Glycine
Aminoacetic acid
Supplements. Modern nutrition.
Also called Glycocoll, Gly
Pinyin: gān ān suān
Spanish: Glicina
The simplest amino acid, used by the body to build proteins, and often taken at bedtime to help with sleep.
Did you know? About one third of collagen, the protein in skin, bones and tendons, is glycine. That is why bone broth and gelatin are rich in it.
What it may help, and how strong the proof is
- Sleep. Small trials gave about 3 grams before bed. People with poor sleep reported better sleep quality, and healthy adults felt less tired the next day. The trials are small and short.See the research: 12 studies in peoplePromising proof
- Memory & focus. As an add-on to antipsychotic medicines for schizophrenia, glycine and the related amino acid D-serine showed some gains in negative symptoms, such as low motivation, in an older Cochrane review of short, small trials. Results conflict, and one later analysis found that glycine added to clozapine worsened positive symptoms.See the research: 104 studies in peoplePromising proof
Parts of the body
Traditional use
Glycine is not part of old herbal traditions. It was first identified in the early 1800s from gelatin, a protein made from animal collagen. It is now also used in some medical settings, such as in surgical rinsing fluids.
How it is classified
How people take it
Sleep studies used about 3 grams before bed. Some schizophrenia studies used higher amounts under medical supervision. Glycine from ordinary protein foods is part of a normal diet.
Powder, capsule and food.
Where to get it
Your body makes glycine from other amino acids. Food sources include gelatin, bone broth, meat, fish, dairy, soybeans and some seeds. Powder and capsules are sold in stores and online.
Be careful
Usually well tolerated. Large doses can cause an upset stomach, loose stools or nausea. People with kidney or liver disease should check with a doctor first. Schizophrenia use needs close medical care, since glycine may worsen positive symptoms when added to clozapine. Safety in pregnancy and breastfeeding is not well studied, so food sources are the safer choice unless a doctor advises a supplement.
Avoid if: pregnancy; breastfeeding; kidney disease; liver disease.
Mixing with other things
- Works well together
Magnesium glycinate pairs magnesium with glycine. Both are often sold as bedtime or relaxation supplements, and research on the pair is limited.
The honest take
Glycine is a normal part of food and body protein, so it is generally safe at typical doses. The sleep results are promising but come from small, short trials. Schizophrenia research is mixed, and that use should only happen with medical care.
Sources
Each “See the research” link opens PubMed, the U.S. National Library of Medicine's index of medical studies, showing only trials and reviews done in people. The number tells you how much a use has been tested, not whether it worked. The proof rating tells you that.
Study counts checked October 2026.