Essential Amino Acids
The Compounds (9)
Histidine
The parent of histamine and a building block of hemoglobin and carnosine.
Read the deep dive →Isoleucine
A branched-chain amino acid (BCAA) that muscle can burn for fuel, with a role in glucose uptake.
Read the deep dive →Leucine
The branched-chain amino acid that switches on muscle protein building through the mTOR signal.
Read the deep dive →Lysine
Needed for collagen and carnitine, and best known for its use against cold sores (herpes simplex).
Read the deep dive →Methionine
The sulfur amino acid every protein chain starts with, and the source of SAM-e, the body’s main methyl donor.
Read the deep dive →Phenylalanine
The starting point for tyrosine and dopamine; it must be restricted in phenylketonuria (PKU).
Read the deep dive →Threonine
Built into collagen, elastin and the mucins that line and protect the gut.
Read the deep dive →Tryptophan
The precursor of serotonin, melatonin and niacin (vitamin B3).
Read the deep dive →Valine
The third branched-chain amino acid, used by muscle for energy and repair.
Read the deep dive →The nine the body cannot make at all, so they have to come from food. “Essential” is a statement about synthesis, not importance — a non-essential amino acid is no less necessary, the body just builds it itself. These nine are what protein quality is actually measured against.