The link between our gut and our brain
We learn it from a very early age; what happens in our brain has an effect on our gut. We all get butterflies when we are anxious, even to the point of having an upset stomach and feeling sick. Our gastrointestinal tract responds to emotion. Our gut has been named the ‘second brain’ by scientists, and as Emeran Mayer, professor of physiology, psychiatry and biobehavioral sciences at U.C.L.A says: “A big part of our emotions are probably influenced by the nerves in our gut”.
It goes the other way, as well – problems in our stomach could indicate problems in our brains. There are 500 million neurons in our gut, which are connected to the 100 billion neurons in our brain via neurotransmitters in the nervous system, and signals go both ways. Amazingly, around 90% of the information goes from stomachs to our brains, rather than the other way around. This communication line is called the gut-brain axis, and understanding it can help us understand how what we eat can impact our brains.
The Gut-Brain Axis
So what makes the gut-brain axis work? It all comes down to our gut microbiome. This is a collection of trillions of microorganisms (mainly bacteria, but also fungi, viruses and archaea) that live in our digestive tract. These little guys can produce neurotransmitters (such as serotonin and dopamine) that then send messages to our brains, and play a crucial role in our mood and brain function.
Not only that, but they play a critical role in producing short-chain fatty acids, which are anti-inflammatory. This helps protect our brains against neurodegenerative diseases as well as helping us think more clearly.
Did you know that “the gut provides approximately 95% of total body serotonin”? Also known as a ‘happy hormone’, serotonin has a huge impact on our mood, sleep and optimism. If we don’t look after our guts, it will have a direct impact on our mental well-being.
Why do we need a healthy Gut-Brain Axis?
We are only just really learning about the importance of a healthy gut-brain axis. A 2021 study looked at the role that the gut-brain axis has on our cognitive performance, as well as links to psychiatric disorders. While it acknowledged that more research was required, it concluded that ““A healthy gut for a healthy brain” represents not only a slogan, but an increasingly consolidated concept…”
If we have a more diverse gut microbiome, we will have better cognitive function, as well as feel better. As Dr Kirsten Berding put it following a study she worked on in 2021 “the preliminary results suggest that it really does help your mood and mental health to eat a diet that is microbiota friendly.”
How do we keep a healthy Gut-Brain Axis?
The good news is that it is quite easy to keep a healthy gut-brain axis – we just need to eat well. There are certain foods that we can focus on :
- Fermented foods: Yoghurt, sauerkraut and some cheeses – these contain live bacteria that help the gut microbiome. Surprisingly, a good dollop of yoghurt is also one of the few dietary sources of iodine (other than seafood), a mineral essential to the regulation of metabolism. It’s also an excellent source of CLA, a ‘good’ fat that actually promotes weight loss around the belly. Even more interestingly, if you combine yogurt with banana, the inulin (probiotic fibre) will fuel the growth of the healthy bacteria in the yogurt and help regulate digestion, and boost immunity.
- Omega-3 fats: Salmon, tuna (oily fish) – omega-3s also play a part in increasing levels of good bacteria. We’ve all heard that fish is brain food, but it also improves poor mood. When studies compare the mood disorders in different countries, populations that eat the most ifsh have the lowest rates of depression, bipolar disorder, postpartum depression and SAD. Patients diagnosed with depression tend to have lower levels of omega-3s in their blood and 20-30% less DHA in their brain. A study in 2008 even found fish oil to have equal efficacy to Prozac in the treatment of depression!
- High-fibre foods: Fruit, vegetables, seeds, nuts – fibre helps to feed these good bacteria. Fibre can be thought of as the ‘conductor’ of the complex orchestra that is your digestive system. Extracting all the nutrients your brain needs takes a healthy gut, and this is where fibre comes in. Diets low in fibre have been linked to depression and increased risk of suicide. One reason is that fibre is an indicator you’re are eating foods like whole grains and plants that contain all the essential elements of brain health. Another is that fibre reduces overall inflammation, helps avoid spikes in blood sugar and insulin, which over time cause a deterioration of the blood-brain barrier that keeps toxins out of the brain, so they can’t disrupt mood regulation, memory and brain growth. By making sure that we include the whole fruit in our smoothies, you improve your intake of fibre – much better for you than pure juice!
- Prebiotic foods: Bananas, garlic, onions, asparagus – these contain complex carbohydrates that our bodies can’t digest, but the good bacteria can and they love it. Garlic, as part of the allium family, also contains the trace mineral chromium, which is needed for a proper response to insulin. But more than that, it influences the uptake of tryptophan which is a precursor to serotonin – the good mood neurotransmitter.
Hopefully this is evidence enough (if you needed it), that what we eat really is at the core of how we feel. Starting the day with a smoothie (we like Avo-Go-Go) will get you off to a good start, and starting the day strong, as we know, makes it more likely to continue with healthy habits. Take a look at our Immunity Bundle range – plenty of options that include delicious fruits and vegetables to get your gut-brain access firing on all cylinders.