Mnemonic

Essential Amino Acids

A mnemonic for the nine essential amino acids.

Expansion

PVT TIM HaLL: Phenylalanine, Valine, Threonine, Tryptophan, Isoleucine, Methionine, Histidine, Leucine, Lysine

Expansion

PVT TIM HaLL:

  • P - Phenylalanine
  • V - Valine
  • T - Threonine
  • T - Tryptophan
  • I - Isoleucine
  • M - Methionine
  • H - Histidine
  • L - Leucine
  • L - Lysine

Conditionally essential in illness, prematurity or specific disease: arginine, cysteine, glutamine, tyrosine, glycine and proline. Tyrosine becomes essential in phenylketonuria, since it is normally made from phenylalanine.

Branched chain amino acids are leucine, isoleucine and valine; they are metabolised in muscle rather than liver, which is why they are used in liver failure formulations.

Ketogenic only: leucine and lysine (the two Ls), which cannot form glucose. Glucogenic and ketogenic: phenylalanine, isoleucine, threonine, tryptophan and tyrosine. All the rest are purely glucogenic.

Protein quality depends on the essential amino acid profile: animal proteins are complete, while most single plant proteins are limited in one, typically lysine in cereals and methionine in legumes, which is why combining them is nutritionally complementary.