Amongst the 22 amino acids vital for our body to function and manufacture proteins, glycine is the smallest and simplest, with only a single hydrogen forming its side chain. Abbreviated at G or Gly, this amino acid has the chemical formula NH2CH2COOH. It’s the second most widespread amino acid found in human enzymes and proteins.
Glycine is biosynthesised in the liver from the amino acids, serine and threonine. As a solid, it’s a sweet tasting crystalline substance and the principle amino acid within cane sugar. In humans, it’s found in high concentrations within the skin, connective tissues and muscle tissues.
Glycine has several important roles within the body. It’s essential for the production of many different acids, including nucleic acids, bile acids, creatine phosphate and porphyrins. On a broader scale, glycine is involved in the regulation and support of many essential processes.
This amino acid is closely associated with the central nervous system and the digestive system. Glycine helps with the breakdown of fat by regulating the concentration of bile acids. Glycine is also required for the biosynthesis of heme. Heme is a key component of haemoglobin. Haemoglobin is essential in the maintenance of red blood cell integrity and optimal oxygen carrying capacity.
Due to the range of functions performed by glycine, this amino acid has proven to be important in the treatment of a variety of medical conditions, as well as supporting overall well-being. Some of the benefits of glycine are outlined below.
Within the central nervous system glycine works together with taurine and gamma-amino butyric acid (GABA) as an inhibitory neurotransmitter.
It functions principally within the brain stem and spinal cord where it facilitates the transmission of nerve impulses. Glycine interferes with the hyper-excitability of the central nervous system neurons by removing chloride and potassium to regulate their ability to be over stimulated.
There have been numerous studies investigating the benefits of this amino acid in the treatment of disorders such as hyperactivity, schizophrenia, bipolar, and epilepsy. One study focusing on treatment-resistant schizophrenic patients found that high-dose glycine in association with antipsychotic medication could significantly alleviate negative symptoms associated with this mental illness1. These results are supported by similar studies investigating psychological disorders2 3. Other studies have shown that glycine treatments can help to prevent seizures associated with epilepsy 4 5.
Glycine assists with the regulation of blood sugars by converting glucose into energy. There is evidence to support the use of glycine to improve the long-term blood sugar levels within individuals suffering from type 2 diabetes 6 7. As glycine is sweet, it’s often recommend as a sugar supplement for diabetics.
Glycine is one of the amino acids necessary for the biosynthesis of creatine. Creatine provides muscles with a direct energy source and helps to build muscle tissue and strength. Thus, glycine is an important amino acid for athletes wanting to increase muscle mass and performance.
It’s also helpful for patients recovering from surgery or other causes of immobility because it can help to prevent muscle degeneration.
Glycine is an important anti-aging amino acid. Approximately one third of collagen is comprised of glycine. Collagen is the essential protein required to keep the connective tissue and skin flexible and firm. In the absence of glycine, damaged tissues can’t be repaired. Research has shown that glycine helps to protect the body against shock as a result of blood loss; it also helps to prevent free radical formation and hypoxia8.
This amino acid can be methylated into dimethylglycine (DMG). DMG plays an important role in the one-carbon pathway that’s essential for the biosynthesis of steroids such as estrogenic and androgenic hormones. Glycine also helps to stimulate the secretion of human growth hormone.
Preliminary studies have shown that glycine may have a role to play in the treatment of certain cancers, including the prevention of formation of cancerous melanoma and tumours. Results from a study on mice found that dietary glycine inhibited angiogenesis, stopping the growth of tumours 9.
Glycine deficiencies are uncommon. However, they can occur in individuals that are malnourished or have diseases such as cancer and AIDS. Individuals that have digestive disorders or suffer from fatigue or low energy levels may also have inadequate glycine concentrations.
Although the body can manufacture glycine, this amino acid can also be sourced from many high-protein foods. In particular, fish, meat and dairy are rich sources of glycine. Vegetarian glycine sources include soybeans, spinach, kale, cauliflower, cabbage, pumpkin, banana, kiwi fruit, cucumber and beans.
There are also supplements available in the form of powders or capsules that are often used to treat medical conditions such as prostrate problems, poor memory, stroke and schizophrenia. Other supplements containing glycine are available to help treat chronic fatigue syndrome, anaemia and hypoglycaemia. Theses supplements are designed to boost energy levels and general well-being.
Often you’ll come across glycine within food and beverage products as a taste enhancer and sweetener. It’s also used as an additive in animal feed, a buffering agent in cosmetics, antacids, irrigation solutions and in agricultural fertilizers. Many commercial applications use a synthetic version of glycine produced by using ammonia to treat chloroacetic acid.
Given that glycine is one of the most common amino acids found within human proteins, it’s not surprising that this simple compound has so many functions with the body. Glycine is particularly important in maintaining healthy digestive and central nervous systems.
It’s role in the production of human growth hormones and creatine have also seen glycine become a valuable amino acid for athletes wanting to build muscle mass and strength.
Glycine also has positive applications for individuals suffering from neurobehavioral disorders, diabetes, chronic fatigue and certain cancers. As more research and clinical trials are conducted, it’s likely that this amino acid will continue to play an important role in the treatment of a range of medical conditions.
Maintaining a healthy diet including glycine-rich foods will help to support the body and supplement internal glycine biosynthesis.
- “http://www.ncbi.nlm.nih.gov/pubmed/9892253” ↩
- “http://www.ncbi.nlm.nih.gov/pubmed/9272487” ↩
- “http://www.ncbi.nlm.nih.gov/pubmed/8932891” ↩
- “http://www.ncbi.nlm.nih.gov/pubmed/17041593” ↩
- “http://www.ncbi.nlm.nih.gov/pubmed/9708551” ↩
- “http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2696340” ↩
- “http://care.diabetesjournals.org/content/34/1/162.full” ↩
- “http://www.ncbi.nlm.nih.gov/pubmed/11939124” ↩
- “http://www.ncbi.nlm.nih.gov/pubmed/10334195” ↩