We often hear the phrase "the gut is the second brain", but what exactly does that mean? While many of us can admit to thinking with our stomachs occasionally, the brain and gut are still two very separate systems with very different functions. What they have in common is the ability to communicate.
Think of your intuition and brain as two familiar friends on the phone.
The gut is a "chatterbox" for two people, and most of the "conversation" is transmitted directly from the gut to the brain, mainly through the vagus nerve.
Now imagine the various ways that the gut and brain communicate, such as hormones, nerves, and immunity, such as phone lines.
To make the conversation a little easier, the gut and brain speak the same language in the form of messenger molecules, such as hormones, neurotransmitters, and cytokines.
What message is sent depends on many factors, including the balance of microbes in the gut.
The gut microbiome sets the ‘tone’:
Because the microbiome plays an important role in coordinating communication between the two systems, the gut-brain axis is now more commonly referred to as the microbiome-gut-brain axis. Think of the microbial balance in the gut as setting the "tone" of the conversation. If the gut flora is balanced according to the owner's needs, the conversation will be filled with "good" messages expressed in a healthy mind and body.
If the gut microbiome is out of balance (aka dysbiosis), the conversation can lead to a "bad mood" on both sides. In other words, both the gut and the brain show signs and symptoms of healthy imbalances, such as digestive discomfort, stress, and mild anxiety.
Supporting the gut-brain axis with a healthy food (and thought) diet:
One of the ways to support microbiome, gut and brain health is through diet.
It's not just about your diet, it's also about your "thinking diet."
Just like food, your thoughts need to be consumed and processed before they can be physically expressed. For example, eating a nutrient-dense diet can help keep your mind and body healthy, while eating a diet rich in junk food does the opposite.[i] So is your thinking. Excessive consumption of "junk thoughts," such as reading too much negative news, or having frequent negative conversations or arguments, can lead to physical signs of stress and tension. However, quiet rest, meditation, and nature walks can improve health.
Synbiotics to support healthy brain(s) function:
Another way to support the health of the microbiome-gut-brain axis is to supplement with synbiotics. Synbiotics are defined as a combination of probiotics and prebiotics. Probiotics are live microorganisms that provide health benefits, while prebiotics are food sources that probiotics can utilize.[ii]
Certain types of probiotics and prebiotics have been shown to support the gut-brain axis by helping restore beneficial gut bacteria and supporting healthy gastrointestinal, immune, and neurological function. Certain types of probiotics are even starting to show promising results in reducing symptoms of stress and mild anxiety.
Polyphenols, including those found in herbs such as saffron, act as prebiotics in addition to their own inherited stress-relieving properties.[iii]
We all enjoy a friendly chat!
By understanding the role of the microbiome-gut-brain axis and its importance in health maintenance, we can take better steps to ensure our guts and brains enjoy the health benefits of "friendly conversation" for years to come!
If seeking specific advice on supporting your mental or physical health, please consult your health professional.
[i] Taylor AM, Holscher HD. A review of dietary and microbial connections to depression, anxiety, and stress. Nutritional neuroscience. 2020 Mar 3;23(3):237-50.
[ii]Swanson KS, Gibson GR, Hutkins R, Reimer RA, Reid G, Verbeke K, Scott KP, Holscher HD, Azad MB, Delzenne NM, Sanders ME. The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of synbiotics. Nature Reviews Gastroenterology & Hepatology. 2020 Nov;17(11):687-701.
[iii] Thilakarathna WW, Langille MG, Rupasinghe HV. Polyphenol-based prebiotics and synbiotics: potential for cancer chemoprevention. Current Opinion in Food Science. 2018 Apr 1;20:51-7.