The Chemistry of Well-Being
by Marcus Rodrigues
The Gut–Brain Axis: The Highway of Emotions
Have you ever felt “butterflies in your stomach” when anxious or lost your appetite after a scare? That’s because the gut is not just a digestive organ—it has its own nervous system, the Enteric Nervous System, with around 500 million neurons.
In practice, it’s as if there’s a “second brain” inside your body, constantly communicating with the main brain. And this isn’t just theory: about 90% to 95% of serotonin, the neurotransmitter linked to well-being, is produced in the gut. When this environment is inflamed or imbalanced, the production of this “happiness chemistry” is affected as well.
It’s no coincidence that the WHO recommends consuming at least 400g of fruits and vegetables per day, precisely because of their role in disease prevention and overall balance.
The “Cranky Gut” Myth
The connection between the gut and mood is so real that it even shows up in everyday language. The idea of being “full of it” or irritable has roots in the literal notion of being backed up.
When intestinal transit is slow (constipation), there’s increased reabsorption of toxins and a rise in inflammatory compounds that impact the central nervous system. This can lead to irritability, stress, and mood changes—not just psychological, but biochemical.
This is where the gut microbiota comes in: the community of bacteria living in your intestines that directly influences this balance.
Microbiota in Practice: What to Eat (and What to Avoid)
To keep this system working well, you need to feed the right bacteria.
Prebiotics (found in oats, garlic, green banana biomass, strawberries, blackberries, guava, and apples with skin) act as food for beneficial bacteria. Probiotics (natural yogurt, kefir, kombucha, sauerkraut, and kimchi) are the live microorganisms that help balance this ecosystem.
But here’s an important detail: not every fermented food is probiotic. Processes like pasteurization kill bacteria—both good and bad—so they need to be alive at the moment of consumption.
In practice, the most effective approach is combining both. A simple example is the “dynamic duo”: oats and strawberries with natural yogurt at breakfast.
Another key factor is variety. The more colors on your plate, the greater the diversity of fibers—and the more types of beneficial bacteria you nourish.
Some nutrients also directly support mental health:
Tryptophan (avocado, seeds, eggs) plays a role in serotonin production;
Magnesium (leafy greens, dark chocolate) helps regulate stress;
Omega-3 (fish, flaxseed, chia) reduces inflammation and supports brain health.
On the other hand, diets high in ultra-processed foods do the opposite: they feed harmful bacteria, increase intestinal permeability (leaky gut), and promote inflammatory processes that can affect mood.
The Key Point: Diversity Is What Changes the Game
In the end, it’s not about a single food—it’s about the whole picture.
Your gut doesn’t need a “superfood,” but diversity. The more varied the fruits you eat, the more complete the support for your microbiota.
📍 The Happiness Hack: by using Fruit Map to find fresh fruit in your neighborhood, you’re not just saving money or eating better—you’re consuming more intact fibers and freshly harvested phytochemicals.
A practical way to apply this is the color rule: if you’ve already eaten something red today (like strawberries), aim for fruits of other colors, such as purple (blackberries, jabuticaba) or orange (mango, cashew). This helps nourish different bacterial colonies and supports serotonin production.
References:
JACKA, Felice N. et al. A randomised controlled trial of dietary improvement for adults with major depression (the “SMILES” trial). BMC Medicine, 2017;
CARVALHO, J. L.; LIMA, S. C. S. The influence of gut microbiota on mental health: an integrative review. Revista de Nutrição e Saúde Mental, 2022;
LIANG, S. et al. Recognizing the role of the gut microbiota–gut–brain axis in psychiatric disorders. Pharmacological Research, 2018;
BRASIL. Ministry of Health. Dietary Guidelines for the Brazilian Population. 2nd ed., 2014.
