How to remember conditionally essential amino acids?

November 24, 2025 •

4 min read

According to MedlinePlus, conditionally essential amino acids are normally not required from the diet, but become vital during times of illness or stress. This guide will help you learn how to remember conditionally essential amino acids using simple memory aids and practical examples.

Quick Summary

Mastering the list of conditionally essential amino acids is key for many health students and professionals. This comprehensive guide provides effective mnemonics, explains each amino acid's role, and compares conditionally essential to other amino acid types.

Key Points

Mnemonic for Recall: A simple way to remember the list is Always Celebrate Good Grades, Perhaps Soon Tomorrow, for Arginine, Cysteine, Glutamine, Glycine, Proline, Serine, and Tyrosine.
Function of Arginine: Critical during trauma and rapid growth, it's a precursor for nitric oxide, which helps with blood flow and healing.
Role of Glutamine: Essential for immune cells and maintaining a healthy gut lining during illness and stress.
Importance of Tyrosine: While normally made from phenylalanine, it becomes essential for those with metabolic disorders like PKU or under high-stress conditions.
Cysteine's Antioxidant Power: This amino acid is a key building block for glutathione, one of the body's main antioxidants.
Conditions for Essentiality: These amino acids are crucial when the body's metabolic needs exceed its capacity for synthesis, such as during intense exercise, recovery from injury, or illness.
Impact on Athletes: Intense training can deplete certain conditionally essential amino acids, making supplementation important for recovery and performance.
Source Precursors: The availability of other amino acids, like methionine for cysteine and phenylalanine for tyrosine, determines if the body can synthesize them.

The Basics of Conditionally Essential Amino Acids

Amino acids are the building blocks of protein, and they are typically categorized as either essential (must be obtained from food) or non-essential (the body can produce them). Conditionally essential amino acids represent a third, nuanced category. These are amino acids that the body can normally synthesize, but during specific physiological states or stressors—like illness, injury, or intense growth—the body's demand can outpace its production. Understanding this distinction is fundamental before diving into memorization techniques.

List of Conditionally Essential Amino Acids

The most commonly cited list of conditionally essential amino acids includes: Arginine, Cysteine, Glutamine, Glycine, Proline, Serine, and Tyrosine.

Arginine (Arg): Becomes essential during periods of rapid growth (infancy) or recovery from trauma, burns, and other critical illnesses. It is a precursor for nitric oxide, which is important for circulation.
Cysteine (Cys): A sulfur-containing amino acid, its synthesis depends on an adequate supply of the essential amino acid methionine. It is a precursor for glutathione, a powerful antioxidant.
Glutamine (Gln): Essential during trauma, sepsis, and major surgery to fuel immune cells and maintain gut integrity.
Glycine (Gly): Used in the synthesis of many molecules, including creatine, collagen, and glutathione. Requirements increase during rapid growth or stress.
Proline (Pro): Crucial for collagen synthesis and wound healing. Production is overwhelmed during periods of intense repair or growth.
Serine (Ser): Involved in cell proliferation and immune function. Its synthesis is often insufficient during intense physiological stress.
Tyrosine (Tyr): Synthesized from the essential amino acid phenylalanine. Becomes conditionally essential in individuals with metabolic disorders like phenylketonuria (PKU) or during high-stress states.

Memorization Techniques for Conditionally Essential Amino Acids

Remembering this list can be challenging, but using a mnemonic device can make it much easier. Here is a simple, effective mnemonic: Always Celebrate Good Grades, Perhaps Soon Tomorrow.

Always: Arginine
Celebrate: Cysteine
Good: Glutamine
Grades: Glycine
Perhaps: Proline
Soon: Serine
Tomorrow: Tyrosine

Another approach is to break down the amino acids into smaller, more manageable groups based on their functions or precursors. This builds a deeper understanding alongside memorization.

The 'Stress' Group

This group focuses on the amino acids most critical during physiological stress and injury:

Arginine: Arginine for activists dealing with high stress.
Glutamine: Glutamine for gut health and great immunity.

