Today’s lesson is all about the fascinating gut-brain axis. For those not acquainted, this is the connection that runs between our gut and our brain, and it’s a very strong connection at that.
To speak a little more technically, it is the “communication between the central and the enteric nervous system, linking emotional and cognitive centres of the brain with peripheral intestinal functions.” Essentially, studies have shown that the happier the gut, the happier the brain and that gut microbiota can influence neuro-endocrine systems associated with stress, anxiety and memory function.
It’s so focal on the agenda, in fact, that funding has been put forward to explore how the gut microbiome may be key in diagnosing and treating Alzheimer’s disease specifically.
“The gut is often referred to as our ‘second brain’ as it can control our emotions, stress response and cognition,” stated Dr Pradeep Manuneedhi Cholan, Macquarie University post-doctoral fellow.
“Previous research has shown that the metabolites produced by bacterial species in the gut can impact inflammation in the brain, which can either exacerbate or alleviate the progression of Alzheimer’s disease,” Dr Cholan said.
How does the gut-brain axis work?
The gut-brain axis consists of both physical and chemical connections between your gut and your brain.
- The chemical connection involves the neurotransmitters and other chemicals produced in your gut by your microbiome (these influence your mood and mental function) and can have an impact on the HPA-AXIS.
- The physical connection involves the vagus nerve (the main component of our parasympathetic nervous system) which runs from the base of our brain stem into our digestive system.
“You know when you get bad news and get that sinking feeling in your stomach or you are nervous and feel “butterflies in your stomach”? Or diarrhoea/constipation when stressed, or nausea when you’re nervous? This is the vagus nerve sending signals from the brain to the digestive system,” said Michaela Sparrow, naturopath and nutritionist of The Longevity Remedy.
“We also have neurons in both our brain and our gut (100 billion in the brain and 500 million in the gut). Neurons, or nerve cells, tell our body how to behave. So when the gut function is imbalanced (through microbiome dysbiosis, intestinal permeability or more) the neurons in the gut will impact the neurons in the brain, the vagus nerve will send altered signals and neurotransmitter deficiencies can occur.”
So that’s why supporting healthy microbiome function and gut wall health is essential when treating any type of mood disorder. As we said, happy gut, happy brain and emotions.
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Genetics and the gut-brain connection
Sparrow also pointed out that genetics do play a role in whether people have a healthier or stronger gut-brain connection.
“There are genes that will impact neurotransmitter production, gut barrier integrity, inflammation and immune response. One of the main gene variants is MTHFR, which plays a role in neurotransmitter production. 44 per cent of women have a variant on their MTHFR gene that impacts its ability to convert folate into its active form, elevates homocysteine and disrupts the immune response. These can severely impact a person’s mood and healthy gut-brain connection (among many other things).”
Other influences on the strength of a person’s gut-brain connection include early life trauma and illness.
The gut-brain axis and anxiety
Sparrow points out that there are a few ways that the gut-brain axis can contribute to anxiety:
- Microbiome and neurotransmitter production: The bacteria in the gut both produce and influence the levels of neurotransmitters such as serotonin (happy hormone), gamma-aminobutyric acid GABA (inhibitory/calming hormone) and dopamine (motivation hormone) all of which are critical in the regulation of mood. If the microbiome is unhealthy and imbalanced this will impact the levels of these neurotransmitters in the body and play a significant role in mood disorders such as anxiety (in particular GABA).
- Microbiome, gut wall and immunity: Poor gut wall health can influence the immune system due to its role in increased inflammatory responses which is linked to anxiety and other mood disorders and creates inflammation in the brain..
- HPA-Axis: The HPA-Axis regulates the stress response and influences the nervous system. Increased intestinal permeability and microbiome dysbiosis both puts stress on the HPA-Axis, activating the sympathetic nervous system (fight or flight response) leading to anxiety.
What can negatively affect my gut-brain connection?
- Chronic stress & high cortisol
- Antibiotics
- Trauma
- Grief
- Nutritional deficiencies: magnesium, zinc, b vitamins, vitamin d
- Regular alcohol intake
- Not enough physical exercise (even walking makes a difference!)
- Genetics
- Early environmental exposure to diverse microbes
What can I eat to support my gut and brain?
- Anti-inflammatory foods to bring down inflammation in both the gut and brain. These include berries, any red/orange/purple fruit and vegetables and oily fish.
- Zinc and magnesium-rich foods to support gut wall health and neurotransmitter production. This includes chia seeds, hemp seeds, pepitas, chicken, green leafy vegetables, red meat, oysters, legumes and bone broth.
- B Vitamin Rich Foods (B1,B2,B3,B5,B6,B9,B12) for gut wall health, neurotransmitter production, methylation and brain health. For example, red meat, chicken, eggs, salmon and dairy.
- Prebiotic foods (foods for the microbiome), including olive oil, green tea, fennel, asparagus, onion, garlic and globe artichokes.
- Fermented foods (rich in beneficial bacteria), such as kimchi, sauerkraut, kefir, kvass, pickles and apple cider vinegar.
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