in Paris. He ran laboratory tests on his patients with Crohn’s disease, a chronic inflammatory disorder of the gut.

All his patients had one thing in common –a scarcity of just one common bacterium, Faecalibacterium prausnitzii. Rather than “bad” microbes causing disease, maybe a could a single “good” microbe could prevent disease. Studies suggest that antibiotics may deplete the very bacteria that favorably calibrate the immune system, leaving it prone to overreaction.

Our microbiome is more integrated into ourselves than previously thought. The state of our gut influences our state of our mind. Happy bacteria love munching on plant fiber, something we get too little of. Some of the byproducts of this munching include neurotransmitters and metabolites that act on the brain.

Our brains respond through the brain-gut connection, the vagus nerve, to help calibrate our immune system. Studies on mice with sterile guts by John Cryan, a neuroscientist in Ireland, indicate how profound the effects of our microbiome is. He found that sterile mice lacked the ability to even recognize other mice with whom they interact.

We kill off gut bacteria with antibiotics, and fail to feed them with fiber at our peril; leaving us susceptible to  anxiety, depression and even autism.

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