Amino acid
Glycine
Glycine is the simplest amino acid. The body can make it itself, and it is abundant in collagen and other protein-rich foods.
Also listed as 2-Aminoacetic acid, L-Glycine
Is collagen equivalent to glycine?
A 2026 scoping review examined both glycine and collagen supplements. Some trials reported sleep-related improvements, but the proposed idea that glycine explains collagen’s effects has not been tested directly. A gram of collagen should therefore not be treated as a tested gram of isolated glycine. 1
Which ingredient did a study actually test?
The GlyNAC trial supplied 100 mg/kg daily of each ingredient. Labels need both amounts for comparison; this was a monitored research regimen. 2