Are non-essential proteins made in the body?

December 23, 2025 •

3 min read

Over 300 grams of protein are built and broken down in the human body every day. Yes, your body can and does produce non-essential proteins, specifically by synthesizing their component non-essential amino acids internally. This crucial ability allows for robust protein production for vital bodily functions, even without obtaining these specific amino acids from your diet.

Quick Summary

The human body manufactures its own non-essential amino acids through metabolic processes, which are then used to build proteins. The intricate process of protein synthesis, involving transcription and translation, uses an available pool of amino acids, regardless of whether they were made internally or consumed. This ensures a consistent supply of proteins for crucial functions like tissue repair and immune response.

Key Points

Internal Synthesis: The body can produce non-essential amino acids internally using metabolic precursors, which are then used to build proteins.
Universal Process: The mechanism of protein synthesis (transcription and translation) is the same for all proteins, regardless of whether their amino acid components are essential or non-essential.
Metabolic Linkage: The synthesis of non-essential amino acids is directly linked to other metabolic cycles like glycolysis and the citric acid cycle.
Conditionally Essential Status: Some non-essential amino acids become conditionally essential during illness, injury, or high stress, when the body's demand for them exceeds its production capacity.
Vital Functions: Non-essential amino acids are crucial for many physiological processes, including collagen formation, neurotransmitter production, immune support, and antioxidant defense.

Yes, your body makes non-essential proteins

The simple answer is yes: your body produces the amino acids required to make non-essential proteins. The key distinction between essential and non-essential is not a measure of their importance, but rather of their source. Essential amino acids must be consumed through the diet because the body cannot synthesize them, whereas non-essential amino acids can be manufactured by the body using other metabolic precursors.

The building blocks: Amino acids

Proteins are long, complex chains made up of smaller units called amino acids. There are 20 standard amino acids that are used to build proteins, and these are categorized based on whether the body can produce them internally.

Non-essential amino acids: Your body can produce these on its own through various metabolic pathways. Examples include alanine, asparagine, and glutamine.
Essential amino acids: These nine amino acids cannot be synthesized by the body and must be acquired from food.
Conditionally essential amino acids: Under normal circumstances, the body can produce these. However, during times of stress, illness, or rapid growth, production may not keep up with demand, making dietary intake essential.

The protein manufacturing process

The creation of a protein, whether essential or non-essential, follows a universal process called protein synthesis. This multi-step cellular mechanism is the same for all proteins, regardless of where their amino acid building blocks originate.

Transcription: A section of DNA, known as a gene, is copied into a messenger RNA (mRNA) molecule inside the cell's nucleus.
Translation: The mRNA molecule travels out of the nucleus to a ribosome in the cytoplasm. The ribosome reads the mRNA sequence and, with the help of transfer RNA (tRNA) molecules, assembles a chain of amino acids according to the genetic instructions.
Folding: Once the amino acid chain is complete, it folds into a specific three-dimensional shape, which determines its function.

During this process, the cell draws from an amino acid pool, which contains a mix of both essential amino acids from the diet and non-essential amino acids synthesized internally. The ribosome does not distinguish between the source of the amino acids it needs to assemble the final protein.

How non-essential amino acids are made

The synthesis of non-essential amino acids occurs mainly in the liver, drawing on intermediates from key metabolic cycles like glycolysis and the citric acid cycle. One of the primary synthesis methods is a process called transamination, which involves transferring an amino group from one molecule to another.

Alanine: Synthesized from pyruvate, an end-product of glycolysis.
Aspartate: Made from oxaloacetate, an intermediate in the citric acid cycle.
Glutamate: Derived from alpha-ketoglutarate, another citric acid cycle intermediate.
Tyrosine: Synthesized from the essential amino acid phenylalanine.

Comparison of essential and non-essential amino acids


Feature	Essential Amino Acids (EAAs)	Non-Essential Amino Acids (NEAAs)
Source	Must be obtained from the diet.	Can be produced internally by the body.
Number	9 amino acids.	11 amino acids.
Role in Synthesis	Direct triggers for muscle protein synthesis.	Provide structural and metabolic support for proteins.
Dietary Requirement	Always required, as the body cannot produce them.	Not always required, but intake can be beneficial during stress.
Examples	Leucine, Lysine, Tryptophan.	Alanine, Glycine, Serine.

The importance of non-essential amino acids

Despite their name, non-essential amino acids are critically important for human health. They contribute to a wide range of vital functions.

Support for protein structure: They are fundamental building blocks of all proteins, including enzymes, hormones, and structural proteins like collagen and elastin.
Neurotransmitter production: Several non-essential amino acids, such as glutamic acid and tyrosine, are precursors for neurotransmitters that influence mood and brain function.
Metabolic processes: Non-essential amino acids participate in crucial metabolic cycles, including detoxification pathways and energy production.
Antioxidant defense: Cysteine is a key component of glutathione, the body's most powerful antioxidant, which protects cells from damage.
Immune function and healing: Glutamine and arginine, for example, play key roles in supporting immune function and speeding up wound healing, especially when the body is under stress.

Conclusion

The classification of proteins as non-essential is not an indicator of their importance but rather a testament to the body's remarkable metabolic capability. Your body is a highly efficient factory, producing the necessary non-essential amino acids from scratch to ensure a constant supply for the intricate process of protein synthesis. This internal manufacturing process works alongside a balanced diet, which supplies the essential amino acids that cannot be created internally, to keep all bodily systems functioning optimally. Understanding this fundamental process highlights how integrated and self-sufficient the human body's biochemical machinery truly is.

Frequently Asked Questions

The terms actually refer to amino acids, the building blocks of proteins. Essential amino acids cannot be made by the body and must come from your diet, while non-essential amino acids can be synthesized internally. Both types are equally important for creating the body's proteins.

The body synthesizes non-essential amino acids through metabolic pathways, primarily in the liver. It uses compounds like pyruvate, oxaloacetate, and alpha-ketoglutarate, which are intermediates of other metabolic processes, as starting materials.

While it's not strictly necessary for survival under normal conditions, consuming non-essential amino acids can be beneficial, especially during high stress, intense training, or illness. This is because the body's internal production might not meet the increased demand during these times.

These are amino acids that are typically non-essential but become essential under specific circumstances, such as illness, injury, or rapid growth. For example, glutamine and arginine are conditionally essential during severe illness or trauma.

The process of protein assembly is called protein synthesis. It involves two main steps: transcription, where a gene's DNA is copied into mRNA, and translation, where a ribosome reads the mRNA to link amino acids together in the correct sequence.

Yes, all proteins are built from a combination of the 20 standard amino acids, which includes both essential and non-essential types. The final composition and sequence determine the protein's specific shape and function.

Transamination is a biochemical reaction that involves the transfer of an amino group to a keto acid to form a new amino acid. It is a key mechanism used by the body to produce many of the non-essential amino acids internally.