4 Plant Compounds That Transform the Brain

Source: Austin Perlmutter/DALL-E

There’s no part of our body so tethered to our sense of self as our brains. From our brain wiring and structure come our thoughts, our beliefs, our likes and dislikes, and our actions. Even though we usually feel like the same “self” from day to day, the reality is that our brains are constantly changing as a reflection of our inner and outer environment. While many molecules in our diet alter our brains, certain plants and their compounds can have an incredible and outsized influence on how we think, act, and feel. In this post, we explore four of the most powerful brain-active plant molecules, their natural sources, and their effects on the brain.

1. Caffeine

Caffeine is a naturally occurring stimulant found in various plant species, with coffee beans, tea leaves, and cacao beans being the most common sources. It is also present in kola nuts, yerba mate, and guarana berries. Top natural food sources of caffeine in our diets include beverages like coffee and tea.

How Caffeine Alters the Brain

Caffeine primarily affects the brain by blocking adenosine receptors, which are responsible for promoting feelings of drowsiness and relaxation. By inhibiting adenosine’s action, caffeine increases neuronal firing and the release of neurotransmitters like dopamine and norepinephrine, leading to heightened alertness, improved mood, and enhanced cognitive performance. This can improve concentration and reduce the perception of fatigue, making caffeine a popular choice for boosting mental performance. However, regular consumption can lead to a potential diminishing of caffeine's effects over time and create withdrawal symptoms such as headaches, irritability, and fatigue when intake is reduced or stopped.

2. L-Theanine

L-theanine is an amino acid primarily found in the leaves of tea plants, particularly Camellia sinensis, which is used to produce green, black, and white teas. It is especially abundant in green tea, with some of the highest concentrations found in high-quality matcha tea. Beyond tea, L-theanine is also present in smaller amounts in certain mushrooms, such as the bay bolete (Boletus badius). It is sometimes combined with other compounds, such as caffeine, to enhance cognitive benefits and support focus.

How L-Theanine Alters the Brain

L-theanine exerts its effects on the brain primarily by modulating neurotransmitter levels and promoting alpha-brain wave activity. Dietary L-theanine passes through the blood-brain barrier. Since it’s similar in chemical structure to glutamate, it competes with glutamate for receptors. After binding to receptors, it increases the production of gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter that reduces neural excitability and promotes relaxation. This unique profile helps explain why L-theanine consumption has some data linking it to improved alertness and reduced stress and anxiety, although the generalizability and replicability of these effects are still under review. Additional data supports higher doses of this molecule as influencing alpha brain waves—typically associated with a relaxed yet attentive mental state. At higher levels (for example in supplement form), L-theanine has been linked to jitteriness and headaches.

3. Tryptamines*

Tryptamines are naturally occurring compounds found in various plants and fungi that can affect brain function, often through their interaction with serotonin receptors. Perhaps the best-known plant source is Psychotria viridis (a vine), which contains Dimethyltryptamine (DMT), a powerful psychoactive compound used traditionally in the Amazonian brew ayahuasca. Another notable source is Psilocybe mushrooms, which contain psilocybin, a tryptamine that converts to psilocin in the body, mimicking the structure and function of serotonin. Another source is the yopo tree (Anadenanthera peregrina), which contains bufotenin. These tryptamines are often used in traditional and shamanic practices for their psychoactive and spiritual effects, though they are also gaining attention in modern research for their potential therapeutic applications.

How Tryptamines Alter the Brain

Plant-based tryptamines primarily alter brain function by interacting with the serotonin (5-HT) receptors, especially the 5-HT2A receptor, which plays a crucial role in mood, perception, and cognition. By binding to these receptors, tryptamines like DMT and psilocin induce changes in brain connectivity and neural plasticity, leading to altered states of consciousness characterized by vivid visual and auditory experiences, as well as profound shifts in thought and emotion. These compounds can disrupt the brain's default mode network (DMN), which is associated with self-referential thinking and ego. This disruption may contribute to the therapeutic potential of tryptamines, helping individuals break free from rigid thought patterns and promoting psychological flexibility. Emerging research suggests that these effects can lead to lasting changes in mood and cognition, making plant-based tryptamines a promising area of study for treating conditions like depression, anxiety, and PTSD.

*Due to the high risk of biological and psychological side effects, these molecules need to be approached with caution, and this information does not represent advocacy for their recreational use.

4. Polyphenols

An emerging body of research demonstrates that, while far more subtle in effect, the 8000+ molecules of the polyphenol family found in our foods may have an outsized effect on brain function. Polyphenols are incredibly pervasive and diverse in our diet and have names like resveratrol and quercetin. They give fruits and vegetables their coloration, contribute to flavor, and act as plant defense molecules.

How Polyphenols Alter the Brain

Though they’re often branded as simple antioxidants, polyphenols are now understood to act on diverse pathways within our bodies and brains. Certain polyphenols are believed to modulate epigenetics (our gene expression), while others affect our immune system, including immune cells within the brain. In animal data, quercetin has been shown to target and decrease the expression of pathways related to Alzheimer’s. In addition, curcumin, the major polyphenol found in turmeric, has been found to raise levels of the brain-rewiring compound brain-derived neurotrophic factor (BDNF). Unlike the effects of the other molecules mentioned in this post, the data indicate that most people may experience brain benefits from long-term consumption of polyphenol-rich foods like spices and herbs and colorful fruits and vegetables without much concern for side effects.