Conditional Amino Acids

Arginine

Conditionally essential amino acid; precursor for creatine and nitric oxide synthesis

Citrulline

Non-protein amino acid that contributes to arginine and nitric oxide pathway context

Cysteine

Sulfur amino acid made from methionine. Food tables report cystine. Mapped to glutathione assembly with the formula-diet limits.

Glutamate

Amino acid and the substrate of GAD and of the first step of glutathione assembly. Intracellular roles are not a requirement to eat glutamate.

Glutamine

Amino acid used by enterocytes. Adult trials do not show a general permeability benefit. A postinfectious IBS supplement result stays in that group.

Glycine

Nonessential amino acid in collagen-rich foods. Substrate of glutathione assembly. Trials of glycine taken alone report psychiatric-symptom changes and small, high-bias sleep findings.

Serine

Amino acid condensed with homocysteine by cystathionine beta-synthase. Diet and endogenous synthesis can both supply it.

Tyrosine

Dopamine and norepinephrine precursor; LAT1 competition with LNAAs