When we think of protein, we immediately associate it with the growth of biceps and triceps, but these nutrients not only help us gain strength and muscle mass, they are also essential for our mental health. If we don’t consume enough, it will soon be noticeable in our mood, concentration, and even the way we cope with stress.
Proteins and neurotransmitters: the hidden relationship between food and the brain
Proteins are not simply building blocks for muscle; they are an essential source of amino acids, many of which act as precursors to neurotransmitters that regulate mood, attention, and memory. Without these amino acids, the synthesis of brain messengers like serotonin, dopamine, and norepinephrine would be compromised.
But let’s start from the beginning.
Neurotransmitters are chemical messengers in the brain that facilitate communication between neurons and, therefore, play a role in our psychological functions. However, they don’t appear out of thin air; rather, they are “manufactured” from specific protein components called amino acids.
Proteins are “gigantic” structures, so the brain cannot use them directly. First, they must undergo a hydrolysis process in which the bonds of the protein chains are broken down to transform them into smaller peptides and amino acids that can then enter the bloodstream.
Once in the bloodstream, they cross the blood-brain barrier and reach the neurons, where different neurotransmitters (dozens of them) are produced and stored in synaptic vesicles. When an electrical signal reaches the neuron, this vesicle opens, releasing the corresponding neurotransmitter and transmitting the nerve impulse. This process allows you to feel calm, react quickly to a dangerous situation, concentrate on a task, or be motivated to undertake a project, among countless other functions.
Obviously, if you don’t consume enough protein, your body won’t be able to generate all the amino acids and neurotransmitters it needs, or at least not in the right amount for the brain and nervous system to function normally, which will end up affecting your mental health in different ways.
Emotional low and depression
Without protein there is no tryptophan, and without tryptophan the brain cannot produce serotonin . When serotonin levels drop, mood often deteriorates, so you are likely to feel sadder, more apathetic, tired, and lacking in energy.
In fact, a study conducted with more than 17,000 people concluded that “Total protein intake, especially milk and dairy proteins, may reduce the risk of developing depressive symptoms.”
On the other hand, a dopamine deficiency, which is synthesized from the amino acids tyrosine and phenylalanine present in proteins, can also cause anhedonia. That is, sinking into that dull feeling where nothing excites, amuses, or inspires you.
The constant buzzing of anxiety
Serotonin isn’t just the “happiness hormone”; it also acts as a kind of “handbrake” in the brain. Without enough of this protein, that inhibition can fail. Essentially, serotonin plays a role in emotional regulation, softening reactions to stimuli and acting as a buffer against impulsivity and anxiety.
Therefore, when your body doesn’t produce enough of it, not only does impulsivity increase, but frustration tolerance also decreases. You may become hypervigilant and irritable, and react more intensely, which ultimately fuels anxiety.
It is no coincidence that research conducted at Nanjing Agricultural University found that dietary protein influences serotonin biosynthesis, a deficiency of which has been linked to a higher risk of anxiety.
Feeling overwhelmed and stressed
In 2009, researchers at Maastricht University asked themselves: can what we eat before a difficult moment influence how we deal with stress? They found that consuming foods rich in tryptophan before exposure to stressful tasks not only improved mood but also lowered the level of cortisol in the blood, the stress hormone.
In fact, when you’re stressed, your body uses amino acids more quickly to produce cortisol and adrenaline. If you don’t replenish these by increasing the protein in your diet, your brain is likely to go into “alarm mode” because it lacks the raw materials it needs to produce inhibitory neurotransmitters (like GABA), which balance the stress response by helping to regulate emotions and restore calm.
This means that what you used to handle discreetly and efficiently now seems like an impossible mission. Your nervous system will be more reactive, so even minor setbacks will feel like a huge problem, and anything will overwhelm you.
The “brain fog” that prevents you from thinking
To concentrate, you need dopamine and norepinephrine, which are produced from the amino acids tyrosine and phenylalanine. Without them, communication between neurons slows down.
In practice, this means you’ll struggle to think clearly, you might misplace your keys, or you might read a page but not understand anything. You’re not just losing mental agility; you could even experience brain fog, a feeling of confusion where you can’t grasp ideas.
Furthermore, proteins also play a role in regulating brain energy metabolism, so a deficiency in them causes neurons to work less efficiently. The brain enters “energy-saving mode,” which contributes to cognitive fatigue and a feeling of being sluggish – a state that will eventually affect your well-being if it persists over time.
An emotional rollercoaster
Proteins also affect our mood in another way, acting as a kind of buffer against glucose. When you eat carbohydrates (bread, sweets, pastries, or soft drinks), glucose enters the bloodstream very quickly. Without protein, glucose levels spike, your body releases insulin, and then the sugar drops rapidly, causing a crash. As a result, you can go from feeling energetic to tired, irritable, and nervous in just a few hours.
Proteins, on the other hand, can slow down sugar absorption and cause glucose levels to rise gradually, thus helping to stabilize mood. This allows the brain to function in a more predictable environment, facilitating emotional regulation and greater mental clarity.
This energy stability translates into emotional stability: more patience, greater stress tolerance, and fewer impulsive reactions. In fact, it’s no coincidence that research has shown that frequent blood sugar crashes affect brain areas involved in self-control and decision-making, such as the prefrontal cortex.
How to use protein to feel better?
Taking care of your emotional balance and mental health isn’t just about meditating or trying to relax with breathing exercises or yoga when you’re feeling overwhelmed. Self-care also starts with what you eat, and protein plays a key role.
The good news is that you don’t need to become a nutrition expert; you just need to make small changes to your diet to boost your protein intake if you’re not consuming enough.
First, think about varied sources of quality protein. This isn’t just about meat or fish. Eggs and dairy products, and even legumes, nuts, and seeds, also provide essential amino acids that your brain needs.
In fact, if you don’t want to consume animal protein, you should know that there are excellent alternatives, such as pea protein, which has a very balanced profile. It provides amino acids like tryptophan, a direct precursor to serotonin, as well as phenylalanine and tyrosine, essential for the production of dopamine and norepinephrine, not to mention glutamine, essential for the formation of glutamate, which is involved in neuronal excitation. And half a serving of peas has almost as much protein as a whole egg, according to the Spanish Nutrition Foundation.
Consider every meal an opportunity to include at least one source of protein. For example, you could make scrambled eggs for breakfast, add a handful of nuts to your salad, opt for plain yogurt for dessert, keep protein-rich snacks on hand to munch on when you feel hungry, or make yourself a protein shake after your workout.
The key lies in integrating these changes into your daily life as just another healthy habit, so that you give your mind what it needs to perform and stay balanced, just as you would with any other self-care routine.
References:
Li, Y.et. Al. (2020) Association between dietary protein intake and the risk of depressive symptoms in adults. Br J Nutr; 123(11): 1290-1301.
Xie, Y. et. Al. (2020) Dietary Proteins Regulate Serotonin Biosynthesis and Catabolism by Specific Gut Microbes. J Agric Food Chem; 68(21): 5880-5890.
Xia, W. et. Al. (2020) Glucose Fluctuations Are Linked to Disrupted Brain Functional Architecture and Cognitive Impairment. J Alzheimers Dis; 74(2): 603-613.
Firk, C. & Markus, C. R. (2009) Mood and cortisol responses following tryptophan-rich hydrolyzed protein and acute stress in healthy subjects with high and low cognitive reactivity to depression. Clin Nutr; 28(3): 266-271.
Reimold, M.et. Al. (2008) Anxiety is associated with reduced central serotonin transporter availability in unmedicated patients with unipolar major depression: a [11C]DASB PET study. Mol Psychiatry; 13: 606-613.
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