Why You Should Listen to Your Gut – The Gut Brain Connection
by Catherine Morris | July 29, 2020, updated almost 2 years ago
Have you ever had a gut feeling that something was wrong? Been told to follow your gut instinct? Felt a strong gut reaction to someone? English is full of weird idioms that make zero sense, but these ones actually have roots in sound science.
You might think your digestive system is simply toiling away to process your last meal, independent of everything else going on in the body, but the reality is more complex. If you think of the body as a machine and the brain as the control centre, the guts are the engine, powering and supporting all other functions.
Hippocrates claimed—“All disease begins in the gut”, and science is proving him right. A healthy gut means a healthy body, and not just physically – medical research is now drawing a strong link between what's going on in our heads and what's going on in our bellies, with exciting implications for mental health treatment.
If you're wondering why your bad mood has been unshakable, or why you have brain fog, or you’re looking for ways to support your addiction recovery, you might need to look below your neck.
You are riddled with bugs. Don't take it personally, so is everyone else. Every human comes with their own internal and unseen community of microorganisms, known as our microbiome, and our very survival depends on these tiny squatters. These ‘bugs’ number between 10 and 100 trillion per person.
Primarily composed of bacteria, fungi and viruses, these inhabitants don't sound like something you'd want to share your body with, but they perform a range of vital functions from supporting our immune systems, to getting nutrients to our cells and fending off pathogens.
We're born sterile, but we begin to develop our microbiome almost immediately after birth, picking up a few bugs during birth and rapidly accumulating more in the first few years of life. By the time we hit three our microbiome is largely stable, but it does fluctuate throughout our lives, and is affected by diet, stress, drugs, and other factors. Everyone's microbiome is unique and, just like any other bodily system, our friendly bugs thrive when they're tended to, and deteriorate when neglected.
While every organ has its own microbiome, the gut's (i.e. the organisms present in the gastrointestinal tract) generally gets all the attention as this is where it's most concentrated. If the body were a country, the guts would be the capital city – a buzzing urban sprawl that never sleeps.
The organisms colonizing the intestines have been the subject of intense study in recent years as medicine tries to harness their potential to treat disease, and predict future health. There's still much that's mysterious about the microbiome, which leads some scientists to refer to it as 'biological dark matter', but contemporary research has made some important discoveries.
The Gut-Brain Axis
We tend to think of our thoughts and feelings as coming from one of two places – our heart or our head, but there's a third player at work. Your gut is so integral to your thinking that it's best thought of as the second brain, and is often referred to as exactly that.
Why? Your brain and your gut are in constant communication. Scientists have labelled this connection the 'gut brain axis' (GBA). The GBA is a highway where your central nervous system and enteric nervous system intersect and regulate other parts of the body such as your immune and endocrine systems. Most of the chatter between the gut and the brain takes place via the vagus nerve, a crucial player in the GBA. The vagus nerve sends signals between the brain and the gut, and vice versa.
Your brain and gut may be BFFs, but what are they saying to each other? The messages from the gut to the brain are mainly about the health of your internal organs and what's going on below the neck. The brain mostly just tells the gut about its stress, emotional trauma, and other negative feelings—everyone has that friend, right?
Remember the last time you had to do something that made you nervous? You probably felt butterflies in your stomach, your gut might've clenched and you may have described it as stomach-churning. All that anxiety was being processed by your brain and sent down the super highway of the vagus nerve.
If your gut bacteria isn't in the right balance, or there's some deeper digestive issues at play such as Crohn's Disease or IBS, that biological stress is sent to the brain – influencing your mood and, in severe cases, causing depression.
How Your Guts Affect Your Mood and Mental Health
We're used to thinking our moods come only from external factors – I'm irritable because I got stuck in traffic; I'm happy because I got a promotion; I'm miserable because I had a fight with my partner.
What happens to us is important, but equally important is what happens inside of us. So much of our mood is directed by our hormones – serotonin, oxytocin, and dopamine to name a few – and where are those hormones produced and regulated? Yep, the gut.
If these are out of kilter, bad moods and fuzzy thinking follow. In severe cases, it can go beyond a bout of the grumps—what happens in the gut is linked to neurological disease, and psychiatric disorders.
Feeling it in Your Gut
A whopping 90 percent of the body's serotonin – the 'happy' hormone – is produced in the digestive tract, so it's no surprise that stress, depression and anxiety often start there. Low serotonin causes both digestive and neurological symptoms. A third of people with depression report chronic constipation. Altering the gut biome can banish both.
