Our Gut-Brain Axis ~ and the role of probiotics and prebiotics
“We are nesting in your intestine and strolling through your colon; for that, you should be thankful.” anonymous good gut bacteria.
In a 2004 research experiment, scientists sterilized mice by removing all their microbiomes, including those found on the skin, in the mouth and G.I. tract.
A control group of mice had a normal microbiome. When tested for cognitive abilities, the sterile mice performed poorly compared to the control group – additionally, the sterile mice presented with many health problems, both physical and cognitive.
The mice experiment demonstrates the advantages of co-evolving with beneficial bacteria but warns about how antibiotics can devastate a healthy gut biome. If you are required to take a regimen of antibiotics, research suggests you also consume prebiotics and probiotics to maintain your microbiome.
There may come a time when manipulation of the gut biome can replace some uses for antibiotics. However, we are not there yet – more studies are needed about our individual floral colonies and how they affect our health.
We are in the midst of a paradigm shift in how we regard our microbiome. Science has demonstrated conclusively that we are only now beginning to understand the essential role of our colonies of bacteria living within a symbiotic relationship.
These tiny creatures are so vital that their gene expression has become one with ours. If we were told that bacteria made crucial decisions about our gut health a decade ago, we would have rejected it as pure BS.
And what we are learning about our gut biome may reduce many common diseases, including irritable bowel syndrome, obesity, Parkinson’s disease, colon cancer and even autism.
In the last episode of For Your Consideration, we discussed the composition of our gut biome. Our four to six pounds of microbiome found throughout most of our body are in much greater abundance in our gut, primarily in the large intestine and colon.
We also learned that, although most of our gut bacteria are friendly and beneficial, many pathogens lurk among the good bacteria. The two are enemies, but the good guys almost always win if you have a healthy gut biome.
How do we maintain a healthy gut biome? Please read on.
If your gut is happy, your brain is happy
The previous sentence is true, but how does the brain know what happens in our G.I. tract?
It is not an exaggeration to say that a war is going on in our gut.
You may want to think of the complex relationship between your gut and brain as a sort of cold war in a near-perpetual state of détente: if you have cultivated a healthy biome, that is.
Would you have ever imagined that your physical and mental well-being relies on trillions of gut bacteria? Probably not!
We’ll begin by discussing the finely tuned relationship between our brain and gut called the Gut-Brain Axis. We’ll save the opaque world of probiotics for last and expound further on the need for a healthy diet that includes prebiotics and probiotics.
The good news is that the 300 to 500 different species of bacteria in our gut are overwhelmingly friendly when balanced in such a way as to maintain homeostasis or physiological balance.
Over 100 trillion of these tiny soldiers are protecting us – that’s more than all of the stars in our Milky Way Galaxy.
The good bacteria, until recently our unacknowledged best friend, help us digest food, fight harmful bacteria, and affect our mood through bi-directional communication with the brain.
These microbials help regulate everything from how we feel to the efficacy of our immune system.
When your gut talks, your brain listens
The gut, or G.I. tract, comprises our esophagus, stomach, intestines and colon. Various specialized species of bacteria are found throughout the gut.
The human gut is often referred to as the second brain; some scientists contend it was our original brain.
There is a direct connection between the gut and the brain. And more importantly, this bi-directional communication between the gut and brain is stimulated by bacteria.
Close to 90 percent of communications arise from the gut and travel through the vagus nerve to the brain. The vagus nerve is second only to the spinal cord in size and function.
Our gut bacteria can create chemicals that bind to certain parts of the intestine lining. This binding results in neurotransmitters that speak directly to the brain.
When this information from our enteric nervous system (gastrointestinal tract) reaches the central nervous system, the brain releases hormones that affect our mood.
When you have a tummy ache or indigestion, our gut-to-brain communication stimulates a chemical cascade to relieve discomfort. Our gut biome is a bi-directional source of vital information between the gut and the brain, aka the Gut-Brain Axis.
