[ Essential Amino Acid ]
An amino acid considered and essential nutrient. That is, that an organism cannot endogenously synthesise and, therefore, must be acquired from dietary sources.
For humans, there are nine amino acids that are considered essential:
Histidine (H)
Isoleucine (I)
Leucine (L)
Lysine (K)
Methionine (M)
Phenylalanine (F)
Threonine (T)
Tryptophan (W)
Valine (V)
See: Non-Essential Amino Acid