The Link Between Gut Health & Mental Health
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The Link Between Gut Health & Mental Health

Deep within the 25 feet of your intestines, your microbiome is working to defend you against pathogens and absorb the vitamins and amino acids that you consume.

‍The gut is our largest sensory organ, with a surface area 40 times that of our skin. One of its central functions is to gather information for the brain, communicating that we’re getting enough nutrients, how our immune cells are functioning, and what our hormones are up to.

Deep within the 25 feet of your intestines, your microbiome is working to defend you against pathogens and absorb the vitamins and amino acids that you consume. Immune cells learn to mobilize in the gut, and it’s home to more than 20 varieties of hormones.

The gut is our largest sensory organ, with a surface area 40 times that of our skin. One of its central functions is to gather information for the brain, communicating that we’re getting enough nutrients, how our immune cells are functioning, and what our hormones are up to.

The importance of maintaining the health of this exquisitely sophisticated organ and its resident microbiome is clear. But what exactly do we mean by a “healthy” gut? A healthy gut contains a diverse population of microbes, creating a balance of beneficial and “bad” bacteria. The presence of some “bad” bacteria helps the immune system recognize which microbes to fight.

In an unbalanced microbiome, “bad” bacteria — the pathogenic kind that can cause infections or give us food poisoning — flourish. This triggers a response from the immune system, and results in increased inflammation which has been linked to depression. Although the exact nature of the relationship between inflammation and depression isn’t yet fully understood, studies suggest that a balanced microbiome may help create the conditions for a healthy symbiotic relationship between our gut and our mind.

There’s an on-going, complex “conversation” occurring between the gut and the brain, and it’s mediated by the vagus nerve — actually a collection of nerves, the longest in the body. The vagus nerve is responsible for the “rest and digest” component of the autonomic nervous system, and it passes information back and forth between the brain and the gut, regulating heart rate, respiratory function, and digestion, as well as reflexes we don’t need to think about to perform, like swallowing and sneezing. How well it facilitates the gut-brain conversation can impact our health in multiple ways, and an underactive vagus nerve may struggle to regulate the body’s stress response, contributing to increased anxiety and depression. Preliminary research suggests that the diversity of the microbiome can enhance the functioning of the vagus nerve. 

What does this have to do with kombucha? We’re not sure yet. It’s certainly not as simple as saying that drinking kombucha will make you happy - other than, of course, by way of its deliciousness. But studies show that symptoms of a high stress level may correlate with an absence of particular strains of gut bacteria in the microbiome. It doesn’t necessarily follow that replacing those strains of bacteria will improve stress-related symptoms - we’re talking about potential correlation here, not causation. But the data that’s slowly emerging does suggest that certain elements of nutrition, including beneficial bacteria, may affect vagus nerve activity via the microbiome, impacting communication with the brain and helping with stress regulation.

The gut is an ecosystem whose complexity continues to emerge. Having a healthy gut means having enough good bacteria, along with a scattering of “bad.” In other words, rather than trying to eliminate the bad, the way to achieve gut health is to faithfully tend the good. So what can we do to nourish our hard-working gut? Probiotic-rich foods like raw kombucha, kefir, yogurt, and sauerkraut feed the beneficial bacteria in the microbiome and help maintain its balance. Accepting the bad with the good doesn't just help sustain us during difficult times. It also helps us keep our guts healthy!