“Let food be thy medicine, and medicine thy food.” Hippocrates
Although we are born with a full complement of microbials from our mother, we soon begin cultivating our own microbiome. This can be good or bad, depending on what we eat.
But what happens when our gut microbiome goes awry and bad things happen in our G.I. tract?
A procedure called fecal microbial transplant (FMT) is not new. The first recorded use of a fecal transplant was in China more than 1,700 years ago, in which donor stool was implanted in a patient.
This unusual treatment can be effective for many gut diseases, including the dreaded infection, Clostridium difficile, or, as it is better known, C. diff.
There are some surprises resulting from FMT. In one such case, a mother suffering from chronic gut distress was given a fecal transplant with stool from her daughter.
The mother was naturally thin, while her daughter was moderately obese. Following the procedure, which successfully alleviated her gut problems, the mother also became obese.
Why?
We each have a gut biome customized to our diet. If we eat too much junk or processed food, we create a feedback loop in the gut-brain axis in which the brain releases dopamine. Dopa-mine is a feel-good hormone that causes us to eat more poor-quality food.
To create a healthy gut biome, we must eat healthy food, something called prebiotics. Prebiotics are foods containing indigestible matter we call roughage or fiber.
When we eat things like broccoli, beans, popcorn, and other high-fiber foods, we encourage the growth of good bacteria that consume the roughage and help digest the food for our benefit.
Foods with high fiber content cause the release of a hormone called serotonin that regulates memory, sleep, appetite and mood. The more you eat healthy foods, the better your overall health.
We can easily recognize that many of our health problems result from diet. We really are what we eat. Unhealthy food equals a poor gut biome, and good food creates a healthy gut. It’s just that simple.
So, what’s the big deal about probiotics?
First, there’s a huge market for probiotics; globally, we spent approximately $58 billion (about $180 per person in the U.S.) on probiotic products in 2021 alone.
When consumed as a supplement in pill or capsule form, we have no idea if the cultures claimed to be in the product are even alive. Like most dietary supplements, there are no FDA regulations on quality or consistency, so it is a crap shoot as to their value.
On the other hand, many foods contain various strains of probiotics, and humans have been consuming them for thousands of years. Their use results in improved health, but until recently, the reason was unknown.
The most familiar fermented foods that naturally contain probiotics, or have probiotics added to them, include yogurt, kefir, kombucha, sauerkraut, pickles, miso, tempeh, kimchi, sourdough bread and some unpasteurized cheeses.
I recently opened my refrigerator to check the listed ingredients in my probiotic foodstuffs. My Greek yogurt did not list specific strains of bacteria; the container just said “cultured skim milk.” The label also said the skim milk was pasteurized – did they do this before the bacteria was cultured or after; it didn’t say.
My bottle of kefir, an ancient soured milk drink, listed no less than 12 strains of bacteria – all with long and hard-to-pronounce Latin names like S. diacetylatis and L. rhamnosus.
According to Livestrong, my homemade sauerkraut contains four species of probiotic bacteria. Unless stated otherwise on the package, store-bought kraut is pasteurized, so it has no live bacteria – the manufacturers killed it. I use my homemade kraut as a cold side dish because cooking destroys the little critters.
We are buying or making probiotic foods, of which we have yet to learn what specific health benefits they confer. Trying to mitigate a particular health problem through these foods is the medical equivalent of throwing spaghetti on the wall to see what sticks.
The study of probiotics will eventually determine which species of bacteria target various pathogens, virus-es and other diseases. In the very near future patients may be prescribed a compounded cocktail of gut flora to improve the efficacy of the gut microbiome.
However, we aren’t there yet. That said, consuming probiotics will help maintain a healthy gut microbiome, and the worst that can happen if you eat a range of probiotic foods is that you may get diarrhea.
My advice is to examine your current diet. If you are not currently ingesting at least a modicum of prebiotics and probiotics regularly, you may want to change your ways for better health.
Eat healthy, and give those good bacteria a pat on the tummy.
Ken Springer
ken1949bongo@gmail.com