Is it Anxiety? Is it Depression? Or is it … My Gut?

Written By Alexandria Tapsall

You know those “butterflies” you feel in your stomach before a big event? Or that loss of appetite that comes on when you’re anxious? These sensations aren’t just in your head — they’re part of a magical internal communication system called the gut–brain axis (aka. the GBA).

The gut–brain axis is a complex, bidirectional communication network that links your central nervous system (the brain and spinal cord) with your enteric nervous system (the gut).

Essentially, you have a constant feedback loop going on between your digestive system and your brain, and this influences everything from your mood, stress response and cognition to your digestion, metabolism and immune function!

You Have Two Brains!

You heard it. Your gut carries over 100 million neurons, meaning it can actually function semi-independently from your brain.

This ‘brain’ in your gut is regulating your digestion and excretion as we speak and, at the same time as controlling your poop, is also sending messages upwards through nerves, hormones, and chemical ‘messengers’.

The most famous of these messengers is the vagus nerve, responsible for your emotional regulation and your ability to relax. Despite often being described as the ‘highway’ between your brain and body, about 80–90% of this traffic actually travels from the gut to the brain, not the other way around.

This just proves how much influence our digesetive system has over our emotions.

Your Hidden Ecosystem

Now, your gut isn’t just a highway to your brain, it’s also home to trillions of microorganisms — bacteria, fungi, other microbes — collectively known as the gut microbiome. This is a bustling ecosystem that affects your brain chemistry and behavior.

For example:

  • Funny-named species like ‘Lactobacillus’ and ‘Bifidobacterium’ can produce GABA, a calming neurotransmitter that reduces anxiety and promotes relaxation.

  • Others, like butyrate, help synthesize serotonin, dopamine and short-chain fatty acids (SCFAs). These have anti-inflammatory effects and help regulate mood and cognition.

When the microbiome is diverse and balanced, these chemicals keep your gut and brain functioning optimally.

However, when there’s dysbiosis — an imbalance of the good and bad bacteria — inflammation can increase, “leaky gut” can occur and mood-regulating neurotransmitters are thrown off balance.

This is why poor gut health is often linked to anxiety, depression, brain fog, and fatigue.

Stress: Is It All External?

Stress can powerfully influence the gut–brain axis. When stress is chronic, the body’s main stress hormone (cortisol) is released, causing:

  • Slow digestion

  • Altered gut motility

  • Increased intestinal permeability.

  • Reduced microbial diversity -> shift towards inflammatory species.

Similarly, an inflamed or imbalanced gut can send distress signals back to the brain, creating a stress response.

This creates a vicious cycle: Stress harms the gut, harmed gut fuels more stress.

What About Happy?

Around 90–95% of serotonin — your “happy hormone” — is produced in the gut. This serotonin helps regulate mood, sleep, and digestion. Other neurotransmitters such as dopamine (motivation and pleasure), GABA (calming), and acetylcholine (focus and memory) are also influenced by gut activity and microbiota composition.

When the gut is inflamed or imbalanced, the production and signaling of these neurotransmitters can be disrupted, leading to mood changes, poor stress tolerance, and even symptoms of depression or anxiety.

How the Gut–Brain Axis Influences Whole-Body Health

Because this system affects so many processes, an imbalance in the gut–brain axis can manifest far beyond digestion. It can contribute to:

  • Irritable bowel syndrome (IBS) and other functional gut disorders

  • Mood disorders such as anxiety and depression

  • Brain fog and poor concentration

  • Hormonal imbalances through its effects on the HPA (hypothalamic–pituitary–adrenal) axis

  • Skin conditions like acne, eczema, and rosacea (via the gut–skin axis)

  • Weakened immunity, as much of the immune system resides in the gut lining

Nurturing the Gut–Brain Connection

Supporting your gut–brain axis involves lifestyle choices that promote both mental calm and microbial diversity. You can strengthen this connection by:

  • Eating a diverse, plant-rich diet high in fiber and polyphenols

  • Including fermented foods like sauerkraut, kefir, or kombucha

  • Managing stress through mindfulness, breathwork, or meditation

  • Getting adequate sleep to regulate hormones and neurotransmitters

  • Supporting gut healing with herbs (like chamomile, licorice, ashwagandha) and nutrients (like zinc, L-glutamine, magnesium)

  • Practicing vagus nerve stimulation techniques such as cold exposure, deep breathing, humming, or gentle yoga

In Summary

The gut–brain axis reminds us that the mind and body are never separate — they’re in continuous dialogue. Your gut doesn’t just digest your food; it digests your emotions, stress, and experiences too. When this system is nurtured, communication flows smoothly — leading to better digestion, calmer moods, clearer thinking, and overall wellbeing.

Healing the gut is, in many ways, healing the mind. When you care for your belly, your brain thanks you in return.

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Alexandria Tapsall