How Many Amino Acids Are Considered Nonessential?

December 16, 2025 •

2 min read

There are 20 different amino acids that the human body needs to function correctly. Of these 20, 11 are officially considered nonessential, meaning your body can synthesize them and they do not need to be obtained directly from your diet. This article breaks down the classifications and important functions of these vital molecules.

Quick Summary

The human body can synthesize 11 amino acids, classifying them as nonessential. While not required from dietary intake under normal conditions, they perform critical metabolic roles. Certain situations, like illness or stress, can render some nonessential amino acids conditionally essential, requiring temporary dietary supplementation.

Key Points

Eleven Nonessential Amino Acids: A total of 11 amino acids are categorized as nonessential because the body can produce them internally.
Conditionally Essential: Some nonessential amino acids can become conditionally essential during periods of stress, illness, or injury, when the body's production cannot meet demand.
Critical Bodily Functions: Nonessential amino acids play vital roles in protein synthesis, immune function, neurotransmitter production, and tissue repair.
Balanced Diet is Key: While nonessentials can be made by the body, a balanced diet is still important for providing the necessary precursors and co-factors for their synthesis.
Examples Include: Key nonessential amino acids include alanine, arginine, glutamine, and tyrosine, among others.

The Core Classifications of Amino Acids

Amino acids are the fundamental building blocks of proteins, performing vital functions like tissue building, hormone creation, and metabolic support. The 20 standard amino acids are categorized into essential, nonessential, and conditionally essential, based on whether the body can produce them or if they must come from diet.

The Eleven Nonessential Amino Acids

Eleven amino acids are typically nonessential for healthy adults. This term signifies they don't need to be consumed in the diet as the body can make them. {Link: Cleveland Clinic my.clevelandclinic.org/health/articles/22243-amino-acids} provides a list of these amino acids. These are synthesized from existing compounds in the body through metabolic pathways.

Conditionally Essential Amino Acids

Some nonessential amino acids are conditionally essential. While usually produced sufficiently by the body, during stress, illness, or growth, demand can exceed synthesis, requiring dietary intake. This group includes Arginine, Cysteine, Glutamine, Glycine, Proline, Serine, and Tyrosine.

The Nine Essential Amino Acids

The nine essential amino acids cannot be produced by the body and must come from the diet. These are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

A Comparison of Amino Acid Types


Feature	Essential Amino Acids	Nonessential Amino Acids	Conditionally Essential Amino Acids
Dietary Requirement	Must be consumed via diet	Not required via diet under normal circumstances	Required via diet only during stress, illness, or rapid growth
Synthesis by Body	Cannot be synthesized internally	Can be synthesized internally	Can be synthesized, but production is insufficient under certain conditions
Number	9	11	A subset of the nonessential amino acids (6 or more)
Examples	Leucine, Lysine, Tryptophan	Alanine, Aspartic Acid, Serine	Arginine, Glutamine, Tyrosine
Role	Foundation for all proteins	Critical for various metabolic and structural functions	Crucial for immune response and tissue repair during high demand

Roles and Importance of Nonessential Amino Acids

Nonessential amino acids are vital for various functions:

Protein Synthesis: Essential for creating new proteins, enzymes, and hormones.
Immune Support: Conditionally essential amino acids aid immune cell function during stress.
Neurotransmitter Production: Tyrosine, for example, is a precursor to dopamine and other neurotransmitters.
Metabolism & Detox: Alanine and glycine are involved in glucose metabolism and detoxification.
Tissue Repair: Proline and serine contribute to collagen synthesis for wound healing and skin health.

Conclusion

In summary, 11 amino acids are considered nonessential because the body can produce them. The classification is complicated by conditionally essential amino acids, needed from diet during times of high demand like stress or illness. A balanced diet supports the body's needs for both essential and nonessential types.

This article does not constitute medical advice. Consult a healthcare professional for dietary recommendations.

Frequently Asked Questions

A nonessential amino acid is one that the human body can synthesize on its own, meaning it does not need to be acquired directly from dietary sources under normal circumstances.

There are 11 amino acids that are considered nonessential for a healthy adult. You can find a list of these on {Link: Cleveland Clinic my.clevelandclinic.org/health/articles/22243-amino-acids}.

No, the term 'nonessential' refers only to the dietary requirement, not to their importance. These amino acids are crucial for many bodily functions, including protein synthesis, metabolism, and immune health.

Conditionally essential amino acids are typically nonessential, but become essential when the body is under stress, such as during illness, injury, or intense physical training. During these periods, the body's demand for them exceeds its production capacity.

This happens when a physiological stressor, like infection, trauma, or intense exercise, increases the body's metabolic demand for a specific amino acid faster than it can synthesize it. This shift makes dietary intake necessary to meet the higher demand.

Under normal conditions, you do not need to focus on specific dietary sources for nonessential amino acids, as your body will produce them. Eating a balanced diet with sufficient protein will provide both essential amino acids and the necessary building blocks for nonessential ones.

Nonessential amino acids are involved in producing proteins, enzymes, and hormones; regulating metabolic processes; supporting immune function; and aiding in tissue repair.