Do you trust your gut? Emerging science showing a clear connection between gut health and mood suggests you probably should.
Over the last half-decade, research has been piling up around the ‘gut-brain axis’ — the system of biochemical signalling that takes place between your gastrointestinal tract and your central nervous system — with serious implications for the health of both.
Crucially, the signals go both ways: meaning that stomach troubles can lead to struggles with mood, while stress or worry can cause a nasty gut reaction.
Some research teams are already trying to identify specific microbes and their effects, while others think that gut health might be one key to combating conditions like, depression, anxiety, or even Alzheimer’s and Parkinson’s disease.
But with the science where it is right now, can you control the connection for the good of your physical and mental health? And if so, where do you start?
How is gut health connected to mood?
Firstly, it helps to understand a bit of biology starting with neurons; the cells found in your brain and central nervous system that tell your body how to behave.
There are roughly 100 billion neurons in the human brain but about five times that number in your gut, mostly connected by the vagus nerve and chemicals called neurotransmitters.
Your gut is also home to a huge community of microorganisms, including bacteria, viruses and fungi - but the exact makeup of these communities varies hugely depending on what you eat, what you do, and even where you live.
A recent study, for instance, found that people experiencing depression, anxiety, bipolar disorder and psychosis were consistently found to have lower levels of two types of bacteria (faecalibacterium and coprococcus, if you’re taking notes) that have an anti-inflammatory effect within the gut than a control group, with further analysis showing high levels of bacteria with pro-inflammatory effects.
But there’s also a physical dimension to the relationship. Professional athletes, for example, have radically different gut fauna from more couch-prone types — often boasting high levels of the bacteria found in ‘naturally’ skinny people. And there’s a growing body of research suggesting that this isn’t just correlation, or a one-way relationship: altering your gut microbiome genuinely seems to impact mood, as well as various mental health conditions.
A 2017 study published in the journal Microbiome found that, in mice at least, gut microbes seem to influence brain molecules called microRNAs, which can impact how genes are expressed in the body - including increasing the incidence of stress and anxiety-related disorders when they misfire.
Meanwhile, a recent review of 21 studies on the subject found that 11 showed that regulating intestinal bacteria could have a positive effect on anxiety symptoms - not the most conclusive odds, but probably enough to be worth a try.
How to improve your gut health and mood?
So, with all this in mind, how do you start to fix your gut-brain connection? It’s important to appreciate that there’s currently no consensus on exactly which organisms affect different aspects of your mental state - so you can’t self-prescribe a diet that’ll specifically target stress or anxiety.
Instead, you should aim to improve the overall diversity and health of your gut bacteria, by adding both prebiotics and probiotics to your diet - the former is fibre that your gut bacteria can eat, while the latter are live bacteria.
Prebiotics are easy to add, by adding more legumes, beans, and peas, oats, bananas, berries, garlic or onions to your regular rotation. Probiotics are a bit more tricky - you’ll need to expand your menu to include kimchi (works great in toasted sandwiches), kefir (nice as a post-gym snack), sauerkraut (eat it in wraps or with eggs) or certain types of cheese (think aged cheddar, gouda or gruyere). An even easier way to ensure you're feeding your gut plenty of probiotics is to take a supplement such as U ULTRA Immunity. It contains chicory inulin, a powerful prebiotic that's clinically-proven to play a role in reducing inflammation, fighting harmful bacteria, and improving mineral absorption.
It’s also important, though, to eat other foods that encourage better gut health - including omega-3 fatty acids, found in oily fish, that studies show correlate with better microbiome diversity, or polyphenol-rich foods like green tea and olive oil that encourage healthy bacteria and might improve cognition.
And finally, you should cut down on processed foods, which some studies indicate can worsen depression: replace it with the above, at least where you can.
If you’re struggling with mental health your first step should be to consult a professional. If you’ve already got support in place, though - or you’re just looking to see if you can improve your mood by changing your menu - the best strategy is to make a couple of tweaks at a time and see what works before you make more dramatic changes.
One day, it’s likely that doctors will genuinely be able to prescribe bacteria that’ll help your brain: until then, do what you can to be kind to yourself. And to your gut.