The three brains

You may have heard that the gut is called the second brain — this is due to the large network of neurons it contains, which connects with our “first brain,” forming the gut-brain axis. This axis works bidirectionally, meaning that not only do signals from the brain influence intestinal activity (mainly motility-related signals), but signals from the gut also influence brain function, affecting our decisions, mood, and emotions.

As if having two brains weren’t enough, a growing body of research now suggests that we have yet another brain — the gut microbiota. This is truly fascinating!

The gut microbiota: more than just “little bugs”

The gut microbiota is not just a collection of microorganisms (“little bugs”) living in our intestines. It’s a complex microbial system made up of bacteria, fungi, yeasts, intestinal parasites, viruses, and others that coexist harmoniously in symbiosis within our body. The human microbiota represents between 1% and 3% of total body mass and can weigh up to about 1.4 kg (Greenlaw and Ruggiero, 2015). Did you know that for every human cell, there are ten microbial cells?

When we realize that we are more microbial than human, and that these microorganisms can “communicate” with the central nervous system — thereby influencing brain function and regulating human behavior (Cryan and Dinan, 2012) — the idea of the microbiota as our “third brain” begins to make perfect sense.

The most well-known function of the microbiota is its role in digestion and inflammation. However, recent research links it to obesity, allergies and food sensitivities, chronic diseases, mood regulation, and immune system function.

Multiple studies are now exploring how gut microflora influences other cognitive functions, challenging the old paradigm that the “brain” alone is responsible for cognition. Magnusson et al. (2013) note that “bacteria can release compounds that act as neurotransmitters, stimulate sensory nerves and the immune system, and affect a wide range of biological functions.”

Among these neurotransmitters, serotonin — produced by the gut microflora — plays a key role in maintaining mood balance, and its imbalance contributes to depression. A study published in Cell in April 2015 found that certain gut bacteria influence serotonin production by affecting tryptophan concentration, an essential amino acid required for serotonin biosynthesis (Yano et al., 2015). It was once believed that serotonin was produced only in the brain, but most peripheral serotonin is actually produced in the gut — up to 90%, according to recent studies.

Therefore, the microbiota–gut–brain axis refers to a bidirectional communication network between the central nervous system, the gastrointestinal tract, and the gut microbiota. Serotonin acts as a key neurotransmitter at both ends of this network.

What you eat affects all three of your brains!

Diet is the most important factor influencing the composition of gut microflora. The way you eat determines how your microbiota is nourished.

The 3R Protocol is an innovative strategy. It removes foods that cause sensitivities, as well as refined carbohydrates, added sugars, and processed fats. It replenishes the body with foods rich in healthy fats, probiotics, high-quality proteins, and plenty of vegetables — all of which promote the renewal and balance of gut microbiota composition.

This strategy is part of managing chronic inflammatory diseases such as obesity, stress-related disorders, neurodevelopmental disorders like autism, and autoimmune conditions.

That’s why, to achieve optimal mental health, better cognitive function, memory, behavior, and mood, we must not only take care of our first brain but also evaluate the health of our second brain (the gut) and our third brain (the gut microbiota), ensuring they are all functioning properly.

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References:

Beilharz, J., Kaakoush, N., Maniam, J., & Morris, M. (2017). Cafeteria diet and probiotic therapy: cross talk among memory, neuroplasticity, serotonin receptors and gut microbiota in the rat. Molecular Psychiatry.

Cryan, J., & Dinan, T. (2012). Mind-altering microorganisms: the impact of the gut microbiota on brain and behavior. Nature Reviews Neuroscience, 701-12.

Greenlaw, R., & Ruggiero, M. (2015). Your third brain: the revolucionary new discovery to achieve optimum health. Centennial, CO: Extraordinary wellness Publishing.

Magnusson, K., Hauck, L., Jeffrey, B., Elias, V., Humphrey, A., Nath, R., . . . Bermudez, L. (2013). Relationships between diet-related changes in the gut microbiome and cognitive flexibility. Neuroscience. , 128-40.

otros, Y. y. (2015). Indigenous Bacteria from the Gut Microbiota Regulate Host Serotonin Biosynthesis. Cell., 161(2), 264–76.

Proctor, C., Thiennimitr, P., & Chattipakorn, N. (2017). Diet, gut microbiota and cognition. . Metab Brain Dis.