In a study on obese mice, researchers from the Joslin Diabetes Center found that they could reverse depression and anxiety in the rodents by putting them on a course of antibiotics. They concluded that altering the gut biome through diet could alter negative behaviour. Lead researcher C. Ronald Kahn had this to say—
“Your diet isn't always necessarily just making your blood sugar higher or lower; it's also changing a lot of signals coming from gut microbes and these signals make it all the way to the brain. [Depression and anxiety] are driven to some significant extent by the gut microbiome,”
It follows that probiotics might have the potential to treat these conditions, and further study has confirmed this. In a McMaster University study study, people with IBS reported depressive symptoms lifting after a course of probiotics, with improvements seen at double the rate of the placebo group. In some cases, probiotics are just as effective as standard antidepressants – lowering cortisol levels, and reducing depression as effectively as the commonly prescribed medications Citalopram, and Diazepam.
You can also reduce your stress and anxiety by tweaking your gut biome. A review of recent medical literature shows that probiotics and dietary changes have around an 86 percent success rate in alleviating anxiety.
Regardless of whether you have a mood disorder, you should probably still be eating for better gut health. Healthy intestinal flora doesn't just affect how you feel—it affects how you think. Getting the right balance of bacteria can potentially improve your memory, slow neurological decline related to aging and even make you smarter.
The Gut-Brain Axis, Psychiatric Disorders, and Addiction
As our understanding of serious mental health disorders like schizophrenia has evolved so too have the treatments. Today, sufferers are likely to find themselves on a course of antipsychotic medications and/or mental health therapy. However, research indicates that nutrition should be on the table as part of a wider treatment strategy that acknowledges the crucial role of the GBA.
Schizophrenics are more likely to suffer from gastrointestinal barrier dysfunction – a problem that hyper-activates the immune system and causes inflammation – and food sensitivities, than the average population. A gluten-free diet often helps these patients manage their digestive symptoms.
Another simple therapeutic remedy is that old favorite, probiotics. It's still very much an emerging field of study, but a 2019 report, which examined the effects of supplementation on schizophrenics and people with bipolar disorder, states— “Probiotic supplementation was shown not only to alleviate gastrointestinal complaints, but also reduce symptom severity, rehospitalization rates, and cognitive improvement.”
The gut can be an ally in treating psychiatric disorders, but it might also be involved in their origins. It's now widely known that certain mental health disorders have a hereditary, or genetic component. Schizophrenia, depression, bipolar disorder, and even alcohol addictions tend to run in families. Know what else runs in the family? Your microbiome. You share more than just hair or eye colour with your family – the composition of microbes in your gut is more likely to resemble that of your parents or siblings than the gut biome of a random stranger on the street. This has led some scientists to theorize that the genes which play a role in inherited psychiatric conditions might just begin in the microbiome. With this in mind (pun intended) there's a real possibility that future mental health treatment will blend epigenetics with GBA research to hone in on delivering customised, holistic remedies.
Science has already begun leveraging new knowledge about the gut to treat one of the worst mental health disasters in recent history – the opioid crisis. A team from the University of Alberta is now exploring this promising avenue of treatment after noticing significant differences between the microbiome of morphine-addicted mice compared to mice who were never exposed to opioids. More recently, the University of California discovered that gut microbes change the way the brain reacts to drugs… at least, in rats.
“Not only does this study suggest gut microbes may play a role in drug addiction, if we find similar effects in humans it may change the way we think about co-prescribing antibiotics and painkillers. The way a person's gut microbes are affected could make them more or less sensitive to the opioids,”
Commented researcher Olivier George, associate professor of psychiatry at University of California San Diego School of Medicine.
It's not the first time researchers have hypothesized that addictions begin in the intestines, but the science is so new that the task now is to keep building the data, and one day hopefully replicate these results in humans. In 2018, the National Institute on Drug Abuse kickstarted a US $4 million study to explore the role of the microbiome in substance abuse. The project, which runs until 2023, will focus primarily on cocaine, and will examine how dopamine levels, genetics, and the gut all play a part in addiction and withdrawal.
Neurological Disease and the Microbiome
Neurological diseases with a genetic link include Alzheimers, dementia, Parkinsons, and ALS, and by now you won't be surprised to hear that these have a gut connection too.
