Glycine is a nonessential amino acid. This means that glycine can be synthesized in the human body, as sources for that are the amino acids serine and threonine. Glycine is present in both animal and plant sources. Because its main concentrations are in the soft tissues, animal sources are far richer in concentration.
The richest source of glycine is the gelatin protein and all sources of gelatin - cartilage, skin, and other soft tissues. The main biological role of glycine is for the formation of proteins.
The more important role of glycine is for the central nervous system. It functions as an inhibiting neurotransmitter mainly in the spinal cord, retina and brain cells. As a neurotransmitter glycine interacts with taurine and GABA.
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What Is Glycine
Glycine is a nonessential amino acid. This means that glycine can be synthesized in the human body, as sources for that are the amino acids serine and threonine.The synthesis of glycine is performed through enzymatic reactions, as pyridoxal-5-phosphate is a cofactor. Glycine is the smallest amino acid.
It has the simplest structures of all amino acids and it contains only one molecule of hydrogen, which forms its side chain. Glycine is an amino acid that is abundant in the human body.
It is the second most common amino acid in proteins and enzymes after glutamine. The structure of glycine is crystalloid, the taste is sweet. It is not a surprise that glycine is one of the basic building blocks of the sugar cane. In the human body, glycine is most concentrated in the skin, connective tissues, and muscles.
What Are the Main Sources of Glycine
Glycine is present in both animal and plant sources. Because its main concentrations are in the soft tissues, animal sources are far richer in concentration. The richest source of glycine is the gelatin protein and all sources of gelatin - cartilage, skin, and other soft tissues.
The concentration of glycine in gelatin reaches 11 grams per 100 grams. Pork, beef, ostrich meat and crabs have a high content of glycine. Among the plant sources spinach, wetting, and horseradish are richest in glycine.
High concentrations of glycine are contained also in the green algae spirulina (2100-2400 mg per 100 g).
How Does Glycine Work
The main biological role of glycine is for the formation of proteins. It is a key product for the synthesis of collagen and it interacts with hydroxyproline.
Glycine is involved in the construction of some acids like nucleic acid, bile, and creatine phosphate. In the human body, glycine is related to digestion and the nervous system function.
Glycine helps break down fats because it stimulates the secretion of bile, but it is believed that this function is not so strong in a healthy digestive tract. The more important role of glycine is for the central nervous system.
It functions as an inhibiting neurotransmitter mainly in the spinal cord, retina and brain cells. As a neurotransmitter glycine interacts with taurine and GABA. It inhibits the agitation and it voids of the excess chloride and potassium. Glycine is a natural co-agonist of the excitatory neurotransmitters glutamate and NMDA (N-methyl-D-aspartate).
The glycine receptor is activated not only from glycine but also from other amino acids such as taurine and beta-alanine. The receptor may be partly blocked by its rival antagonist strychnine. Recently it has been found that caffeine acts on the glycine receptor as a rival antagonist.
It has been found that the malfunctioning of the glycine receptor can reduce the binding of the chloride ions and this could lead to the rare neurological disease hyperekplexia. This disease is expressed in a disruption of the muscle function during unexpected and sharp excitation that leads to uncontrolled falling.
