Principal Proposed Uses
Glycine is the simplest of the 20 different amino acids used as building blocks to make proteins for your body. It works in concert with glutamine, a substance that plays a major role in brain function. Glycine has shown some promise as an aid in the treatment of schizophrenia and may have other uses related to the brain as well, such as enhancing mental function .
Your body is able to make glycine using another amino acid, serine. Because you can manufacture glycine, you do not really have to consume any, so it is called a "nonessential amino acid." Most of us get about 2 g of glycine a day from the foods we regularly eat anyway. This dietary glycine comes mostly from high-protein foods like meat, fish, dairy products, and legumes. For treating certain disease conditions, however, much larger amounts than are normally consumed have been advocated; such high doses can only be obtained by taking supplements.
Dosages of oral glycine used in clinical trials for therapeutic purposes range from 2 to 60 g daily.
Manufacturers advertising glycine supplements have made a number of additional claims for it, including prevention of epileptic seizures , reducing acid in the stomach, multiple sclerosis , boosting the immune system , and calming the mind. It is also proposed as a sports supplement , said to work in this capacity by increasing release of human growth hormone (HGH). As yet, there is no real scientific evidence that glycine works for any of these purposes.
Because it has a sweet taste, glycine has also been recommended as a sugar substitute for people with diabetes.
What Is the Scientific Evidence for Glycine?
Glycine might enhance the effectiveness of drugs used for schizophrenia , especially those in the older phenothiazine category. It has also shown equivocal promise for the drugs risperidone and olanzapine. However, it may not be helpful for people using clozapine .
Phenothiazine drugs are most effective for the "positive" symptoms of schizophrenia, such as hallucinations and delusions. (Such symptoms are called "positive" because they indicate the presence of abnormal mental functions, rather than the absence of normal mental functions.) In general, however, these medications are less helpful for the "negative" symptoms of schizophrenia, such as apathy, depression, and social withdrawal. Glycine might be of benefit here.
No serious adverse effects from using glycine have been reported, even at doses as high as 60 g per day. One participant in the 22-person trial described above developed stomach upset and vomiting, but it ceased when the glycine was discontinued.
In addition, as noted above, it is possible that use of glycine could reduce the benefits of clozapine.
Maximum safe doses for young children, pregnant or nursing women, or people with liver or kidney disease are not known.
Interactions You Should Know About
If you are taking:
- Clozapine : Do not take glycine except on the advice of a physician.
- Reviewer: EBSCO CAM Review Board
- Review Date: 07/2012 -
- Update Date: 07/25/2012 -