** Type II collagen is the major structural component present in connective tissues and is rich in amino acids glycine and proline. (vitalproteins.com)
Magnesium glycinate — Magnesium mixed with amino acid glycine is one of the best absorbable forms of magnesium. (supernutritionlife.com)
Gelatin is unusually high in the non-essential amino acids glycine and proline, (i.e., those produced by the human body), while lacking certain essential amino acids (i.e., those not produced by the human body). (mommypotamus.com)