How do I know if my amino acids are low?

November 1, 2025 •

5 min read

According to the National Institutes of Health, severe protein deficiency is rare in developed countries, but low intake of essential amino acids can occur due to various factors and lead to noticeable health problems. This can cause many to wonder, 'How do I know if my amino acids are low?'

Quick Summary

Amino acid deficiency symptoms often include fatigue, muscle weakness, mood changes, and compromised immune function. Medical diagnosis is done through blood and urine tests. Causes range from poor diet to digestive issues and chronic disease. Treatment focuses on a protein-rich diet and supplements, depending on the severity.

Key Points

Persistent Fatigue: Unexplained and ongoing tiredness may signal that your body lacks sufficient amino acids for energy production.
Muscle Weakness and Loss: The body may break down muscle tissue to supply essential amino acids if intake is low, leading to reduced muscle mass and strength.
Mood Swings and Cognitive Decline: Low levels of amino acids can affect neurotransmitter production, potentially causing mood changes, anxiety, and 'brain fog'.
Compromised Immunity: A deficiency can weaken the immune system, making you more susceptible to illness and slowing down recovery.
Diagnostic Testing is Necessary: Blood and urine tests ordered by a healthcare provider are the most accurate way to confirm a deficiency and determine the right course of action.
Increase High-Quality Protein: To address a deficiency, incorporate diverse protein sources, including animal-based or carefully combined plant-based foods, into your daily diet.

Amino acids are fundamental to our bodies, serving as the building blocks for proteins that are critical for nearly every physiological function, including hormone production, tissue repair, and immune response. When your intake or absorption of amino acids is insufficient, your body can't perform these functions optimally, leading to a range of symptoms. Since amino acids are not stored for long periods, a consistent intake of high-quality protein is necessary to avoid deficiency.

Recognizing the Symptoms of Low Amino Acids

Recognizing a potential amino acid deficiency starts with paying attention to your body. While these signs can overlap with other health conditions, persistent issues may warrant a conversation with a healthcare provider.

Physical signs of deficiency

Fatigue and weakness: Feeling constantly tired or lacking energy, even after sufficient sleep, can be a major indicator. Amino acids are crucial for energy production, and low levels can leave you feeling sluggish and unmotivated.
Muscle loss and weakness: The body may break down muscle tissue to acquire essential amino acids for more critical functions when dietary protein is insufficient. This can lead to a decrease in muscle mass and overall weakness.
Slow wound healing: Amino acids are necessary for collagen synthesis, a vital component of skin and connective tissues. A deficiency can impair the body's ability to repair tissues, leading to longer healing times for injuries.
Brittle hair, skin, and nails: A lack of protein can first show up in your hair, skin, and nails, making them brittle or thin. This is because these tissues rely on amino acids for their structure.
Edema (swelling): In severe cases of protein-energy malnutrition, low levels of albumin—a protein that helps regulate fluid balance—can lead to fluid retention and swelling, particularly in the extremities.

Mental and emotional signs

Mood changes: Amino acids are precursors to important neurotransmitters like serotonin and dopamine, which regulate mood. Low levels, particularly of tryptophan, can lead to mood swings, anxiety, or depression.
Memory problems and "brain fog": Difficulty concentrating, mental fatigue, or memory issues can arise from a lack of neurotransmitter production, which is dependent on amino acids.
Sleep disturbances: Certain amino acids, such as tryptophan, are necessary for producing hormones that regulate sleep, like melatonin. A deficiency can cause problems with sleep patterns.

Other indicators

Compromised immune system: Amino acids are vital for immune function. A weakened immune response can make you more susceptible to infections and slow down recovery.
Digestive issues: Protein is necessary for producing enzymes that aid digestion. Insufficient protein intake can disrupt digestive processes, leading to problems like bloating or poor nutrient absorption.

How is an amino acid deficiency diagnosed?

If you suspect an amino acid deficiency, self-diagnosis is not reliable. A healthcare provider can perform diagnostic tests to get a clear picture of your nutritional status. The primary method for diagnosis is through blood and urine analysis.

Blood tests: A plasma amino acids test measures the levels of individual amino acids in your blood. This is often done after a fasting period to provide an accurate baseline reading. It's the most common and scientifically validated method for assessing amino acid status.
Urine tests: A 24-hour urine collection can be used to assess amino acid levels and detect abnormalities in how the kidneys excrete them. Since the kidneys usually maintain essential amino acid levels in the body, changes can show up in urine earlier than in blood.
Further investigation: In cases where an inherited metabolic disorder is suspected, more specialized tests, such as mass spectrometry, may be used. These tests are more common in diagnosing pediatric cases but can be useful for adults with certain presenting features.

