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Glycine is a nonessential amino acid used by the body to build proteins. It is present in considerable amounts in prostate fluid.
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1 Star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.
This supplement has been used in connection with the following health conditions:
0.8 grams for every 2.2 lbs (1 kg) of body weight under medical supervision
Supplementing with glycine appears to help improve depression and mental symptoms and may reduce symptoms in people unresponsive to drug therapy.
There have been several reports of glycine reducing the symptoms of people with schizophrenia who were unresponsive to drug therapy.1 Large amounts of glycine (0.8 gram per 2.2 pounds of body weight per day) have been shown to reduce negative symptoms of schizophrenia and improve psychiatric rating scores in one preliminary trial;2 however, these results have not been repeated in later trials using similar (very high) amounts.3 , 4 Earlier double-blind trials found significant improvements in depression and mental symptoms in people with schizophrenia who took glycine for six weeks.5 , 6 Most trials demonstrated a moderate improvement in schizophrenia symptoms in those taking glycine supplements.7 Long-term supplementation with high amounts of glycine may be toxic to nerve tissue, however. Some preliminary successes have been reported using smaller amounts of glycine, such as 10 grams per day.8 Long-term studies on the safety of glycine therapy are needed.
How It Works
How to Use It
Healthy people do not need to supplement with glycine. A physician should be consulted before supplemental glycine is used for the support of serious health conditions.
Where to Find It
Glycine is found in many foods high in protein, such as fish, meat, beans, and dairy.
Few people are glycine deficient, in part because the body makes its own supply of the nonessential amino acids.
Interactions with Supplements, Foods, & Other Compounds
Interactions with Medicines
Certain medicines interact with this supplement.
Replenish Depleted Nutrients
Reduce Side Effects
Two double-blind studies have found that 0.4–0.8 mg/kg body weight per day of glycine can reduce the so-called negative symptoms of schizophrenia when combined with haloperidol and related drugs.9 , 10 Negative symptoms include reduced emotional expression or general activity. The action of glycine in combination with the drugs was greater than the drugs alone, suggesting a synergistic action. Another double-blind study using approximately half the amount in the positive studies could not find any benefit from adding glycine to antipsychotic drug therapy.11 Patients with low blood levels of glycine appeared to improve the most when given glycine in addition to their antipsychotic drugs.12 No side effects were noticed in these studies, even when more than 30 grams of glycine were given daily.
In a small double-blind study, people with schizophrenia being treated with olanzapine experienced an improvement in their symptoms when glycine was added to their treatment regimen.13 The initial amount of glycine used was 4 grams per day; this was increased gradually over a period of 10 to 17 days to a maximum of 0.8 grams per 2.2 pounds of body weight per day.
In a small double-blind study, people with schizophrenia being treated with risperidone experienced an improvement in their symptoms when glycine was added to their treatment regimen.14 The initial amount of glycine used was 4 grams per day; this was increased gradually over a period of 10 to 17 days to a maximum of 0.8 grams per 2.2 pounds of body weight per day.
The use of glycine may interfere with the efficacy of clozapine as an antipsychotic drug. In a double-blind trial, people with chronic, treatment-resistant schizophrenia were given clozapine (400–1,200 mg per day) and either glycine (30 g per day) or placebo for 12 weeks.15 The combination of clozapine and glycine was not effective at decreasing symptoms. In contrast, participants who took clozapine without glycine had a 35% reduction in some symptoms. Therefore, the combination should be avoided until more is known.
Potential Negative Interaction
No clear toxicity has emerged from glycine studies. However, people with kidney or liver disease should not consume high intakes of amino acids without consulting a healthcare professional.
1. Waziri R. Glycine therapy of schizophrenia: Some caveats. Biol Psychiatry 1996;39:155-6.
2. Heresco-Levy U, Javitt DC, Ermilov M, et al. Efficacy of high-dose glycine in the treatment of enduring negative symptoms of schizophrenia. Arch Gen Psychiatry 1999;56:29-36.
3. Evins AE, Fitzgerald SM, Wine L, et al. Placebo-controlled trial of glycine added to clozapine in schizophrenia. Am J Psychiatry 2000;157:826-8.
4. Potkin SG, Jin Y, Bunney BG, et al. Effect of clozapine and adjunctive high-dose glycine in treatment-resistant schizophrenia. Am J Psychiatry 1999;156:145-7.
5. Heresco-Levy U, Javitt DC, Ermilov M, et al. Double-blind, placebo-controlled, crossover trial of glycine adjuvant therapy for treatment-resistant schizophrenia. Br J Psychiatry 1996;169:610-7.
6. Javitt DC, Zylberman I, Zukin SR, et al. Amelioration of negative symptoms in schizophrenia by glycine. Am J Psychiatry 1994;151:1234-6.
7. Semba J. [Glycine therapy of schizophrenia; its rationale and a review of clinical trials]. Nihon Shinkei Seishin Yakurigaku Zasshi 1998;18:71-80 [review] [in Japanese].
8. Rosse RB, Theut SK, Banay-Schwartz M, et al. Glycine adjuvant therapy to conventional neuroleptic treatment in schizophrenia: an open-label, pilot study. Clin Neuropharmacol 1989;12:416-24.
9. Heresco-Levy U, Javitt DC, Ermilov M, et al. Double-blind, placebo-controlled, crossover trial of glycine adjuvant therapy for treatment-resistant schizophrenia. Br J Psychiatry 1996;169:610-7.
10. Javitt DC, Zylberman I, Zukin SR, et al. Amelioration of negative symptoms in schizophrenia by glycine. Am J Psychiatry 1994;151:1234-6.
11. Potkin SG, Costa J, Roy S, et al. Glycine in treatment of schizophrenia—theory and preliminary results. In: Meltzer HY (ed). Novel Antipsychotic Drugs. New York: Raven Press, 1990:179-88.
12. Heresco-Levy U, Javitt DC, Ermilov M, et al. Double-blind, placebo-controlled, crossover trial of glycine adjuvant therapy for treatment-resistant schizophrenia. Br J Psychiatry 1996;169:610-7.
13. Heresco-Levy U, Ermilov M, Lichtenberg P, et al. High-dose glycine added to olanzapine and risperidone for the treatment of schizophrenia. Biol Psychiatry 2004;55:165-71.
14. Heresco-Levy U, Ermilov M, Lichtenberg P, et al. High-dose glycine added to olanzapine and risperidone for the treatment of schizophrenia. Biol Psychiatry 2004;55:165-71.
15. Potkin SG, Jin Y, Bunney BG, et al. Effect of clozapine and adjunctive high-dose glycine in treatment-resistant schizophrenia. Am J Psychiatry 1999;156:145-7.
Last Review: 03-24-2015
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