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Which amino acids can the human body make on its own?

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Why our bodies need proteins — Amino acid The structure and function of amino acids.

The human body can synthesize several amino acids on its own, which are classified as either nonessential or conditionally indispensable depending on the circumstances.

Nonessential Amino Acids

These amino acids can be synthesized by the human body in sufficient quantities for normal health and growth. They include:123
* Alanine4
* Asparagine4
* Aspartic acid4
* Glutamic acid4
* Serine4

Conditionally Indispensable Amino Acids

The body can also synthesize these amino acids, but they may become essential under specific conditions, such as during certain life stages, illness, or when precursors are limited. These include:34
* Arginine4
* Cysteine4
* Glutamine4
* Glycine4
* Proline4
* Tyrosine4

In contrast, the nine essential amino acids—histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine—cannot be synthesized by the body and must be obtained through the diet.34