Does gut health affect brain health?
There is a reason why phrases like ‘gut feeling’ and ‘trust your gut’ have become clichés. For centuries, doctors have observed the link between patients’ gastrointestinal issues and their mental and emotional health. But until recently, there wasn’t much scientific evidence to back up those clinical findings.
Recent research into the gut-brain axis (GBA) is exploding. Every day, studies are revealing the many ways these keys systems are connected, along with a whole host of treatment strategies that address that relationship. It is becoming clear that clinicians addressing mental/emotional challenges must consider the gut and vice versa.
How are the gut and brain connected via this Gut Brain Axis?
These two organs are connected both physically and biochemically in a number of different ways. Neurons are cells found in your brain and central nervous system that tell your body how to behave. There are approximately 100 billion neurons in the human brain. Interestingly, your gut contains 500 million neurons, which are connected to your brain through nerves in your nervous system.
The vagus nerve is one of the biggest nerves connecting your gut and brain. It sends signals in both directions. For example, in animal studies, stress inhibits the signals sent through the vagus nerve and also causes gastrointestinal problems.
Similarly, one study in humans found that people with intestinal challenges (sometimes referred to as IBS, IBD, Crohn’s disease) had reduced vagal tone, indicating a reduced function of the vagus nerve.
The vagus acts as a pathway between the two organs, both sending and receiving signals.
How else might these two organs affect each other?
The Gut-Brain Axis: Neurotransmitters
Your gut and brain are also connected through chemicals called neurotransmitters. Neurotransmitters produced in the brain control feelings and emotions. For example, the neurotransmitter serotonin contributes to feelings of happiness and also helps control your body clock. Interestingly, many of these neurotransmitters are also produced by your gut cells and the trillions of microbes living there. A large proportion of serotonin is produced in the gut.
Your gut microbes also produce a neurotransmitter called gamma-aminobutyric acid (GABA), which helps control feelings of fear and anxiety. Studies in laboratory mice have shown that certain probiotics can increase the production of GABA and reduce anxiety and depression-like behavior. People working in this field are learning to recognize the sheer volume of neurotransmitters in the gut and that there may be more than in the brain.
The trillions of microbes that live in your gut also make other chemicals that affect how your brain works.
Just as the brain is an organ and the liver is an organ, integrative practitioners are learning to see the gut ‘microbiotia’ as an organ in and of itself. It interacts with the central nervous system (CNS) by regulating brain chemistry and influencing neuroendocrine systems (nervous system/hormone system) associated with things like the stress response, anxiety, memory function and so much more.
The Gut-Brain Axis: Gut Microbes Make Other Chemicals That Affect the Brain
The trillions of microbes that live in your gut also make other chemicals that affect how your brain works. Gut microbes also metabolize bile acids and amino acids to produce other chemicals that affect the brain.
When we used to think about probiotics, we’d focus on things like what’s the delivery form, can they survive the stomach acid, how potent must they be. Now we’re hearing more about psychobiotics, postbiotics and other therapeutic options for targeting the microbiome to support both physical and mental health.
What other connections exist between the gut and the brain?
The Gut-Brain Axis: Gut Microbes Affect Inflammation
Your gut-brain axis is also connected through the immune system. Gut and gut microbes play an important role in your immune system and inflammation by controlling what is passed into the body and what is excreted. There are inflammatory toxins made by certain bacteria, which can cause inflammation if too much of it passes from the gut into the blood.
This is often referred to as ‘leaky gut, when the gut barrier becomes porous, or a valve within the intestinal tract is dysfunctional, allowing bacteria, yeasts and other essential ‘intestinal microbes’ to cross over into the blood.
Inflammation and high levels of these microbes in the blood have been associated with a number of brain disorders including severe depression, dementia and schizophrenia.
What foods, in addition to taking ‘biotics’ help the gut-brain axis?
A few groups of foods are specifically beneficial for the Gut-Brain Axis. Here are some of the most important ones:
- Omega-3 fats: These fats are found in oily fish and also in high quantities in the human brain. Studies in humans and animals show that omegas can increase good bacteria in the gut and reduce risk of brain disorders
- Fermented foods: Yogurt, kefir, sauerkraut and cheese all contain healthy microbes such as lactic acid bacteria. Fermented foods have been shown to alter brain activity.
- High-fiber foods: Whole grains, nuts, seeds, fruits and vegetables all contain prebiotic fibers that are good for your gut bacteria. Prebiotics can reduce stress hormone in humans.
- Polyphenol-rich foods: Cocoa, green tea, olive oil and coffee all contain polyphenols, which are plant chemicals that are digested by your gut bacteria. Polyphenols increase healthy gut bacteria and may improve cognition.
- Tryptophan-rich foods: Tryptophan is an amino acid that is converted into the neurotransmitter serotonin. Foods that are high in tryptophan include turkey, eggs and cheese (however most cheese on the market today is full of artificial coloring, and has been processed in such as way as to make it almost indigestible to most people. Raw cheeses that have not been so processed are much easier to utilize. Raw goat cheeses are even better than those coming from cows).
Here at Synergetics Health & Wellness, we are working with the Gut-Brain Axis everyday, explaining how an individual’s health situation may be at least partially a product of the dysfunction of the gut-brain axis and what can be done to help address it.