Why your gut is the secret to a healthy mind

Supermarket shelves laden with probiotics, magazines filled with digestive health articles, gastroenterologists giving TED talks and a book called Gut becoming an unlikely international bestseller… It’s impossible not to have noticed the rise of what was once a fairly neglected organ.

Where Freud invented the “self” in the late 1800s, spawning a century of psychoanalysis, the 21st century looks set to be one of the gut.

Forget the subconscious. It’s all about what goes on in our intestines and how this impacts the mind, or to use the scientific term—the gut/brain axis. Because the two are interlinked more closely than we might have imagined. The gut contains as many neurons (or brain cells) as a cat has in its head. And think how wily cats are. These gut brain cells are linked directly to the brain via the vagus nerve.

So the stomach has a knowingness of its own, which seems extraordinary until you pause to think about our language: gut feelings, gutsy, gutted, gut instincts, gut wrenching and butterflies in our tummy. All these colloquial phrases imply a link between our stomach and our emotions and yet, especially in the century of psychoanalysis, we tend to think of the brain being the puppeteer and the stomach simply reacting to its instructions—the mind gets anxious and the stomach knots…

But now scientists have established that it works both ways, that the stomach is responsible for a lot of what goes on in the brain and may even be the organ that’s in the driving seat: the stomach knots and the mind gets anxious, not the other way around.

“We’re beginning to realise that there’s a lifelong symbiotic relationship between gut bacteria and the brain,” says Professor John Cryan—a neuroscientist at the University of Cork. “There are more bacteria in our gut than cells in our body and these are like little factories taking food and converting it into a wide range of hormones, chemicals and neurotransmitters which can directly affect our mood, behaviour and general health.”

The bacteria that live in our gut are collectively called the microbiome, a deep dark internal forest of more than 50 trillion organisms of at least a thousand different species—a richer diversity than you would find in a rainforest!

“Strictly speaking, the gut is not actually part of the human body at all since it’s composed largely of the microbes that live there,” says TV Dr. Michael Mosley, pioneer of the 5:2 diet whose latest book The Clever Guts Diet takes us on a journey through the digestive tract (literally, since Moseley swallowed a small camera to get a good look at his own). “Advances in technology means we can now see this army of microbes which regulate our entire immune system. And understanding how they work should open up whole new avenues of treatment for allergies, autoimmune diseases as well as a range of psychiatric conditions. It’s an incredibly exciting new development.”

And yet, this “new” area of scientific exploration has its roots in the sixth century BC when Hippocrates, the father of medicine, suggested, “all disease begins in the gut.” He had no proof, but his gut instinct is proving almost correct. Not all diseases stem from the gut but many of them seem to.

Fast forward to the beginning of the 20th century when Russian immunologist Élie Metchnikoff, advanced the “crazy” idea that people in parts of rural Bulgaria lived longer because they ate a lot of fermented foods containing lactic acid bacteria, the so called “good bacteria” that’s always talked about in yogurt adverts.

Metchnikoff won the Nobel prize in 1908 for his work in immunology but his ideas about gut bacteria were largely forgotten about, except in Korea where his face appears on yogurt drinks. But some of the work done by John Cryan and his team in Cork now supports his hypotheses. “Our studies showed that in a group of elderly people health outcomes and frailty in particular correlated with the diversity of their microbiome, suggesting that the secret to healthy ageing may indeed lie in the gut.”

Where once no Woody Allen film was without reference to a shrink, these days American sitcoms are more likely to nod to food intolerances and digestive disorders. And, given the gut may hold the key to the preventing a whole host of diseases and even help promote longevity, it’s hardly surprising that the new docs on the block are gut doctors.

“I think this interest in the gut has been forced upon us by the exponential rise of digestive disorders, as well as autoimmune diseases and chronic conditions linked to gut health that have become omnipresent in our society.” Eve Kalinik is a nutritional therapist and author of Be Good To Your Gut. She also runs the Guardian masterclass: Happy Gut, Happy Mind. Her own interest in gut health stemmed from a damaged immune system caused by a recurrent kidney infection and an associated overuse of antibiotics. She looked to her Polish father, whose diet included a range of fermented vegetables and the almost ubiquitous Eastern European sauerkraut. She then began to devise recopies designed specifically to improve gut and—in the process—overall health.

“The gut influences so much more than digestion, including managing immune system functions, producing anti-inflammatory substances and it plays a significant role in cognitive health too. The gut-brain connection is one that’s extremely powerful and the gut is the ONLY organ in the body that can function irrespective of the brain.”

So it’s important to look after it. You are what you eat, goes the old adage and a diet rich in fruit and veg with some fermented foods is widely believed to be the best way of increasing the diversity of gut flora.

The trouble is that in the second half of the 20th century we started eating heavily processed junk food, taking antibiotics, and killing off vast swathes of our microbiomes in the process.

“Our guts,” says Michael Mosley are “almost as depleted as the Amazon rainforest and this has led to a rise in a range of conditions ranging from allergies and autism to diabetes and rheumatoid arthritis.”

The market has been quick to jump on the mircobacterial bandwagon—producing a range of probiotics whose effects are largely unproven. Scientists have only been able to culture about five per cent of gut flora and are still trying to sequence the rest.

“It’s still early days,” says John Cryan from Cork University. “But we have begun to appreciate the power of microbes and are working towards harnessing them to improve health and tackle diseases. More studies are needed on probiotic strains, prebiotics and even faecal microbiota transplants.”

The latter, in layman’s terms is a poo transplant which, disgusting as it sounds is already used for treating the effects of C difficile a bacteria that can infect the bowel, causing diarrhea and typically affecting people who have recently been treated with antibiotics. One wonders what Freud would have made of all this. He told us the proximity of the anus to the genitals, was the source of much if not all human neurosis and yet, ironically, it could be the “crapsule” that turns out to be the cure for many of them!

The secret to happiness may not be buried in your subconscious at all, but deep inside your gut.