Protein and Anxiety: How Amino Acids Influence Neurotransmitters

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When we think of protein, we usually think of muscles and strength. But protein also plays a foundational role in how your nervous system functions, including your ability to handle stress.

Protein supplies your body with amino acids, and amino acids are involved in nearly every process that keeps you going. Of particular interest when it comes to anxiety is the role amino acids play in neurotransmitter activity, the chemical messengers that influence how up or down you feel.

Understanding this connection helps explain why food choices can influence mood, stress tolerance, and emotional regulation in ways that are not always obvious.

The Connection Between Protein and Amino Acids

Illustration showing protein digestion, with a chain of protein broken down by enzymes into individual amino acids.

Proteins are the building blocks for your body, and amino acids are the building blocks for proteins. (You can think of amino acids as the beads on a protein necklace.)

Proteins in food you eat are broken down into smaller amino acid groupings or individual amino acids. (You take the necklace apart.)

Those amino acids are then used for biochemical reactions or put back together in amino acid sequences to make the particular proteins your body needs. (You repurpose the beads to make necklaces, bracelets, earrings, etc.)

What are Essential Amino Acids?

Protein amino acids are divided into three categories: essential, non-essential, and conditional.

When essential is associated with a nutrient, it means that your body cannot produce it on its own. It has to be consumed. In other words, you must get it from your diet from food or supplements, or you don’t have it available for the biochemical reactions that need it. Tryptophan is an example of an essential amino acid.

Non-essential means your body can make it from component parts you ingest. For example: glutamate.

You can also make conditional amino acids, but illness, stress, or some other less-than-optimal conditions can limit the amount you can create and you would benefit from eating more of the actual amino acid. For example: glycine.

From a nervous system perspective, having the right amino acids available matters just as much as having enough protein overall.

How Amino Acids Affect Anxiety

A large percentage of your body is made of amino acids. They are used to create and maintain cells, and they participate in countless other biochemical reactions. When it comes to anxiety, their relationship to neurotransmitters is especially important.

Neurotransmitters help regulate how happy, alert, reactive, settled, or overstimulated you feel. Some are stimulating, meaning they increase activity in the nervous system. Others are calming, meaning they quiet things down.

Protein amino acids interact with neurotransmitters in several ways:

Some amino acids are neurotransmitters themselves.
Some are precursor components used to create neurotransmitters.
One is dual-purpose: it is both an actual neurotransmitter and a precursor to a neurotransmitter.

Amino Acids and Neurotransmitters

Four protein amino acids’ relationship to neurotransmitters:

Glycine is a calming neurotransmitter itself.
Tryptophan, famous for turkey dinner sleepiness, is a precursor for the calming neurotransmitter serotonin.
Glutamate is dual purpose: it is your body’s major stimulating neurotransmitter as is, and a precursor for your body’s most common calming neurotransmitter, GABA.
Aspartate is a stimulating neurotransmitter.

Here’s what the neurotransmitter production sequences look like (neurotransmitters are in bold):

Glycine
Tryptophan → 5-HTP → Serotonin → Melatonin
Glutamate → GABA
Aspartate

Because of these roles, amino acids can influence whether nervous system activity trends toward calm and recovery or toward stimulation and heightened reactivity.

Stimulating and Calming Neurotransmitter Activity

From an anxiety perspective, it may be helpful to optimize the intake of amino acids that provide calming neurotransmitters (glycine) or support their production (tryptophan), and reduce or monitor intake of those that are stimulating (glutamate and aspartate).

This does not mean that stimulating neurotransmitters are harmful. Your brain relies on them for focus, learning, and responsiveness. Problems tend to arise when stimulating activity consistently outweighs calming input, especially in people who are already stress vulnerable.

A Potential Negative Side-Effect of Aspartame Sweetener

The artificial sweetener aspartame is of particular concern when dealing with anxiety. Aspartame is 50% phenylalanine, 40% aspartate, and 10% methanol. Aspartate is a stimulating neurotransmitter, and aspartame has been implicated in increasing anxiety.

The Blood-Brain Barrier and Neurotransmitters

The brain is protected by the blood-brain barrier, which carefully regulates what can enter brain tissue from the bloodstream.

It appears that some neurotransmitters need to be created from component biochemicals in the brain because they can't readily cross this barrier in their whole form.

This is one reason food and supplement choices tend to influence neurotransmitter activity indirectly rather than acting as direct switches. It also helps explain why GABA supplements may have limited effects for some people, and why supporting the brain’s own production of GABA may be a more effective way to increase the amount of GABA in your brain.

Feed Your Calm: Anti-Anxiety Diet and Supplement Tips for Stress Resilience

I expand on what we’ve been discussing here in my book Feed Your Calm, with a deeper look at neurotransmitters and the physical processes involved in stress resilience, including research on supplementing GABA.