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There are 4 commonly used classifications for amino acids. Three of them respectively differentiate between standard vs. non-standard amino acids, proteinogenic vs. non-proteinogenic amino acids” or their chemical properties.
The most well-known way to classify amino acids is based on human health requirements.
Essential amino acids are called “essential”, because the human body cannot make (“synthesize”) them. The cells in all mammals lack the enyomes to create the molecule’s carbon skeleton.It is therefore essential that they are consumed through food in sufficient amounts. Eight are essential for adults, and infants require an extra two:
There are 4 commonly used classifications for amino acids. Three of them respectively differentiate between standard vs. non-standard amino acids, proteinogenic vs. non-proteinogenic amino acids” or their chemical properties.
The most well-known way to classify amino acids is based on human health requirements.
[*=center][h=4]Essential[/h]
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Essential amino acids are called “essential”, because the human body cannot make (“synthesize”) them. The cells in all mammals lack the enyomes to create the molecule’s carbon skeleton.It is therefore essential that they are consumed through food in sufficient amounts. Eight are essential for adults, and infants require an extra two:
- L-phenylalanine (essential to make L-tyrosine)
- L-valine
- L-threonine
- L-tryptophan
- L-isoleucine
- L-methionine (essential to make L-cysteine)
- L-histidine (essential for infants only)
- L-arginine (essential for infants only)
- L-leucine
- L-lysine
[*=center][h=4]Semi-essential[/h]
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Amino acids are semi-essential or “conditionally essential”, when they cannot be produced in sufficient amounts by the body. This can happen in special conditions, such as prematurity in infants or in individuals under severe catabolic distress (such as extreme hunger or crash diets).There are six semi-essential amino acids:
- L-arginine: Arginine is classified as a semi-essential, because born infants are unable to synthesize or create arginine internally, making the amino acid nutritionally essential for them. Additional supplementation has significant health benefits in adults.
[*]L-tyrosine: if not sufficiently consumed, the essential amino acid L-phenylalanine is used to make L-tyrosine.
[*]L-cysteine
[*]L-glycine
[*]L-glutamine
[*]L-proline
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[*=center][h=4]Non-essential[/h]
Five amino acids are non-essential for humans, because they can be synthesized in the body.
- L-alanine
- L-asparagine
- L-glutamic acid
- Asparagine
- L-serine
