Who hasn’t talked about gut feelings or going with their gut? Yet somehow, when we talk about intuition—or even when we’re feeling anxious, sad, foggy, fatigued, or forgetful—we always tie it back to the brain.
The first thing to know here is that our brains are innocent! We think of the brain as “the one that rules them all,” but, in fact, the brain is less the ruler of the body and more a reflection of the overall health of the body—especially the gut.
That’s right, the gut is thought to play such an important role in brain function that it has sometimes been called “the second brain.” Indeed, the gut produces its own neurons, neurotransmitters, immune system, and much more, just like the brain does. And, the gut and brain also work together in a millisecond-by-millisecond way so that we can function optimally.
The relationship between the gut and brain is referred to, perhaps predictably, as the gut-brain axis. When it’s in balance, things in the body and brain run smoothly. When it’s not in balance, we can become inflamed, develop autoimmunity, grow depressed or anxious, and feel compromised cognitively. Here, we’ll explore some of the different pathways through which the gut-brain axis runs the show in our body.
The many Players of the gut-brain axis
The gut-brain axis features a few major players. Here’s what to know about each of them.
1. The vagus nerve
The vagus nerve is long and meandering, running between the digestive tract and the brainstem and making many stops along the way (including in the diaphragm, heart, and throat). The nerve sends messages from the gut to the brain and vice versa, so when either is dysregulated, it can lead to a host of other symptoms. The vagus nerve modulates the parasympathetic nervous system, which controls a sense of calm sociability. When vagal nerve function is disrupted, symptoms can include abdominal pain, nausea and vomiting, digestive disruption, issues with speaking and swallowing, and depression and anxiety.
2. Immune cells
Our digestive tract is filled with immune cells, which are also found in the tonsils, special lymph nodes that line our digestive tract called Peyer’s patches, the spleen, and even the appendix (nope, it’s not just an old useless appendage but a treasure trove of immune cells and microbes that keep our gut healthy throughout our lives).
All of the immune cells in the gut communicate with other immune cells throughout the body—including microglia, which act as nurse cells to the neurons in the brain—by way of compounds called cytokines. Cytokines even cross the blood-brain barrier into the brain and activate the microglia directly. When microglia are activated, they turn from nurse cells into mama bears and can start to create a lot of inflammation in the brain. This can then make the neurons irritable and lead to symptoms such as changes in mood and cognitive function.
That’s right, your digestive tract produces neurotransmitters—and not just a few of them. In fact, your gut actually produces more neurotransmitters than your entire central nervous system. A major one is serotonin, which plays an important role in the gut itself, particularly for people suffering from irritable bowel syndrome, because serotonin is involved in digestive motility and immunity. It is also a major player when it comes to improved mood and finding calm. Other neurotransmitters produced in the gut include GABA, glutamate, dopamine, acetylcholine, and melatonin. It’s no wonder that when our gut is a mess, we feel like a mess in a slew of other ways, too.
4. The microbiome
If we’re lucky, we each have somewhere between three and five pounds of microbes that live in and on our bodies, primarily residing in the digestive tract. We want many, many different strains of bacteria to live in our guts—and the more diverse the better. This is because the more types of organisms there are, the less any one kind of organism is able to grow out of control. It’s a checks-and-balances system, among many other things.
And, it turns out that this universe of invisible microbes is responsible for more than just gut health (which is important in and of itself). It’s also responsible for brain health and a positive mood. In fact, certain strains of microbes that have been shown to support mood, ward off depression, ease anxiety, and much more—now dubbed “psychobiotics”—might just be the next generation of mental health support.
How to support an out-of-balance gut-brain axis
When your gut-brain axis is unbalanced, you can experience a whole host of nasty and surprising symptoms (remember: trouble focusing, changes in mood, inflammation, gut health issues, and the like). You can start to help this complex communication network straighten out its signals in a few key ways.
Whether you’ve taken an array of antibiotics throughout your life (as many of us have) or not, increasing the diversity of organisms in your gut helps your gut-brain axis function better. A high-quality probiotic offers an array of healthy organisms to support this, such as lactobacillus and bifidobacterium strains.
2. Vagal nerve stimulation
Humming, singing, chanting, gargling, and laughing can all regulate the vagus nerve and help recalibrate the gut-brain connection. Hot-cold showers, cold immersions, regular sauna time, and massages can also balance vagal nerve function. Though you certainly don’t have to do all of these practices daily for them to be effective, they are all most helpful when done regularly. I recommend taking some time every month or two to create a flexible but regular schedule for which practices you’ll incorporate and when, based on what you enjoy or feel most drawn to.
Adding more whole, unprocessed foods into the diet—as well as reducing highly-processed and high-sugar foods—can be very helpful in supporting a healthier gut-brain axis. Keeping a food and symptom journal for two to four weeks can also help you identify what foods may trigger particular symptoms, like digestive upset, anxiety, insomnia, and even headaches and brain fog.
4. Herbal Supplements
Certain herbs can support the gut and therefore also lead to benefits for the brain. For those with digestive discomfort, aloe vera (the inner gel only), marshmallow, or slippery elm can soothe the gut lining and allow it to heal. Bitter tonics, like dandelion or gentian, meanwhile, can improve gut motility, reducing belching, bloating, and constipation. Ginger and curcumin, finally, can help the gut manage out-of-balance inflammation.
Dr. Shetreat is a neurologist, herbologist, and author of The Dirt Cure, in which she presents a nutritional plan for getting and keeping children healthy. She works and studies with indigenous communities and healers from around the world, and is the founder of the Terrain Institute, where she teaches earth-based programs for transformational healing.