The gut-brain connection: why you need to know about it

Scientists call the pathway that connects your gut to your brain ‘the gut-brain axis’. It’s like a busy, two-way highway built of neurons (nerve cells).

Your brain and gut send messages to each other along this highway using chemical messengers known as neurotransmitters. These messengers influence how you feel, how you focus, and to some extent, how your body itself behaves.

Your digestive tract starts at your mouth and finishes, at… well… the other end. Along the way, it includes your stomach, intestines, pancreas, liver and gallbladder. All up, it’s somewhere around nine meters long, with about 800-900 folds in it.

But the bit of your digestive system we’re most interested in for this article is the gut: your stomach and intestines. This part doesn’t only digest food and then get rid of the waste when it’s done. It also plays a huge role in keeping you healthy.

Trillions of bugs (bacteria, viruses and yeasts) live in your gut. Together, they’re known as your gut microbes or gut microbiome. When you’re healthy, you’ll have anywhere from 300-500 different species living in there at any one time.

And before you freak out, the majority of these little fellas are harmless. A bunch of them are actually good for you. In fact, your body contains about 10 times more bacteria cells than human cells. That makes you naturally more bacteria than human!

Yes, of course, there are a few bad bugs too, but less than 5 per cent are harmful or cause disease. And one of the roles of the good guys is to keep those bugs in check. So really – no need to panic!

Studies have shown your gut has so many neurons in it – over 100 million of them – that scientists now call it your second brain.

Of course, it doesn’t technically have thoughts or make decisions. Although, yes, we often talk about making a ‘gut call’ or following ‘gut instinct’ on an important choice. So we recognise that something’s going on there!

But your gut ‘brain’ still functions independently, and it definitely physically influences how you feel about things. For example, your gut cells produce something like 90 per cent of your body’s feel-good hormone serotonin (more on this later).

So the link between your gut and mood is about more than just a couple of cute turns of phrase.

Your gut plays a lead role in keeping your body functioning well. The trillions of bugs in your microbiome influence your brain, heart health, immune system, mood and behaviour. They also help you to digest your food and even synthesise some important vitamins.

Basically… you’d struggle to survive and stay healthy without them.

Your gut breaks down everything you eat and drink. It absorbs every nutrient it can from every drop you sip and every mouthful you savour.

To take care of the critters in your gut, be mindful of what you eat. Enjoy fresh, healthy foods, and limit sugary, salty processed food, caffeine and alcohol.

Not only will this make all the good bugs happy and keep them thriving, but it will also help to keep the bad ones at bay.

Some of the issues that come from poor gut health are pretty obvious. They show up as digestive conditions like: 

• Crohn’s disease
• Irritable Bowel Syndrome (see below)
• Ulcerative colitis (bowel disease)

But other effects can be surprisingly wide-ranging, including:

• autoimmune disorders
• obesity
• some cancers
• sleep problems 

Your gut is a sensitive little soul. Ever felt your tummy churning when you’re stressed or anxious? So many of our feels start in our gut.

We began to talk about serotonin above. Low mood, anxiety and depression are all associated with low serotonin levels. And, as we mentioned, you don’t store most of your serotonin in your ‘head brain’. Instead, you produce and store it in your gut.

Replacing highly processed, fatty, sugary junk food with high-fibre, probiotic- and prebiotic-rich foods can help to nourish good gut bacteria. This, in turn, can help to balance your mood and improve your mental wellbeing.

Research has also linked gut health and ADHD (attention-deficit/hyperactivity disorder), showing a strong connection between the gut, brain function and behaviour.

We know that gut bacteria talk to the brain in many different ways. One of these ways is via the vagus nerve. This nerve runs from your gut to your frontal lobe: the area of your brain that controls cognitive skills like managing emotions, solving problems and judgement.

Children and adults with ADHD may have weak frontal lobes, so their gut bugs may communicate poorly with their brains. A poor connection could then cause problems for breaking down and absorbing nutrients. And without those nutrients, their gut cells will struggle to produce serotonin and dopamine (another important feel-good chemical).

To help kids and adults with ADHD, we need to put them in a good food mood and feed them yummy, healthy food and natural, sugar-free drinks.

Around 1 in 5 Australians have experienced IBS symptoms at some point in their life. It’s a mild irritation for some, but completely debilitating for others.

IBS symptoms include:

• abdominal pain
• bloating
• alternating between constipation and diarrhoea

Nobody’s 100 per cent sure what causes IBS, although health experts believe that stress, infection and diet all play parts. We also know that IBS symptoms can go crazy when your gut, nervous system and brain don’t communicate well with each other.

Most people find that particular foods set off their symptoms, although the specifics can vary from person to person. You’ll need to do a bit of detective work to figure out which foods squabble with your gut, and then avoid them.

We all know restless sleep is the pits. You’re tired all day and prone to mood swings, and you also make poor decisions and struggle to focus.

Your gut microbiome controls the hormones that help you sleep. Unbalanced hormones can lead to unsettled sleep, and, in the long run, to chronic insomnia or fatigue.

So how do you improve your gut health? The good news is that a healthy diet and lifestyle can have a major impact on how healthy and happy your microbe gut buddies are.

Here are four key ways you can build a better gut:

• Try fermented foods that contain probiotics: options include natural yoghurt, some artisan cheeses, kimchi, sauerkraut and probiotic-rich drinks like kombucha,kefir or probiotic soda.
• Eat plentyof fibre-rich, plant-based foods: load up on veggies, fruits, nuts, legumes and wholegrains to make your gut bacteria happy.
• Reduce – or,better still, avoid – junk food: sugary, salty processed and fast foods aren’t great for you or your gut buddies.
• Watch the sweet stuff: avoid refined sugars and artificial sweeteners.
• Enjoy healthy fats: gut microbes love extra-virgin olive oil.

• Eat slowly and enjoy your food: chew your food well, and don’t gulp it down. Otherwise, your gut will have to work extra hard to digest it, which can be uncomfortable.
• Stay hydrated: drink plenty of water to keep your gut happy.
• Listen to your gut: if you notice particular foods trigger IBS symptoms, you may have a food intolerance. Eliminate and reintroduce foods to find the culprit/s.

• Prioritise exercise: find time to move and be physically active every day.
• Make it intense: build up a sweat for added benefits.
• Don’t eat while exercising: in fact, don’t eat while you’re doing anything else – not even while you’re ‘on the go’ or checking emails. You can’t digest your food properly.

• Get enough sleep: as tempting as watching another Netflix episode might be, your gut buddies need you to get around 7-8 hours of rest each night.
• Switch off your screen: aim to avoid any screens (including your phone) for 60 minutes before bedtime.
• Chill out your way: find your favourite way to lower stress – try walking, yoga, meditation, getting a massage or chatting with family or friends.