Glycine can be formed from choline in the liver or kidney and from the amino acids threonine and serine. It can be converted back to serine in the fasting state. Glycine is one of the few amino acids that helps spare glucose for energy by improving glycogen storage. It is important in brain metabolism, where it has a calming effect. Glycine is a simple amino acid needed for the synthesis of the hemoglobin molecule, collagen, and glutathione. It can also be converted to cre-atine, which is utilized to make DNA and RNA. Glycine is useful in healing wounds (orally or in a cream) and treating manic psychological states or problems of muscle spasticity. When the blood fats or uric acid levels are high, it helps to clear or utilize these substances. Glycine may also be helpful in reducing gastric acidity; in higher doses, 4–8 grams, it stimulates growth hormone release; and it is also used as a mild sweetener in foods or drugs.
Dimethylglycine (DMG) is a popular substance in today's nutritional products. It will also be discussed as a corollary for vitamin B15, pangamic acid. DMG is an intermediary of cell metabolism, mainly from glycine and choline. As a precursor also to glycine, some of DMG's effects may be attributed to simple glycine, particularly in regard to its neuroinhibitory effect in problems such as epilepsy. DMG seems to be able to increase the immune antibody response and improve physical energy and has been used in the treatment of infections, immune suppression, fatigue, and poor endurance. Some people experience good results; others do not. More research is needed to properly understand dimethylglycine's role in clinical medicine.