Glycine: benefits, dosage, contraindications
Other name(s)
Aminoacetic Acid
Scientific name(s)
Aminoacetic Acid, L-Glycine
Family or group:
Amino acids
Indications
Rating methodology
EFSA approval.
Schizophrenia ✪✪✪✪✪
Small clinical trials show that oral glycine, in addition to conventional treatment, seems to reduce the negative symptoms of schizophrenia in patients who are resistant to monotherapy with classic antipsychotics such as thioridazine (Mellaril), haloperidol (Haldol), and perphenazine (Trilafon). However, when used with the atypical neuroleptic agent clozapine (Clozaril), glycine appears to have negligible effects or worsen schizophrenia symptoms. Furthermore, glycine does not seem to improve the positive symptoms of schizophrenia. Thus, glycine is capable of diminishing neuroleptic-resistant negative symptoms in schizophrenia at a high dose of about 800 mg/kg. Glycine has also been used at doses ranging from 400 to 800 mg/kg per day in divided doses. In one study, the initial dose was 200 mg/kg, then doubled each week to a final dose of 600 mg/kg.
Posologie
Orally
200 - 800 mg/kg
Amelioration of negative symptoms in schizophrenia by glycine.
Amelioration of negative symptoms in schizophrenia by glycine.
Efficacy of high-dose glycine in the treatment of enduring negative symptoms of schizophrenia.
The effects of glycine on auditory mismatch negativity in schizophrenia.
Double-blind, placebo-controlled, crossover trial of glycine adjuvant therapy for treatment-resistant schizophrenia.
The effects of glycine on auditory mismatch negativity in schizophrenia.
Double-blind, placebo-controlled, crossover trial of glycine adjuvant therapy for treatment-resistant schizophrenia.
Sleep disorders ✪✪✪✪✪
In individuals experiencing mild sleep deprivation, 3 g of glycine one hour before bedtime for 2 to 4 days can improve sleep quality and reduce fatigue, contributing to a sense of well-being the following day. Glycine is a co-agonist of the N-methyl-D-aspartate (NMDA) receptor, meaning glycine plays a role in the activation of this receptor in the brain. The effect of glycine on the NMDA receptor has been proposed as the reason for sleep improvements and schizophrenia symptom improvements during supplementation. Glycine may promote sleep by lowering the central body temperature, as a high body temperature can impair sleep quality.
Posologie
Orally
3 g
4 - days
Metabolic syndrome ✪✪✪✪✪
Individuals with type II diabetes exhibit significantly higher glycine urinary excretion levels and lower serum glycine concentrations than healthy controls. Higher serum glycine concentrations are associated with a reduced risk of developing type II diabetes, even after adjusting for lifestyle factors and metabolic syndrome criteria. A study involving 12 adults with uncontrolled diabetes reported significantly lower glycine concentrations in red blood cells than healthy controls (-22%), which were restored by a daily supplementation of 100 mg of glycine per kg of body weight for 14 days. However, there were no significant effects on fasting blood glucose or HbA1c. It's possible that two weeks was too short a period to observe glycaemic benefits. Conversely, a double-blind randomized controlled trial involving 74 men and women with type II diabetes reported that supplementation with 5 g of glycine per meal (15 g/day) for three months resulted in significant reductions in HbA1c compared to placebo (absolute change of -1.4% vs. -0.4%), along with near-significant reductions in fasting blood glucose (-23% vs. -10%).
Posologie
Orally
5 g
5 - days
Novel biomarkers for pre-diabetes identified by metabolomics
Oral supplementation with glycine reduces oxidative stress in patients with metabolic syndrome, improving their systolic blood pressure
Homocysteine and cardiovascular disease: evidence on causality from a meta-analysis.
Glycine treatment decreases proinflammatory cytokines and increases interferon-gamma in patients with type 2 diabetes
Assessing the causal association of glycine with risk of cardio-metabolic diseases
Glutathione synthesis is diminished in patients with uncontrolled diabetes and restored by dietary supplementation with cysteine and glycine
Metabolomics study of type 2 diabetes using ultra-performance LC-ESI/quadrupole-TOF high-definition MS coupled with pattern recognition methods
Plasma Amino Acids vs Conventional Predictors of Insulin Resistance Measured by the Hyperinsulinemic Clamp
Neuroprotective effects of glycine for therapy of acute ischaemic stroke.
Cognitive performance ✪✪✪✪✪
Two small clinical studies conducted on healthy young adults and adults with a risk syndrome for psychosis show that taking glycine at a dosage of 200-400 mg/kg once or twice a day for a period of up to 24 weeks can improve certain measures of memory and cognitive performance compared to baseline values or placebo.
Posologie
Oral route
10 g
Properties
Neurological
At the central nervous system level, glycine acts as an agonist of the N-methyl-D-aspartate (NMDA) glutamate receptor. NMDA receptors are associated with both negative and positive symptoms of schizophrenia and seem to also be associated with memory and learning processes. Moreover, glycine appears effective in improving sleep quality. Indeed, animal studies suggest that this improvement may be due to glycine binding to the same receptor, NMDA, thereby causing vasodilation and lowering body temperature. Serotonin release is also increased. Thus, there is a reduction in sleep disorders such as insomnia. The concentration of glycine in the brain is quite stable due to dietary glycine intake. However, the addition of supplements can increase glycine concentrations in the CNS. Moreover, some preliminary animal evidence suggests that glycine could increase the diurnal expression of arginine vasopressin and vasoactive intestinal peptide.
Usages associés
Anti-aging
An in vivo study on rats aged 7 weeks who received meals consisting of a stable dose of methionine and various doses of glycine demonstrated an improvement in their longevity. The increase in lifespan appeared directly proportional to the ratio between the two amino acids. The authors concluded that glycine supplementation led to biochemical and endocrine changes inducing increased longevity.
Cardiovascular
Glycine can effectively reduce blood homocysteine levels. The latter is the result of methionine metabolization by the liver. While methionine in itself is not detrimental to health, its excessive consumption, coupled with an unhealthy lifestyle, raises blood homocysteine levels. Thus, this amino acid is considered dangerous when it reaches high levels. In fact, according to recent scientific observations, homocysteine may be responsible for chronic and metabolic diseases including heart disorders and stroke. In humans with metabolic syndrome, glycine seems to have a beneficial effect on oxidative stress measures, such as lipid peroxidation. It is possible that protection against oxidative stress could prevent some long-term adverse effects associated with metabolic syndrome.
Usages associés
Respiratory effect
In patients with cystic fibrosis, glycine intake modestly improved respiratory function. These improvements were associated with lower levels of granulocyte colony-stimulating factor (G-CSF) in the sputum, but no change was observed in the sputum or serum levels of any other inflammatory marker.
Musculoskeletal effects
Glycine protects skeletal muscles from atrophy and loss of function, reduces oxidative and inflammatory loads, and decreases the expression of genes associated with muscle protein degradation in cancer cachexia.
Safety dosage
Adult: 3 g - 5 g
Orally, if glycine is taken appropriately, it is safe for health. Up to 9 g have been taken daily for 3 consecutive days.
Interactions
Médicaments
Clozapine: strong interaction
Glycine may worsen symptoms when administered with clozapine (Clozaril) in schizophrenic patients. Although this interaction has not been reported with other atypical antipsychotics, glycine should be used cautiously with all atypical antipsychotics.
Precautions
Pregnant woman: avoid
due to a lack of reliable information, any glycine supplementation should be avoided. Please consult your doctor.
Breastfeeding woman: avoid
due to a lack of reliable information, any glycine supplementation should be avoided. Please consult your doctor.
