Glycine: benefits, dosage, contraindications
Other name(s)
Aminoacetic Acid
Scientific name(s)
Aminoacetic Acid, L-Glycine
Family or group:
Amino acids
Indications
Scoring methodology
EFSA approval.
Schizophrenia ✪✪✪✪✪
Small clinical trials show that orally administered glycine, in addition to conventional treatment, appears to reduce the negative symptoms of schizophrenia in patients who are resistant to monotherapy with typical antipsychotics such as thioridazine (Mellaril), haloperidol (Haldol), and perphenazine (Trilafon). However, when it is used with the atypical neuroleptic clozapine (Clozaril), glycine appears to have a negligible effect or may worsen schizophrenia symptoms. Furthermore, glycine does not appear to improve the positive symptoms of schizophrenia.nnThus, glycine can reduce neuroleptic-resistant negative symptoms in schizophrenia at a high dose of about 800 mg/kg. nnGlycine 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
Oral
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 with mild sleep deprivation, 3 g of glycine taken one hour before bedtime for 2 to 4 days can improve sleep quality and reduce fatigue, thus contributing to a feeling of well-being the following day.nnGlycine is a co-agonist of the N-methyl-D-aspartate (NMDA) receptor, which means that glycine plays a role in activating this receptor in the brain. The effect of glycine on the NMDA receptor has been proposed to underlie the improvements in sleep and in symptoms of schizophrenia seen with supplementation. Glycine may promote sleep by lowering core body temperature, since an elevated body temperature can impair sleep quality.nn
Posologie
Orally
3 g
4 - days
Metabolic syndrome ✪✪✪✪✪
People with type 2 diabetes have significantly higher levels of urinary glycine excretion and lower serum glycine concentrations than healthy controls. Higher serum glycine concentrations are associated with a reduced risk of developing type 2 diabetes, even after adjustment for lifestyle factors and metabolic syndrome criteria. A study of 12 adults with uncontrolled diabetes reported significantly lower glycine concentrations in red blood cells than in healthy controls (-22%), which were restored by daily supplementation of 100 mg of glycine per kg body weight for 14 days. However, there were no significant effects on fasting blood glucose or HbA1c. Two weeks may have been too short a period to observe glycemic benefits. In contrast, a double-blind randomized controlled trial involving 74 men and women with type 2 diabetes reported that supplementation with 5 g of glycine per meal (15 g/day) for three months resulted in significant reductions in HbA1c compared with placebo (absolute change of -1.4% vs -0.4%), as well as nearly significant reductions in fasting blood glucose (-23% vs -10%).
Posologie
Oral
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 in healthy young adults and in adults with an at-risk mental state for psychosis show that taking glycine at 200–400 mg/kg once or twice daily for periods of up to 24 weeks can improve some measures of memory and cognitive performance compared with baseline or placebo.
Posologie
Orally
10 g
Properties
Neurological
At the level of the central nervous system, glycine acts as an agonist of N-methyl-D-aspartate (NMDA), the glutamate receptor. NMDA receptors are associated with the negative and positive symptoms of schizophrenia and also appear to be associated with memory and learning processes. Furthermore, glycine appears effective at improving sleep quality. Indeed, animal research suggests that this improvement may be due to glycine binding to the same receptor, NMDA, thereby causing vasodilation and a decrease in body temperature. Serotonin release is also increased. Thus, a reduction in sleep disorders such as insomnia is observed. The concentration of glycine in the brain is fairly stable due to dietary intake of glycine. However, supplementation can increase glycine concentrations in the CNS. In addition, some preliminary evidence in animals suggests that glycine could increase daytime expression of arginine vasopressin and vasoactive intestinal polypeptide.
Usages associés
Anti-aging
An in vivo study in 7-week-old rats that received diets composed of a stable dose of methionine and varying doses of glycine demonstrated a improvement in their longevity. The increase in life expectancy was reported to be directly proportional to the ratio between the two amino acids. The authors concluded that glycine supplementation produces biochemical and endocrine changes that induce increased longevity.
Cardiovascular
Glycine can effectively reduce blood homocysteine levels. The latter is the result of methionine metabolism by the liver. While methionine itself is not harmful to health, excessive consumption of it, in combination with an unhealthy lifestyle, increases blood homocysteine levels. Thus, this amino acid is considered dangerous when it reaches high levels. Indeed, according to the latest scientific observations, homocysteine may be responsible for chronic and metabolic diseases, including heart disorders and stroke. In humans with metabolic syndrome, glycine appears to have a beneficial effect on measures of oxidative stress, such as lipid peroxidation. It is possible that protection against oxidative stress could prevent some of the long-term adverse effects associated with metabolic syndrome.
Usages associés
Respiratory effect
In patients with cystic fibrosis, taking glycine modestly improved respiratory function. These improvements were associated with a reduction in granulocyte colony-stimulating factor (G-CSF) levels in sputum, but no changes were observed in 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 burden, and decreases the expression of genes associated with muscle protein degradation in cancer cachexia.
Safe dosage
Adult: 3 g - 5 g
When taken orally and used appropriately, glycine is safe. Up to 9 g have been taken daily for 3 consecutive days.
Interactions
Médicaments
Clozapine: strong interaction
Glycine may worsen symptoms when it is administered with clozapine (Clozaril) in patients with schizophrenia. Although this interaction has not been reported with other atypical antipsychotics, glycine should be used with caution with all atypical antipsychotics.
Precautions
Pregnancy: avoid
Due to lack of reliable information, any glycine supplementation should be avoided. Please consult your doctor.
Breastfeeding: avoid
Due to lack of reliable information, any glycine supplementation should be avoided. Please consult your doctor.
