If you’ve ever had an upset stomach when feeling anxious, you might have wondered if the two were linked. Research has shown that there is indeed a connection between the gut and the brain – and it’s what’s known as the gut-brain axis. Both organs communicate with each other through the central nervous system and chemicals called neurotransmitters, linking intestinal functions with emotional ones.
It’s an area of continuing research, but with the gut and the brain being so closely linked, it’s no surprise that taking care of our gut and our digestive system can, in turn, improve our mental health. And, there’s one key factor that determines how healthy our gut is – our diet. To understand how to eat our way to a better mood, first, we need to understand a little bit more about the gut microbiome.
What is the gut microbiome?
The gut microbiome simply refers to the trillions of microbes that live inside our intestines. Most are what we would consider good bacteria, while others are potentially harmful. The good microbes have a number of functions – they break down food, help to reduce inflammation, manufacture vitamins, and boost our immune system by training it to fight off infections.
When we don’t have enough good bacteria in our gut, the harmful bacteria can thrive. This is what’s called a bacterial imbalance, and it can cause all sorts of conditions and diseases, from obesity and irritable bowel syndrome (IBS) to diabetes and even cancer. An unhealthy gut will actually send distress signals to the brain, too, which can lead to feelings of stress and anxiety.
In fact almost 70% of the entire immune system is housed in the gut. Hence taking care of what we eat is crucial as the microbiome plays such an important role in our physical and mental health, that some consider it to be an organ in its own right.
So, how do these good microbes thrive in our gut? The answer lies in probiotics and prebiotics.
Probiotics and prebiotics
Together, probiotics and prebiotics contribute towards a healthy gut microbiome. But what are they, and what’s the difference between the two?
Probiotics are living strains of bacteria that simply add to the population of good bacteria in the gut. They occur naturally in certain foods, like pickled vegetables, kimchi and sauerkraut. Supplements like probiotic yoghurt drinks are also available.
Prebiotics, on the other hand, are the food that feeds the good bacteria, stimulating their growth. This food – or fuel – comes in the form of specialised plant-based fibre. It’s found in foods such as bananas, onions, beans, apples and oats, to name just a few. Plus, fibre supplements like prebiotic powder can help you increase your intake.
The third, lesser-known players in the gut health game are postbiotics. Put simply, these are the products that the gut produces as it breaks down dietary fibre. They include short-chain fatty acids (SCFA) such as butyrate. Like good bacteria, postbiotics nourish the gut, giving our mental health another much-needed boost.
To summarise, adding probiotics and prebiotics to our diet helps boost the numbers of good bacteria in our gut, and ensures they’re able to thrive. It’s also important to reduce our intake of high-fat and high-sugar foods at the same time. These can act as fuel for the harmful bacteria, giving it a further advantage.
Plant-based fibre
So, as plant-based fibre fuels the good bacteria in the gut, it’s safe to say that eating more high-fibre foods can go a long way to getting our gut microbiome in good shape. And a healthy microbiome comes with a whole host of benefits.
One of the biggest positives is improved mental well-being And that’s all thanks to the gut-brain axis. A study has shown that the gut actually produces about 90% of our body’s serotonin – a neurotransmitter and hormone associated with happiness. As it feeds the probiotics in our gut, plant-based fibre also has a positive effect on our mental health, by reducing anxiety and depression.
Of course, one of the other key benefits of a diet high in plant-based fibre is improved digestive performance. That’s because it travels to our gut relatively intact, adding bulk to our stool. This, in turn, keeps things moving through our digestive system and makes stools easier to pass, reducing the chance of constipation.
A healthy gut microbiome also contributes to a strong immune system, better sleep and improved cardiovascular health. In fact, the benefits are seemingly endless. So, what can we eat to help give our minds and bodies a boost?
Western vs Mediterranean diets
There’s plenty of evidence to suggest that having a more diverse gut microbiome leads to better physical and mental health. And, if we want to take steps to improve our gut microbiome, the first thing we need to look at is our diet.
Studies have shown that Mediterranean diets are far better for our gut health than western diets. Mediterranean diets are typically more plant-based and are made up of lots of fresh fruit, vegetables, nuts, seeds and oily fish. Western diets, on the other hand, tend to consist of a higher intake of processed, pre-packaged foods, red meat, high-fat dairy products and sugar.
The key difference, however, is that Mediterranean diets are much higher in fibre. It is for this reason that people who follow this type of diet tend to have fewer diseases and better overall health.
The bottom line
There is still work to be done to discover new varieties of plant-based foods that can help boost our gut health. Scientists have some way to go to fully understand the workings of the gut-brain axis, too. However, while more research is needed, it’s looking like gut health will continue to play a big role in the future of nutrition.
The key takeaway so far, however, is that eating more plant-based fibre leads to a nourished and more diverse gut microbiome, and that leads to better overall health. Increasing our intake of diverse plant-based foods doesn’t just benefit our health and well-being - it plays a part in meeting agrobiodiversity and sustainability goals, too. You can read more about it in this article of our blog