ASK DR.BETH | By Dr. Beth Prinz
Going With Our Guts: Mutual Microbes & Us
Q. I’ve been reading a lot about probiotics and beneficial bacteria. What’s going on down there in my gut?
A. You are what you eat. Who hasn’t heard this before? Please take a moment to consider the importance of this statement, given the fact that only 10 percent of our cells, and one percent of the genes, in our body are human. The other 90 percent of cells (100 trillion to be more precise) are composed of microbes, that reside mainly in our gut, and, collectively, harbor at least 100-fold more genes than their human hosts.
Therefore, we can more specifically say that we are what our microbiome eats. Our microbiome, in turn, performs an astonishing variety of important functions, which scientists are only starting to fully understand.
When we eat fiber and resistant starches (which come only from plants), we are feeding our gut bacteria, which, in turn, produce important molecules called short-chain fatty acids. SCFAs in turn play a key role in regulating our appetite, regulating our energy metabolism, turning on and off the expression of genes, and regulating key gut hormones, and also regulate insulin sensitivity.
These effects are beneficial to our health because they protect us against obesity, diabetes, and chronic intestinal problems such as inflammatory bowel disease and colon cancer. It was pointed out in the Spring OQ that 97 percent of Americans are not getting adequate fiber in their diets. When we don’t regularly consume fiber, the beneficial bacterial colonies in our gut die off, and, in turn, the cells lining our gut (the colonocytes) literally starve. If spread out, the surface area of our gut has been estimated to be the size of a tennis court or a studio apartment.
The primary energy source for our colonocytes is the SCFA butyrate. Butyrate is formed through fermentation of fiber in our gut. The butyrate diffuses inside the cell mitochondria and drives key energy-producing pathways. If butyrate is not available, the colonocytes are deprived of nutrients for energy and resort to autophagy (a catabolic process where the cell degrades its own cellular components in an attempt to maintain energy homeostasis). Essentially, our gut lining consumes itself to maintain energy.
Scientists demonstrated that the energy-deprived state and increased autophagy was a direct result of absence of microbes through studying germ-free mice, which are raised in a pathogen-free facility and lack gut bacteria.
Germ-free mice exhibit signs of impaired colonic function, mild diarrhea, and they drink significantly more water than normal mice. Also, their colonocytes produce less ATP (energy units). The gut function of these mice can be rescued by introducing a normal gut microbiota into the mice. Scientists alternatively introduced butyrate directly onto the colonocytes of germ free mice and this resulted in a dramatic effect on cell energy production, from 30 percent to 70 percent of normal.
In another study, rats that were fed various types of short-chain fatty acids, were protected against weight gain when placed on a high-fat diet, and had better glucose tolerance and fasting insulin levels than control rats. Certain SCFAs have been demonstrated to reduce appetite in humans and other SCFAs appear to protect against weight gain. Scientists are learning that it happens through our gut microbiota regulating the metabolism of their hosts (we humans) .
Therefore, as you might imagine, because of the immense number of DNA (each with its own characteristic and on-off regulation) it’s complicated.
It’s not as straightforward as “fiber is bulky and makes us feel full.” The reality is there is an elegant and sophisticated interplay between the plants we take in, and the microbes that reside in our bodies. It’s good to be aware of this relationship and understand that we share our space, not just with those around us, but with those within us. The relationship is more than just commensal, it is mutual.
If you’re concerned about your gut biome, you can also try fermented drinks like kombucha. In Ojai, we’ve got plenty of good options: try Revel’s kombucha bar, or the kombucha on tap at Noso Vita, or look on your supermarket shelves for KeVita, an Ojai-based product that has gone nationwide.
Much like our community here in Ojai, we thrive when we function as a interconnected unit.
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