Foods that improve your mental and brain health

Dr. William Lee, physician-scientist and New York Times bestselling author of "Eat to Beat Disease," joins Dr. Mark Hyman to explore a new frontier in nutrition: how food compounds directly influence the brain, mood, and mental health through the gut microbiome.

The brain and gut are connected

The relationship between the gut and the brain is not metaphorical. The vagus nerve, the tenth cranial nerve, connects the brain to the gut through thick nerve cables. More than 80-90% of the signals travel upward, from the gut to the brain, not the other way around. The gut microbiome, with its 39 trillion bacteria living primarily in the cecum, can send direct messages to the brain and alter mood, anxiety, and behavior.

Dr. Hyman describes a revealing case: a 9-year-old girl with extremely aggressive behavior who was repeatedly expelled from school. A microbiome analysis revealed a massive overgrowth of pathogenic bacteria and fungi. With an antibiotic and antifungal, her behavior normalized within days. It wasn't a psychological problem: it was the gut sending toxic signals to the brain.

The flavorome and the dark matter of nutrition

Dr. Lee introduces the concept of the "flavorome": the set of molecules that give food its flavor and that, when ingested, interact with gut receptors, the microbiome, and through the vagus nerve, the brain. An article in the New England Journal of Medicine catalogued 139,000 distinct compounds in foods that regulate human biology, most still unstudied.

We've thought about nutrition in terms of proteins, fats, carbohydrates, vitamins, and minerals, but that framework leaves out millions of active phytochemicals that interact with our receptors, metabolism, microbiome, and brain chemistry in ways we're only beginning to understand.

Polyphenols as brain medicine

Polyphenols are the natural chemicals that give plants their color and flavor. Plants produce them to defend themselves against disease and parasites: they are their immune and repair system. When we eat them, we co-opt that defense system for our own benefit.

Strawberries, for example, contain ellagic acid. This compound directly reduces inflammation and, by feeding beneficial gut bacteria, stimulates the production of short-chain fatty acids that also calm inflammation. Clinical studies show that one cup of strawberries per day over several weeks reduces depression, improves cognition, and especially improves memory. Organic strawberries have higher polyphenol concentrations because they must defend themselves against natural pathogens, following the principle of hormesis.

With fruits you don't peel, like strawberries and apples, choosing organic matters: pesticides penetrate up to 20% into the skin and are not removed by washing.

Specific compounds with mood effects

Some specific compounds from the plant kingdom have direct effects on mental wellbeing:

• Mentoflavone (cantaloupe): A compound found in ripe cantaloupe with demonstrated anxiolytic effects. The characteristic aroma of ripe cantaloupe comes from this compound.
• Anandamide (dark cacao, truffles): Stimulates the endocannabinoid system in the brain, the same system THC from cannabis activates, producing relaxation and wellbeing. The mood lift people experience from dark chocolate has a real molecular basis.
• Lion's mane mushroom: Stimulates brain connectivity and repair. Used with promising results in traumatic brain injury cases.

Inflammation as the common denominator

From schizophrenia to bipolar disorder, major depression, and autism, a common thread emerges in research: brain inflammation. Polyphenol-rich foods are anti-inflammatory. Ultraprocessed foods, rich in sugar, starch, and additives, are pro-inflammatory. A dietary choice is, literally, a decision about your brain chemistry.

Dr. Hyman's concrete reset protocol: 10 days eliminating gluten, conventional dairy, sugar, starch, alcohol, caffeine, and ultraprocessed foods, replacing them with vegetables, fruit, quality protein, nuts, and healthy fats. Across thousands of participants, the result was a 70% reduction in symptoms from all conditions in 10 days.

Neurogenesis and brain regeneration

The brain can regenerate. Foods that stimulate angiogenesis (new blood vessel formation) also support neuronal growth, because new nerves need vessels to nourish them. Dark chocolate and barley with beta-glucan are examples of foods that stimulate this process. Medicinal mushrooms like reishi, turkey tail, and lion's mane also activate genes for brain repair and connectivity.

Conclusion

The gut microbiome is not a trend: it's the intermediary between what we eat and how we feel, think, and behave. Polyphenols from fruits, vegetables, and phytochemically rich foods are the most accessible lever for reducing brain inflammation, improving mood, and supporting mental health. Diet doesn't replace psychiatric treatment when it's needed, but it's a powerful and underappreciated starting point for anyone looking to improve cognitive function and emotional wellbeing.