Glycine

What Is Glycine?

The smallest amino acid there is: a single hydrogen atom where every other one carries a side chain. That makes it the only one with no left- or right-handed version. The body builds it from serine, so it is not an essential nutrient, though demand can outrun supply. There is 3,000 mg per serving.

How It Works in the Body

Glycine's smallness is its job. In collagen, every third residue is glycine, because only a hydrogen side chain fits the crowded center of the triple helix. Elsewhere it is raw material: one of the three amino acids in glutathione, the acyl acceptor in the first step of creatine synthesis, and, with succinyl-CoA, the opening move of heme synthesis. The liver also joins glycine to bile acids and to benzoate.

What It Supports

• Collagen structure: Glycine is every third residue along the collagen triple helix, a position no larger amino acid can occupy.
• Glutathione synthesis: Glycine is one of the three amino acids the body joins together to build glutathione.
• Restful sleep: Glycine is the main inhibitory neurotransmitter of the brainstem and spinal cord, and supports restful sleep.
• Bile salt formation: The liver attaches glycine to bile acids, which is how most human bile salts are made.

Who It May Suit

People eating mostly muscle meat, since glycine is concentrated in skin, tendon and bone rather than in a steak. It suits anyone whose diet is light on collagen-rich cuts, broths or gelatin, and anyone who wants a free-form amino acid with nothing else in the capsule.

Good To Know

A serving is three capsules, which is how a gram-scale amino acid fits a capsule people can swallow. Glycine tastes sweet, and that is where the name comes from. Talk with your provider before use if you take clozapine, since glycine acts at the same NMDA receptor site that medicine works through.