What is glycine?
Glycine is an amino acid with a number of important functions in the body. Glycine acts as a neurotransmitter, a component of collagen, and as a precursor to various biomolecules (e.g., creatine, heme), among other roles. Glycine is often considered conditionally essential, meaning it can usually be produced in the body in sufficient amounts. However, in certain contexts (e.g., pregnancy) more glycine may be needed from the diet. Glycine is found in most protein sources, meaning common sources of glycine include meat, eggs, soybeans, lentils, and dairy products.
What are glycine’s main benefits?
A few studies have found supplementation with glycine can improve sleep quality, with subsequent benefits to cognitive function. High doses of glycine have been shown to improve symptoms of schizophrenia. Glycine may reduce the blood glucose response to carbohydrate ingestion.
Glycine is a major component of collagen (around 25% by weight) and for this reasons is often taken to improve joint health, but human evidence in this area is currently lacking.
What are glycine’s main drawbacks?
In high amounts, glycine supplementation can cause gastrointestinal symptoms, including nausea and abdominal pain.
How does glycine work?
Glycine supplementation likely works through different mechanisms depending on the outcome of interest.
Glycine is a co-agonist of N-methyl-D-aspartate (NMDA) receptor, meaning glycine plays a role in activating this receptor in the brain. Glycine’s effect on the NMDA receptor has been proposed as underlying the improvements in both sleep and symptoms of schizophrenia with supplementation.
Glycine may benefit sleep by lowering core body temperature, as a warm body temperature can adversely affect sleep quality.
What are other names for Glycine
- 2-Aminoacetic acid
Dosage information
For glycemic and sleep benefits, doses of 3-5 grams with meals and before bed, respectively, have been used successfully in clinical research.
Examine Database: Glycine
Research FeedRead all studies
Research Breakdown
Examine Database References
- Sleep Quality - Kentaro Inagawa, Takenori Hiraoka, Tohru Kohda, Wataru Yamadera, Michio TakahashiSubjective effects of glycine ingestion before bedtime on sleep qualitySleep and Biological Rhythms.()
- Sleep Quality - Wataru Yamadera, Kentaro Inagawa, Shintaro Chiba, Makoto Bannai, Michio Takahashi, Kazuhiko NakayamaGlycine ingestion improves subjective sleep quality in human volunteers, correlating with polysomnographic changesSleep and Biological Rhythms.()
- Sleep Quality - Bannai M, Kawai N, Ono K, Nakahara K, Murakami NThe effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteersFront Neurol.(2012 Apr 18)
- Schizophrenia symptoms - Heresco-Levy U, Ermilov M, Lichtenberg P, Bar G, Javitt DCHigh-dose glycine added to olanzapine and risperidone for the treatment of schizophreniaBiol Psychiatry.(2004 Jan 15)