The 'Building Block' Group

These amino acids are crucial for building and repairing tissues:

Proline: Proline for pro-collagen.
Glycine: Glycine for gelatin and grand structures.
Cysteine: Cysteine for connective tissue and antioxidant support (think of its sulfur).

The 'Special Case' Group

These are conditional based on specific precursors or metabolic states:

Tyrosine: Tyrosine from phenylalanine. Remember that if phenylalanine is low, tyrosine becomes essential.
Serine: Serine from glycolysis intermediate. Needed for nerve and immune cell signaling.

Comparison: Essential vs. Conditionally Essential Amino Acids


Feature	Essential Amino Acids (EAAs)	Conditionally Essential Amino Acids (CEAAs)
Source	Must be obtained through diet.	Body can synthesize, but demand may exceed supply under certain conditions.
Production	Not produced by the body.	Produced by the body, but production is limited during high-stress states.
Example Conditions	Necessary for all bodily functions and protein synthesis.	Critical during illness, injury, intense training, or rapid growth.
Dietary Importance	Always required in the diet.	Can be produced internally, but dietary or supplemental intake is vital under stress.
List Examples	Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine.	Arginine, Cysteine, Glutamine, Glycine, Proline, Serine, Tyrosine.

Why This Distinction Matters for Health and Recovery

For most healthy adults, the non-essential and conditionally essential amino acids are adequately produced by the body. However, for athletes, individuals recovering from surgery, or those with chronic illnesses, dietary or supplemental intake of CEAAs becomes critical. For instance, someone recovering from severe burns requires a massive amount of arginine for wound healing, and their body's normal production is insufficient. Similarly, gut health and immunity are heavily dependent on glutamine, which is often depleted during intense physical or psychological stress. Athletes undergoing heavy training blocks also benefit from prioritizing CEAAs to support recovery and reduce muscle breakdown.

Conclusion

Learning how to remember conditionally essential amino acids is a key step for anyone in the fields of nutrition, medicine, or athletic training. The best way to achieve this is by combining effective mnemonics like 'Always Celebrate Good Grades, Perhaps Soon Tomorrow' with an understanding of each amino acid's specific role. By recognizing that these amino acids become essential during high-demand periods, you can make more informed decisions about diet and supplementation, particularly during times of stress, illness, or recovery. This knowledge provides a powerful tool for optimizing health and performance when it matters most.

What to Remember

The mnemonic ACGGPST can effectively list the conditionally essential amino acids: Arginine, Cysteine, Glutamine, Glycine, Proline, Serine, Tyrosine.
Arginine becomes essential during periods of rapid growth and healing from trauma.
Glutamine is critical for immune function and gut health, especially under stress.
Cysteine is crucial for antioxidant defenses via glutathione synthesis.
Proline and Glycine are both vital for collagen and connective tissue repair.
Tyrosine's conditionally essential status often relates to conditions like PKU or high-stress demands.

Frequently Asked Questions

Non-essential amino acids can be synthesized by the body in sufficient amounts at all times, whereas conditionally essential amino acids can also be synthesized, but their production becomes insufficient during specific physiological stressors like illness, injury, or rapid growth.

Tyrosine becomes a conditionally essential amino acid for people with Phenylketonuria (PKU). This is because they cannot properly metabolize phenylalanine to produce sufficient tyrosine.

Arginine is conditionally essential because while healthy adults can produce enough, the body's demand increases significantly during periods of rapid growth (infancy), trauma, burn injuries, or specific diseases.

A straightforward mnemonic is 'Always Celebrate Good Grades, Perhaps Soon Tomorrow'. Each capitalized word corresponds to the first letter of a conditionally essential amino acid: Arginine, Cysteine, Glutamine, Glycine, Proline, Serine, and Tyrosine.

For most healthy individuals with a balanced diet, supplementation is not necessary. However, under specific conditions such as illness, injury, or intense athletic training, supplementation may be beneficial to meet increased demand and support recovery.

During illness, the immune system's activity increases, which significantly raises the body's need for glutamine. It serves as a vital fuel source for immune cells and helps protect the integrity of the gut lining.

Yes, glycine and proline are important for athletes, especially during recovery. Both are integral to collagen synthesis, which is essential for repairing connective tissues, tendons, and ligaments after intense training.