Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show?

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7871530/

Creatine (methylguanidine-acetic acid) is endogenously formed from reactions involving the amino acids arginine, glycine and methionine in the kidneys and liver

Methyl (CH3)
Guanidine (Nitrogen)
Glycine (Glycerol)
Acetic Acid (Vinegar)
Magnesium

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Guanidinoacetic Acid (GAA)
Glycocyamine
Molecular Formula:
C3H7N3O2

Guanidinoacetic acid in human nutrition: Beyond creatine synthesis

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10084987/

https://www.livingwithmthfr.org/genetic-education/amino-acids/creatine-ck-cpk

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Tripeptide

https://en.m.wikipedia.org/wiki/Tripeptide

Copper peptide GHK-Cu

https://en.m.wikipedia.org/wiki/Copper_peptide_GHK-Cu

Ophthalmic acid

https://en.m.wikipedia.org/wiki/Ophthalmic_acid

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Guanidine

Guanidinoacetic acid (GAA, also known as glycocyamine or betacyamine) is a naturally-occurring derivative of glycine and a direct metabolic precursor of creatine

subjects with hypertension experienced transient reduced blood pressure in the combination of betaine and guanidinoacetate.

https://en.m.wikipedia.org/wiki/Guanidine