There is a conversation going on inside you right now that you don’t hear – a constant biochemical conversation between two of your organs that you likely didn’t think of as connected to one another at all.
Your gut and your brain are talking to one another. They’ve been doing it since before you were born, and what they say to one another (the signals they send along a biochemical highway researchers call the gut-brain axis) has a direct and lasting impact on your cognition, your mood, and your brain’s ability to sustain its own immune system for the long run.
You were never taught this in school. Most of us think of digestion and immune health as separate things, but we now know they aren’t. And what they are, quite importantly for our long-term health, is deeply, intricately connected.
What is the Microbiome, Anyway?
The microbiome is the collective term for the bacteria, fungi, viruses, and other microscopic life growing in and on your body (but mostly your digestive tract). There’s more of these things living inside you right now than you ever knew existed – trillions of them.
For a long time the things that live inside you were mostly considered to only help you with digestion. That’s a fair assessment, since they do break down food, absorb nutrients, and process waste, but a healthy microbiome does a lot more than that.
A healthy, diverse microbiome produces neurotransmitters (which is where a lot of your serotonin comes from), vitamins, regulates immune responses, keeps your gut lining intact, and sends signals up to your brain via your vagus nerve.
A disrupted microbiome sends proinflammatory signals up to your brain, contributing to neuroinflammation: an unhealthy immune response within the brain that is associated with neurodegenerative diseases.
Gut-Brain Axis: Two-Way Street, Mostly
The gut-brain axis refers to the connection between your gut and your brain, and the ways in which the two of them influence and are influenced by one another.
The vagus nerve is the main highway that runs between the two of them, sending signals in both directions. Most of those signals, researchers have found, originate in your gut – and not the other way around.
When your gut is unhealthy, it sends mostly proinflammatory signals to your brain. When it’s healthy, it sends mostly anti-inflammatory signals. This, in turn, affects the microglia, the immune cells of your brain, and the microglia’s ability to sustain and protect neurons.
What Disrupts the Microbiome?
There are a lot of unfortunate things that can disrupt your microbiome, most of which are things you’re already aware of.
Ultra-processed foods and diets high in sugars disrupt gut health by reducing the diversity of your microbiome. Chronic stress also takes a toll on it, due to the stress response cascade and the release of cortisol, which follows the same pathways as stress hormones in your gut.
Antibiotics are a necessary evil in some cases, but they can also reduce diversity in your microbiome every time you take them.
Alcohol, toxins, lack of sleep, or even feeling lonely can all negatively impact your microbiome and by extension your brain.
But here’s an interesting thought – the things that negatively impact your microbiome are often the same things that negatively impact your cognition. This isn’t a coincidence – it’s an explanation as to why taking care of your microbiome can have such a profound effect on your cognitive function.
What Improves the Microbiome (And Your Brain’s Immune System)?
Unfortunately, as mentioned before, a lot of the things that negatively impact the microbiome are surprisingly common in our daily lives. And that’s not all bad news – because as it turns out, the things that do improve it aren’t that hard to implement, either.
Diet high in fiber and fermented foods supports beneficial bacteria and their ability to send anti-inflammatory signals to your brain. A diet rich in variety stimulates the growth of diverse microbiota, and the anti-inflammatory effects of a healthy diet are also seen in improved cognitive function.
Getting regular sleep, managing stress, exercising, and cutting out ultra-processed foods all improve both gut and brain health.
Small steps in the right direction help both of these incredibly important systems, and the more steps you take, the better your cognition will be for the long run.
A New Way to Think About Your Food
Every meal is a message to your gut — and through your gut, to your brain. Not a verdict. Not a test you can pass or fail. A message. And like any ongoing conversation, what matters most is not any single exchange but the overall tone and pattern over time.
When we think about food this way — not as fuel for the body in some mechanical sense, but as communication with the microbiome that shapes our cognitive health — the choices we make take on a different quality. They become less about restriction and more about relationship. Less about discipline and more about care.
Your gut and your brain are talking. You get to help shape what they say to each other.
Leave a Reply