What happens when your gut-bacteria colonies get gentrified?
Nature Boy looked doubtfully at the meal.
“I think my junk-food-eating gut bacteria are going to riot if I keep eating all these salads, steamed vegetables and grains. It’s been more than almost six months since they’ve had a good feed.”
“You’ll be fine,” I said, passing him a bowl of chopped kale, walnuts and apple.
“I don’t know,” he said. “People revolt with their bellies, and my gut colonies of Pizzabacilli and Doritosphilia are a big part of my belly.”
We both paused and looked down at his belly.
“Looks like there’re less there than there used to be,” I say.
“That’s the problem. All these greens-, bean- and fibre-friendly microbes that you’re cultivating with this food are gentrifying my intestinal real estate. The original occupants aren’t happy about it and they’re getting restless — Don’t look at me like that, I’m just warning you. It could get messy if I don’t throw them a crust soon … preferably one stuffed with high-fat, rubbery cheese and laden with pepperoni.”
We — that is, I— have been on a wholefoods kick lately. Tired of feeling tired and sick of zombie-like mid-afternoon slumps (Must. Sleep. Now.), I’ve overhauled my— ahem, our — eating habits.
Most of the food in the house these days doesn’t come sealed in foil or plastic sacks or boxes. And, to date, no one has managed to grow carrots or heads of lettuce with built-in nutrition facts tables to show how many grams of carbohydrates, fats, salt, calcium, vitamins, etc., a serving contains.
But, as Nature Boy pointed out, it’s not just what you eat, it’s what you feed.
Thanks to the wonders of gene sequencing, we now know that as many as 100 trillion individual microbes live in the human gut. These include fungi, viruses, microbes known as archaea — which scientists once thought were bacteria but are actually something different — as well as some 15,000 species of bacteria.
Researchers estimate that all of the microbes in one typical adult human intestine weigh about as much as the same adult’s brain — about 1.25 kilograms.
Most of these microbes hang out in our lower intestines, where they do vital work to keep us, their hosts, healthy and happy.
They break down plant fibre in the food we eat and help us absorb vitamins, minerals and other nutrients from our food. Some manufacture crucial-to-us vitamins as waste products.
They neutralize harmful chemical by-products of the digestive process. They regulate gut-oxygen and gut-acidity levels. They police each other. They control inflammation and other immune responses. They protect against disease. They may even help regulate hormones such as insulin and stress hormones.
Those are the good guys. Others — including those that thrive on high quantities of super-processed sugar and pizza — are less desirable, but we can tolerate them in low numbers — kept low by the entire gut community.
Gut bugs feed on what we feed them. However, they’re particular about who dines on what. Each species brings its own special skills and dietary needs to the intestinal buffet.
Some specialize in breaking down fibre found in citrus fruits. Some are skilled at snacking on the cellulose that makes celery, lettuce and peppers crunchy. Some prefer the pectin found in apples, plums and pears. Bean-eating bacteria bust apart the long carbohydrates in kidney beans and black-eyed peas, releasing gases that then need to be vented.
Some stick to snacking on sugar. If there’s a food, there’s a gut microbe with the tools to deal with it.
Feed it what it needs, and a microbial species thrives. Starve it and it fails, and neighbouring species that can feed on what’s available take over.
Researchers who spend way too much time with poo have found that species-population levels within a person’s gut community can change within hours after he or she has eaten.
So, when Nature Boy complains that his pizza-phillic and Doritos-specialist gut critters are complaining about not getting enough of their particular food groups, he has a point.
Not that it’s a good point.
But it is a point.
“Well, then, if they can’t get bread and rubbery cheese and orange food dye,” I told him, pointing to a plate of tofu, “let them eat bean cake.”
“Now you’re just asking for trouble — explosive trouble,” he said.