- An unhealthy gut biome appears to increase the risk of developing Parkinson's disease. A Mediterranean diet, that includes lots of fibre can help reduce that risk.
- The dysfunctional protein 'clumping' and inflammation in the brain that are the hallmarks of Alzheimers, Parkinson's and ALS are likely triggered by proteins made in the gut.
- Changing the gut biome (through antibiotics or a fecal transplant) of mice carrying the ALS gene also changed the way the mice manifested the disease – alleviating symptoms or preventing them altogether.
With so much solid research out there about the GBA, it's no wonder that pharmaceutical companies are looking to cash in on this potential health goldmine. It's not glamorous work by any means, but the race to develop neurological treatments from fecal matter is one that many big name healthcare firms are clamouring to win. With regulation trailing behind, and health agencies taking a dim view of these types of therapies, it may be years before the first 'gut bug drug' hits the market.
In the meantime, there's plenty of opportunity for the average person to help themselves simply by adopting some gut-friendly dietary and lifestyle changes.
Building a Happy, Healthy Gut
Chad Grant co-founder of Anabolic Aces Health Consulting provides customised health coaching and sees many clients with both neurological and digestive symptoms—
“A lot of people present with gut issues and corresponding mental health issues, that's definitely a pattern we've seen in our practice. We work with everyone on the gut as part of their treatment plan. The gut is one of the big pillars of health. It is everything.”
Anabolic Aces uses comprehensive blood and stool lab testing to pinpoint health issues, and develop specific plans for their customers. A gut health consultation typically involves testing the DNA composition of the microbes in the gut to get a good idea of a client's microbiome. “We are the private detectives of the health world. There's a lot in the biochemistry. We combine the data, science and natural health to work with the body,” says Grant.
Once a client knows their specific issues, they can start building that baseline of 'good' bacteria that can help resolve not just digestive complaints but also depression, anxiety, and that nagging addiction to sugar. Grant advises clients with gut issues to avoid inflammatory foods such as sugar, gluten, corn, nightshades, and dairy, but stresses that it's important to be armed with data before embarking on a new health regime.
“There is a lot of emotional resistance to changing some foods, even with people who are pretty savvy about health. People sometimes try elimination diets but it's hard to do that permanently. People get frustrated and start adding things back in, but without the data you could be adding back in the wrong things.”
Aside from the obvious bacteria boosters like fermented foods, Grant recommends a whole food, organic diet for optimized gut health. When it comes to supplements he says digestive enzymes and gut-soothers like marshmallow root, aloe, and slippery elm can be helpful. Some people may also benefit from Intermittent Fasting – where they reduce their eating window or eat just one meal a day. Grant says— “Fasting can help with gut health because it gives the digestive system a break. There are two modes in the body – rest and digest. The gut uses that time for detox and restoration.”
Then there's the basics of good health – get quality sleep, move more, soak up the sunshine, and reduce stress. Avoiding toxins such as plastics, water contaminants, pesticides, and medications like NSAIDs and other painkillers can also help, according to Grant, who encourages people to strive for better gut-friendly habits, but not to get discouraged if they fall short—
“We tend to start with the basics with most people. I tell them to do the basics really well every day as opposed to trying to make up for it on weekends by running a marathon. We all cheat now and then. No-one is perfect. I tell people to try to hit 99 percent but when you don't, it's okay. It's a self love thing.”
With so much buzz around bacteria lately, Grant is optimistic that the wider health discussion will change for the better—
“More conventional medicine is talking about gut health now, and I'm really hopeful it is going to become more mainstream. As time goes on, and there is more research into the gut brain connection, I think people will start looking at some of those other more nuanced things like digestion and lifestyle choices.”
If you’re looking to improve your gut health, talk to one of Which Doctor’s nutritionists, naturopaths, dieticians or health coaches today. Those seeking a more data-driven approach, can book a functional nutrition or gut health consultation with Anabolic Aces co-founders Chad Grant or Natasha Hawthorn here.
Catherine Morris is an award-winning journalist with a bad case of wanderlust and a passion for all things health and wellness. Originally from Northern Ireland, she worked as a news and feature writer for media outlets in the UK, South Africa, France and the Caribbean before settling in Canada. Catherine now lives in Alberta with her husband and rescue mutt and spends her time happily exploring the great outdoors with both.