In our last article, we discussed how the macro and micronutrients that we consume affect our mood, and more specifically, how they affect our body’s production of neurotransmitters. This time, we will focus on the neuroscience of nutrition and mental health.

What Are Neurotransmitters and Hormones?

Neurotransmitters and hormones are two sides of the same coin. They are powerful molecules that help our body parts communicate with each other. Neurotransmitters help communication within the nervous system, while hormones help regulate other bodily functions, such as heartbeat, digestion, and sleep. The following is quick example to see neurotransmitters and hormones in action: 

Imagine driving at night on a dimly lit road, tired from a long day of work. The radio faintly plays a song in the background as you begin to space out. Abruptly, a deer jumps into the road. You may become startled and suddenly alert. You react fast enough to avoid hitting the deer, and it disappears into the night.

In that moment, your nervous system, quick on the draw, releases neurotransmitters to make your muscles alert and dexterous — controlling the wheel and pressing on the brakes. It also helps you focus by completely tuning out whatever is playing on the radio and temporarily forgetting your exhaustion. Your body is likely releasing norepinephrine, helping you become more alert. 

Immediately afterwards, you may feel your heart pound and muscles tense. Hormones now arrive at your brain, having taken longer to travel through your bloodstream. One such hormone is cortisol from your adrenal glands. Your body adjusts how it uses energy (blood pressure increases and rushes into your limbs so you can react to danger, while blood flows away from your bowels), as an emergency is no time to slowly digest food. 

Once you make sure all danger has passed, your heart rate slowly decreases as the cortisol clears from your bloodstreams. Neurotransmitters and hormones such as serotonin help you relax again. Your body may once again feel fatigued, your brain less alert, preparing for sleep and relaxation to recuperate and regain energy.

As one can imagine, it is healthy to have a balance between excitatory chemicals (the ones that rev you up) and inhibitory chemicals (the ones that calm you down). Many aspects of our lifestyle can affect this balance, but one of the main factors is our diet. 

Adenosine Triphosphate Cycle

You may remember learning about the adenosine triphosphate (ATP) cycle in high school biology class. ATP is our body’s way to generate energy. We can think of ATP like currency: Our brains are greedy and require a lot of the energy that our bodies make. Therefore, researchers have found that when our ATP levels are lower, we are more likely to experience negative mental health symptoms. Part of what fuels the ATP cycle are amino acids. 

Amino Acids

Amino acids create protein in our bodies. They are the foundation of neurotransmitters and can even help repair them. Our gut has the ability to contribute amino acids to our bodies. However, when our gut microbiome is in distress, it cannot supply our body with as many amino acids. This affects our production of energy and neurotransmitters. Part of what contributes to poor gut health is the sugar and caffeine we consume. We also do not help our ATP cycle and amino acid production when we are experiencing stress, getting minimal sunlight, and putting our body through excess or extreme physical activity.  

The Gut Microbiome

Bacteria in our gut are a major player in the production of balanced hormones and neurotransmitters. They help in three major ways:

First, some bacteria help us digest foods that we otherwise would struggle to digest. Dietary fiber and some starches, for example, are broken down by bacteria into helpful components that our body can use. 

Second, in the process of helping us digest, many bacteria produce neurotransmitters and hormones. More than 80% of serotonin is produced in the gut, along with Gama Aminobutyric Acid (GABA) and other hormones that help you relax, regulate your mood, and increase general satisfaction. 

Third, even when not directly producing chemicals, the presence of bacteria stimulates our body to produce neurotransmitters and hormones, such as serotonin and cortisol — which helps regulate our immune system and digestion. In other words, our gut helps our brain, which in turn, helps regulate our gut. 

Balance and Imbalance

When the gut microbiome is disrupted, so too can our neurotransmitters and hormone production be disrupted. This can happen due to a variety of reasons. Chronic stress, for example, strains the ecosystem in our guts and can disrupt the living environment of these bacteria, leading to imbalance in hormone production. Similarly, eating too much refined sugar contributes to gut inflammation, which also can harm the gut microbiome. Some infections can also disrupt our gut microbiome and have been shown to cause irritable bowel syndrome (IBS) in some people.

When these disruptions happen, our neurotransmitter and hormone production become unbalanced, producing too little or much of some. Producing too little serotonin or GABA may lead to difficulty regulating mood, difficulty relaxing, and is often linked with depression and increased aggression. Think of it this way: when we don’t have these inhibitory chemicals to counteract those that rev us up, then we always feel stressed — always feel like there’s a deer on the side of the road trying to jump out at us. 

Another example is dopamine, which curiously can be produced too little or much depending on the specific imbalance. Dopamine helps regulate our satisfaction and reward systems, so not having enough would make it harder to feel satisfaction, excitement, or enjoyment. On the other hand, having too much dopamine is associated with addictive behavior, impulsivity, and even schizophrenia. 

Our melatonin levels are also impacted. When our bodies are imbalanced, we are not absorbing adequate levels of melatonin from our food. This affects our circadian rhythm or our sleep-wake cycle. Sleep is an essential part of mental health and nutrition. Sleep deprivation and oversleeping are some of the primary symptoms we see in depression and anxiety.

Finding Balance

Knowing basic neuroscience of nutrition can help us understand why certain diet choices are healthier, or why some habits make us feel awful. The system of connections between our gut and brain are complicated, with many other potential factors and consequences. 

Among the more serious consequences of chemical imbalances are neurodegenerative diseases such as Parkinson’s and Alzheimer’s. While natural aging contributes to the risk of these diseases, nutritional imbalances can exacerbate the risks. Imbalance in neurotransmitter production is the main effect of both diseases, and this effect can be worsened if the digestive system also contributes to imbalance through improper nutrition and damage to the gut microbiome. 

The central theme in these cases remains the same: Our bodies thrive when we have a balance in the production of neurotransmitters and hormones. Balance allows us to be flexible, feel a wide range of emotions and react appropriately to a wide range of situations. This is why eating healthy is not just about calorie counts or the shape of our bodies; our eating affects how we experience the world.

Kalea Abernathy is a licensed professional counselor (LPC) trained in mental health and nutrition. She values incorporating nutrition into therapy to better support overall wellness through a holistic approach. Her clinical experience has included supporting individuals, couples, and families through multiple therapeutic orientations such as such as dialectical behavior therapy (DBT) and cognitive behavioral theory (CBT).

Peter Yibo Pan is a therapist-in-training currently completing his master’s degree in counseling at Northwestern University, specializing in counseling children and adolescents. Peter practices an integrative, evidence-based approach, combining relational, gestalt, and behavioral elements of traditional therapy. He also utilizes nontraditional interventions such as play therapy and art therapy techniques.