Causes of low amino acids

Several factors can contribute to low amino acid levels, beyond just insufficient dietary protein intake:

Poor diet: Not consuming enough high-quality protein from sources like meat, fish, eggs, dairy, or complementary plant-based sources can lead to a deficiency.
Digestive issues: Conditions that impair digestion and absorption, such as celiac disease, chronic diarrhea, or low stomach acid, can prevent the body from breaking down proteins into amino acids effectively.
Aging: As we get older, stomach acid levels tend to decrease, which can hinder protein digestion. The body's ability to synthesize proteins also becomes less efficient.
Chronic illness and stress: Periods of chronic illness, high stress, or infection can increase the body's demand for amino acids, potentially outpacing supply.
Intense exercise: Athletes or individuals engaged in intense training have higher protein turnover and may need increased intake to prevent muscle breakdown.

Comparison: Complete vs. Incomplete Protein Sources

Ensuring you get all nine essential amino acids is key. Complete protein sources provide all of them, while incomplete ones lack one or more. Combining different incomplete proteins throughout the day can ensure you get a full profile.


Feature	Complete Proteins	Incomplete Proteins
Source Type	Primarily animal-based	Primarily plant-based
Amino Acid Profile	Contains all nine essential amino acids	Lacks one or more essential amino acids
Examples	Meat, poultry, fish, eggs, dairy, soy (edamame, tofu), quinoa	Beans, nuts, seeds, grains, and most vegetables
Dietary Strategy	Easy to meet needs with a varied diet	Requires combining different plant sources throughout the day
Consideration for Vegans/Vegetarians	Must carefully combine plant sources to achieve a full profile	The primary sources of protein for these diets

What to do if your amino acids are low

If diagnostic tests confirm a deficiency, treatment typically involves dietary and lifestyle changes under medical supervision.

Increase protein intake: Prioritize foods rich in complete proteins like meat, fish, eggs, and dairy. For vegans and vegetarians, focus on combining complementary plant proteins like rice and beans, or incorporate complete plant protein sources like soy and quinoa.
Consider supplements: In some cases, a healthcare provider may recommend essential amino acid (EAA) supplements to help fill nutritional gaps, especially when dietary intake is challenging or absorption is poor.
Address underlying issues: Working with a doctor to address any digestive disorders or chronic illnesses is crucial for long-term correction of a deficiency.

Conclusion

Monitoring your body for symptoms like persistent fatigue, muscle weakness, mood changes, and compromised immunity is the first step toward answering the question, 'How do I know if my amino acids are low?' However, because these symptoms are non-specific, a definitive diagnosis requires medical testing. By consulting a healthcare provider and implementing strategic dietary and lifestyle changes, you can address potential deficiencies and restore your body's essential functions. For further reading on the biochemistry of amino acids, the NCBI provides detailed scientific overviews.(https://www.ncbi.nlm.nih.gov/books/NBK557845/)

Frequently Asked Questions

The fastest and most reliable way to confirm an amino acid deficiency is through a blood test performed by a healthcare provider. While observing symptoms like fatigue and muscle weakness can indicate a problem, medical testing provides a definitive diagnosis.

Common symptoms include persistent fatigue, muscle weakness, mood swings, anxiety, poor concentration, and a compromised immune system leading to frequent infections. In more severe cases, issues like hair loss, skin problems, and fluid retention may occur.

Yes, low amino acids can significantly impact mental health. Amino acids like tryptophan are precursors to neurotransmitters such as serotonin and dopamine. A deficiency can lead to mood disorders, anxiety, depression, and memory problems.

Causes include insufficient protein intake from a poor diet, impaired protein digestion due to low stomach acid or chronic illness, reduced absorption with age, and increased metabolic demand during chronic stress or illness.

To increase amino acid levels naturally, consume a variety of high-quality protein sources. This includes complete proteins like meat, fish, eggs, dairy, and soy. Plant-based diets should focus on combining different legumes, nuts, and grains to get all essential amino acids.

Yes, you can get all nine essential amino acids on a plant-based diet. While most single plant sources are 'incomplete,' consuming a variety of plant proteins like beans, grains, nuts, and seeds throughout the day provides all essential amino acids. Complete plant proteins like soy and quinoa also exist.

For most healthy individuals with a balanced diet, supplements are not necessary. However, a healthcare provider might recommend essential amino acid (EAA) supplements for those with poor absorption, restricted diets, or specific medical conditions.