Anxiety and depression are serious mental health disorders that affect millions of people globally. Depression is the most common mental health problem worldwide, and in the UK 19.7% of people reported suffering from anxiety or depression. Each year in the US 40 million people are diagnosed with these mood disorders.
There are several factors that can cause these illnesses such as chemical imbalances, inherited risk factors and environmental influences. Another predisposing factor gaining a lot of attention at the moment is that our gut health could be affecting our mental health. Now, this seems kind of crazy right? But there is actually a tonne of research out there that links the behaviours in our gut, with our behaviour and emotions.
The connection between the gut and the brain
The gut and the brain can actually communicate with each other using 3 different methods; the vagus nerve, the enteric nervous system, and the gut-brain axis.
Activity in our brain has a direct effect on our stomach, but what is more surprising is that this relationship is bi-directional. This means that what’s happening in our stomachs can have an effect on our brain.
So knowledge about the link between our gut and our brain isn’t actually that new. From as early as the 1930s scientists have believed that mental health disorders influence gastrointestinal disorders. Early explorations of the gut microbiome showed a close relationship between behavioural issues, mood and bacterial imbalances.
Several other studies also found a close link between gastrointestinal disorders and mental health problems. One study found those who suffered from IBS also commonly suffered from anxiety and depression suggesting a connection between poor gut health and poor mental health.
A further study looking at 1,054 participants identified a specific group of microorganisms that correlated (both positively and negatively) with mental health. Participants with depression had consistently lower levels of two types of bacteria (coprococcus and dialister). A study conducted with 1,063 clinically depressed patients later validated these earlier findings.
How does our gut health affect our mental health?
The gut produces more than 90% of our bodies serotonin. Serotonin is the bodies feel-good chemical that contributes to feelings of wellbeing and happiness. As well as producing serotonin, our gut microbiome also produces norepinephrine. This neurotransmitter is involved in maintaining focus and the production of GABA (the neurotransmitter that makes you feel calm.) The neurotransmitters created in your gut travel along nerves to the brain where they affect mood and behaviour. This strongly suggests that a healthy gut equals a healthy, calm and happy mind.
Along with producing neurotransmitters, our gut microbiome also produces strong antioxidants. These antioxidants travel to the brain and can reduce inflammation. But how does inflammation relate to depression? Well, brain inflammation contributes to certain mental illnesses, such as depression and anxiety. In fact, brain inflammation was 30% higher in people diagnosed with clinical depression, and as the inflammation became more severe, so did their depressive symptoms. If our gut microbiome is disrupted then the production of these antioxidants reduces. This then leads to an increase in brain inflammation which, could, in turn, lead to more severe symptoms of anxiety and depression.
Which foods help our gut microbiome thrive?
Having an unbalanced gut microbiome is becoming an increasing problem in today’s society. With more people eating processed, sugary foods, and meats pumped full of antibiotics it is not surprising that the bacteria living in our guts isn’t doing so well.
The best way to create a healthy gut microbiome is through your diet. Luckily, the lifespan of these bacteria is around 20 minutes, which means you have the opportunity to improve your gut health with every single meal you eat. This also means you can transform the health of your gut rapidly. The most effective way to improve your gut health is to eat a range of whole, organic plant-based foods like fruits, vegetables, legumes, beans and whole grains. The following foods are extremely important for improving your gut microbiome.
In a study conducted in 2018, walnuts were found to improve gut health by increasing the number of microbes that produce butyrate, a beneficial metabolite for colonic health. Other nuts can also be beneficial for gut bacteria, but walnuts were found to be the best.
Probiotics are either naturally occurring or added artificially. You may be familiar with yoghurts that have “live cultures” added to them. These live cultures are the good bacteria we want more of.
The best probiotic foods to eat are fermented foods such as tempeh or kimchi. Fermented foods naturally grow healthy strains of bacteria. When digested these strains help the bacteria in the gut function properly.
A study reported that fermented foods were the most beneficial way to get probiotics. Fermented foods are naturally acidic so the probiotics are better able to survive your stomach acid and make it to your gut.
Fibre is essential for a healthy microbiome. Things like legumes, beans, peas, oats, bananas, berries, asparagus and leeks have all been shown to positively improve gut health. In fact, eating enough fibre is key to helping the healthy bacteria in your gut to thrive.
Leafy greens include things like spinach, kale, and collard greens. A 2016 study found that leafy greens contain a substance called sugar sulfoquinovose, which boosts your gut bacteria. This is because the bacteria use these sugars as a food source in order to grow.
In a 2017 Penn State study cruciferous vegetables, like broccoli and Brussels sprouts, were found to provide the ingredients for a chemical vital for gut health. This chemical protects the barriers in our stomach and other important digestive organs and stops toxins from entering.
So what are you waiting for? Start adding these foods to your meals to improve your gut microbiome and your mood.