Glycine

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 considerable promise for the treatment of schizophrenia, and may have other uses related to the brain as well.

Your body is able to make glycine using another amino acid, serine. Because you can manufacture glycine, you dont really have to consume any, so its 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 might be helpful; such high doses can only be obtained by taking supplements.

Dosages of oral glycine used in clinical trials for therapeutic purposes range from 2 g to 60 g daily.

Glycine has been tried as a supportive treatment for schizophrenia. Preliminary evidence suggests that high doses of glycine (from 15 to 60 g daily) combined with standard therapy can help with some aspects of this disease. Note: Although glycine appears to be helpful when combined with older drugs for schizophrenia, mixed evidence suggests that it might interfere with the action of newer antipsychotic medications. (See Safety Issues below.) One large double-blind study suggests that low doses of glycine may be helpful for limiting the spreading brain damage that occurs during stroke. However, there are also theoretical concerns that glycine could increase such damage (see Safety Issues), so you should not try this treatment except under physician supervision. One small study suggests that glycine may enhance memory and mental function. Studies performed in the 1950s and 60s suggested that a combination of glycine, alanine, and glutamic acid may be helpful for prostate enlargement. However, as this work does not meet modern research standards, the results can't be taken as reliable. Glycine alone and in combination with other amino acids has been studied as a topical treatment for wounds. A randomized, double-blind placebo-controlled study with 22 participants showed improvements in healing time and pain control. However, larger studies are necessary to validate these preliminary findings. Animal studies suggest that dietary glycine may protect against chemically-induced damage to the liver or kidneys, and possibly speed recovery from injury. Other studies in laboratory animals suggest that dietary glycine may prevent tumor formation and growth in the livers of mice and rats. However, it is too early to say whether glycine will prevent cancer in humans. Manufacturers advertising glycine supplements have made a number of additional claims for it, including prevention of epileptic seizures, reducing acid in the stomach, treating muscle spasticity (as in multiple sclerosis, MS), 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 both for people with diabetes and hypoglycemia. It is not known to have any sort of therapeutic effect for these conditions; the advantage lies only in that the person is not using sugar.

Schizophrenia Schizophrenia is not, as many people believe, a multiple personality disorder. Rather, it is a severe and probably genetic condition that causes such symptoms as hallucinations, delusions, thought disorders, social withdrawal, and blunted emotions. Various medications are used for schizophrenia with reasonably good results. However, they tend to be most effective for the positive symptoms of schizophrenia, such as hallucinations and delusions—these symptoms are called positive because they are the presence of abnormal mental functions, rather than the absence of normal mental functions. Medications are less helpful for the negative symptoms of schizophrenia, such as apathy, depression, and social withdrawal: glycine may be of benefit here. A clinical trial enrolled 22 participants with schizophrenic symptoms that were not well managed by medications alone. In this placebo-controlled double-blind crossover study, volunteers were randomly assigned to receive either 0.8 g per kg of body weight (about 60 g per day) of glycine or placebo for 6 weeks, along with their regular medications. The groups were then switched after a 2-week wash-out period during which they all received placebo. Significant improvements (about 30%) in symptoms such as depression and apathy were seen with glycine when compared to placebo. As a bonus, glycine also reduced some of the side effects caused by the prescription drugs. Furthermore, the benefits appeared to continue for another 8 weeks after the glycine was discontinued. No changes were seen in positive symptoms (for instance, hallucinations), but we dont know if that is because these symptoms were already being controlled by prescription medications or if glycine simply has no effect on that aspect of schizophrenia. Three earlier double-blind placebo-controlled clinical trials of glycine together with standard drugs for schizophrenia also found it to be helpful for negative symptoms. All of these studies used very small groups ( from 12 to 18 people), so much larger trials are still needed to verify glycines effectiveness. Glycine does not appear to be helpful for individuals using the newer antipsychotic drug clozapine, presumably because clozapine is very different from previous generation antipsychotics. Stroke Glycines usefulness for treating individuals who have undergone strokes was investigated in a double-blind placebo-controlled study with 200 participants. The results suggest that glycine can protect against the spreading damage to the brain that usually follows a stroke. Participants were given either 1 to 2 g of glycine sublingually (dissolved under the tongue) or placebo treatment for a period of 5 days. The results suggest that glycine can prevent neural damage. This appears to be an impressive result, but further research is necessary. Although other researchers using glycine for brain disorders have reported that such small doses of glycine would not be sufficient to cross the blood-brain barrier, measurements of amino acids in the cerebrospinal fluid during the above study suggest that it did enter the brain. However, there are potential concerns that high-dose glycine could increase stroke damage (see Safety Issues below).

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 contradiction to the study on strokes mentioned above, theoretical concerns have been raised that suggest glycine might actually increase brain injury in strokes. In fact, drugs that block glycine have been investigated as treatments to limit stroke damage. However, the authors of the study on strokes described above make an argument that suggests the overall effect of glycine is protective. Until this controversy is settled, prudence suggests not using glycine following a stroke, except on the advice of a physician. Another controversy involves glycine’s effects when it is combined with one of the newer antipsychotic drugs: clozapine. While glycine seems to work well with standard antipsychotic drugs, one double-blind, placebo-controlled trial suggests that it is not helpful and may even be harmful when combined with clozapine. In this study, glycine was found to reduce the benefits of clozapine without helping to relieve the participants negative symptoms. However, other evidence suggests that glycine does enhance clozapine’s effects; a conclusive analysis of this issue awaits further research. Maximum safe doses for young children, pregnant or nursing women, or people with liver or kidney disease are not known.

If you are taking clozapine, do not take glycine except on the advice of a physician.