We blame butterflies in our stomach for that feeling when we walk into a job interview.
But as it turns out, our gut-brain axis is the one at work.
Scientists believe that not only is it responsible for that ‘gut feeling’ we get, it’s also responsible for sending messages to the brain that influence obesity, depression, appetite dysfunction, and arthritis.
And these messages travel faster than the blink of an eye.
In this article, we explore the connection between the gut and the brain.
We look at what it is, how to improve brain gut connection, and why we should be doing it.
How Are The Brain and Gut Connected?
Scientists used to believe that communication between the brain and the gut happened through our hormones. Recently, research at Duke has proved otherwise.
The gut and brain are physically connected through millions of nerves, including the vagus nerve. These nerves act as a direct gut brain connection, and send signals in both directions.
The health of this connection, as it turns out, is paramount to how the brain and the gut talk to one another.
Stress, as an example, inhibits signaling between gut and brain, and causes gastrointestinal issues.
Irritable Bowel Syndrome (IBS) has been linked to reduced function of the vagal nerve.
The journey from gut to brain
You’ve got a microbiome living in your gut. It’s a good thing—a population of good and bad bacteria that maintain balance in your gastrointestinal (GI) tract.
When the microbiome’s happy balance is disrupted, however, the immune system overcompensates.
If the bad bacteria get out of control, your immune system sends out danger signals. If your microbiome is unable to balance itself, the immune system can trigger inflammation.
Inflammation has a proven link to several brain disorders—Alzheimer’s disease, depression, dementia, and schizophrenia.
The bacteria that live in your gut also release other chemicals as they feed.
They produce butyrate, propionate, and acetate, which reduce appetite. Conversely, if there isn’t enough food (more about this in Prebiotics) for the bacteria, it can’t generate enough of the chemicals to reduce appetite.
This is where the gut-brain axis is linked to appetite disorders and obesity.
The effects of the gut-brain axis reach back to early life, too. Intestinal infections can damage the mucosal membrane in the GI tract of a child, which disrupts the messages traveling along the gut-brain axis. The outcome: a negative impact on normal brain development.
Antibiotic use and poor diet can also have a negative effect on the mucosal membrane.
Neurotransmitter Connection between the Gut and Brain
The chemicals that link your gut to your brain along the gut-brain axis are called neurotransmitters. Your neurotransmitters control your emotions, and specifically feelings of happiness, fear, anxiety, and sadness.
And it turns out both these neurotransmitters are produced in your gut, too.
This is why you feel all that excitement, fear, and anxiety in your gut. It is a literal ‘gut feeling.’
It also explains how the gut communicates to the brain when it has eaten (or over-eaten), and why a damaged connection can increase the drivers behind obesity, eating disorders, and appetite dysfunctions. A healthy connection between gut and brain could also be the key to learning how to train your brain to crave healthy foods.
The basis of our knowledge on the connection between gut and brain stems from two studies.
One, conducted at Duke University in 2010 by Diego Bohorquez, established that cells found in the gut had synapses—much like are found in the brain.
He wondered if these cells—named enteroendocrine cells—could talk to the brain the way neurons do. Once he established that the signals would need to be sent via the vagus nerve, he used a fluorescent rabies virus to test his theory in mice. Injected into the colon of the mouse, the virus was communicated from the enteroendocrine cell to the vagal neurons, and carried to the brain.
The second study—which was led by Ivan de Araujo of Icahn School of Medicine—used lasers to stimulate neurons found in the gut of mice. The stimulation increased dopamine levels in their brains.
Araujo says this explains how severe depression can be treated by stimulating the vagus nerve.
It also explains why eating makes us feel good. The neurons found in the gut react similarly to the reward neurons in our brain. If the neurons are similar, it makes sense that the pleasure response is similar.
Now that we’ve established the connection between the gut and brain, how do we take maintain it?
Next, we’ll examine how changing your gut bacteria can influence your brain health.
Probiotics, Prebiotics, and the Gut
Learning how to improve brain gut connection is all about good bacteria.
The first step should focus on diet.
Including probiotic and prebiotic foods will support good microbial health and restore gut balance. It’s important to make sure both are included in your diet.
Probiotics are good bacteria for the gut. Prebiotics contain fibers that are an excellent food source for the probiotics. We can examine each member of the microbiome power couple separately.
Probiotics are live bacteria that need careful processes to thrive. Probiotic foods stem from a fermentation process that allows good bacteria to thrive. Cooking or processing foods that contain probiotics destroys their efficacy. Many probiotic foods need to be stored at cool temperatures in order to be most effective.
A study on mice showed that when they were given certain probiotics, they produced more GABA, and exhibited lessened signs of anxiety and depression.
Probiotic foods and beverages options include:
- Apple cider vinegar (with the mother)
- Cottage cheese
- Plain, unsweetened yogurt
Prebiotics aren’t living organisms. They sit in the GI tract, where their fibers can host probiotics. As the probiotics eat away the prebiotics, they are converted into beneficial chemicals within the digestive system.
These chemicals include short-chain fatty acids (SCFA). Butyrate, propionate, and acetate—the appetite suppressants which we examined earlier—are examples of these.
Prebiotic foods include:
- Oats (except quick oats, which are overly processed)
Although probiotic supplements inundate the market, scientists are still not clear on what kind of probiotics are best. If you think a commercial supplement could be better for you than eating probiotic foods, you should speak with your doctor.
Fermented Foods and the Brain
Fermenting foods has a long history. Food fermentation was born out of necessity—to improve shelf-life, edibility, functionality, and overall safety of foods. It also improves the nutrient profile in many foods.
Some nationalities eat more fermented foods than others, but fermentation is playing a bigger role in the modern diet. Fortunately, research has also uncovered that one of the benefits of fermented foods are their ability to influence brain activity. One month-long study into healthy women who consumed fermented milk products showed heightened activity in the parts of the brain that control emotion and sensation.
There are many foods we can use to improve the connection between our gut and our brain. Fermented foods, probiotics, and prebiotics all play a role in supporting our gut-brain axis.
In addition, omega-3 fatty acids, polyphenol-rich foods, and a high-fiber diet can help heal damage to the microbiome and mucosal membrane.
By paying attention to your internal balance and the foods you eat, you can nurture your gut-brain connection and improve all areas of your gut and brain health.