Proven and Potential Benefits for Humans
- It is claimed that glycine helps lower cortisol. The famous power trainer Charles Poliquin recommends a combination of glycine and phosphatidylserine. Despite the promising results more research is needed to categorically confirm the properties of glycine;
- Several studies have demonstrated that glycine enhances the quality of sleep. In one of them, volunteers have been subjected to physical training and 25% less sleep. The results have indicated a sharp reduction of the fatigue and need for sleep during the day. The positive effect is due to the effects of glycine on certain neuropeptides;
- Glycine eliminates the excess potassium and chlorine from the nervous system. It prevents them from being used for overstimulation;
- The intake of glycine helps reduce the symptoms of schizophrenia. It is interesting to note that glycine contributes per se and enhances the effect of antipsychotics drugs;
- Potential benefits in suppressing the hyperactivity at some psychological diseases;
- The intake of 200 mg/kg BW of glycine (16 g to 80 kg man) dramatically improves the condition of epilepsy. Complete disappearance of relapses after 6 months of dosing has been noted;
- Glycine lowers the blood sugar and stimulates the use of glucose for energy. Several studies have indicated that glycine influences positively the blood glucose levels over a long-term use in type 2 diabetes. Glycine is often recommended as a sugar substitute because it has a sweet taste and is completely safe for diabetics;
- In sporting terms it helps decrease fatigue and increase endurance because of its positive effect on the glucose metabolism and synthesis of creatine phosphate;
- A Spanish study has shown that glycine has strong antioxidant and anti-inflammatory properties and it drastically inhibits the inflammatory cytokines;
- Glycine builds the collagen protein and is believed to have potential benefits for the synthesis of the collagen tissues, anti-aging effect, and recovery of the affected tendons and cartilage;
- It has strong detoxifying properties. It has been found that glycine regulates the alcohol levels in the stomach and helps for the treatment of alcoholic hepatitis, reduces the neurotoxicity from the use of drugs, and prevents the formation of free radicals in the kidneys;
- The use of glycine has the potential for the normalization of the body in case of shock, caused by severe blood loss or invasion of endotoxins;
- Glycine is a powerful precursor of the antioxidant glutathione;
- Glycine strengthens the effect of acetylsalicylic acid and reduces its negative effects on the stomach;
- Protects from neurological disability in case of stroke, reducing the risk of negative consequences to 66%.
Side Effects and Contraindications
Glycine is considered a safe amino acid, even in extremely high doses. However, there are no more detailed studies that monitor its impact on the body with high doses over the long term.
Due to the lack of sufficient scientific basis, the intake of high doses of glycine (10+ grams) during pregnancy, lactation, and problems with the kidneys or liver is not recommended.
It is possible for high doses to irritate the stomach or to cause mild nausea or laxative effect. These symptoms are rare and occur at a high single dose. The intake of glycine with the antipsychotic drug clozapine. Persons who have suffered a heart attack can take glycine only under the supervision of a physician.
How to Combine Glycine
Glycine can be used both for sports and health purposes. If the target is the pre-workout intake for the improvement of the stamina during a workout, the combination with L-carnitine, taurine, and creatine is recommended.
Coach Charles Poliquin recommends glycine as a means of reducing the stress hormone cortisol. According to the proposed scheme, the most effective way to regulate cortisol is the combination of glycine and phosphatidylserine.
According to the various objectives, glycine could be used in different doses. If glycine is included in a pre-workout stack, the dose of 5 grams before a workout would have a positive effect on the sports performance.
As a means of improving sleep, the doses are 5 to 10 g, 30 minutes before sleep. A shock dose before bedtime can be counterproductive and act as a tonic.
For the lowering of cortisol Poliquin recommends the intake of 10 grams before bedtime or after training. For the treatment of severe mental illness, doctors use 60 grams of glycine per day, with no side effects.
In Which Supplements Can We Find Glycine
Glycine is available as a separate nutritional supplement. Some brands offer it as a powder. The crystalloid form, sweet taste, and its easy solubility make glycine easy to consume.
Glycine is also available in the form of capsules, but only in a liquid form. Liquid dragees are easier to swallow. Glycine can be found in some complex formulas.
Many manufacturers add it to pre-workout products because of the potential benefits of glycine to increase stamina and control fatigue. Others use glycine in post-workout formulas for recovery.
Glycine is very rarely added to products that improve the quality of sleep and calm the nervous system. Despite its small popularity, glycine is an amino acid that has a lot to offer - both from a health perspective and in sports.
Glycine may be the smallest and simplest amino acid, but it surprises us with many positive features that could prove to be crucial to our health. Although not advertised and actively offered, glycine is a relatively cheap supplement and does not strain the budget. These qualities make it a favorite supplement for many users.