Glycine: Effects, Uses & Risks

Glycine is the simplest alpha-amino acid and thus a component of all proteins. Glycine is particularly present in high concentrations in connective tissue. In the body, it serves as a central switch point between protein, carbohydrate and fat metabolism.

What is glycine?

Glycine is used as an important ingredient in certain drugs and as a dietary supplement. Glycine is a nonessential, proteinogenic amino acid with no side chains or functional groups and is universally found in all proteins. Quite mundanely, the molecule contains an amino group in alpha position to the carboxy group in addition to the two carbon atoms. Thus, the molecule fulfills the basic requirement for an amino acid. Glycine plays a central role in biometabolism, since it repeatedly appears as an intermediate in chemical conversions. It is also hygroscopic (attracts water) because its dipole character allows it to bind water molecules to itself via hydrogen bonds. Furthermore, the glycine molecule is very small and thus does not require much space. Therefore, it is incorporated in high concentrations into proteins, which must be very stable but also take up little space. In these proteins, the peptide chains must be very long and at the same time strongly folded. The structural proteins of connective tissue, the collagens, fulfill precisely these requirements.

Pharmacological action

Glycine has multiple functions to perform in the body. First, it is incorporated into all proteins as an alpha-amino acid. Mainly in the protein of connective tissue, it is present up to 30 percent. Glycine is thus the most important basic building block for the formation of bones, tendons, teeth and skin. Glycine is a non-essential amino acid. The human body can produce it itself from other compounds. However, if it is not sufficiently supplied with food due to malnutrition, the connective tissue serves as a source of glycine. Glycine is the starting compound for the biosynthesis of purines, the basic building blocks of genetic material. It is also used for the synthesis of heme, the iron-containing protein of red blood cells. Glycine can also be used to form creatine, which is responsible for muscle growth. Glycine is also an essential component of the important radical scavenger glutathione. Glycine also fulfills other functions in fat metabolism, as it is involved in the formation of bile acids. The bile acids control fat digestion. In the central nervous system, glycine functions as an inhibitory neurotransmitter. It causes muscle activity to be inhibited.

Medical application and use

Glycine exerts a variety of beneficial effects on the body. It is used as an important ingredient in certain medicines and as a dietary supplement. Glycine is known as the flavor enhancer E 640 in sweetener tablets, as it has a sweetish taste. Furthermore, it is found as an additive in certain dietary products for flavor enhancement. As an ingredient in medicines, it helps the body detoxify. It also strengthens the immune system and acts against inflammation. These effects are mediated by glycine through the formation of glutathione, as glutathione can scavenge free radicals. Furthermore, glycine inhibits intestinal activity and can be used in cases of severe illness and surgery in the gastrointestinal tract. In these cases, it is often introduced intravenously in the form of artificial nutrition, thus sparing the digestive organs. Glycine is also often used in medicines together with arginine as a therapeutic agent in cases of arteriosclerosis, osteoporosis and arthrosis. Glycine also promotes the release of glycogen from the liver. In this way, it has a regulating effect on blood sugar levels during hypoglycemia. Glycine has been found to be effective in sleep disorders and panic attacks.

Risks and side effects

Side effects of glycine have not been found so far. It can therefore not be overdosed, since glycine supplied to the body is quickly converted in the metabolism. Due to this fact, there are also no limit values. However, a deficiency of glycine can have dramatic effects in the worst case. For example, in the case of poisoning with strychnine or special infections such as tetanus, glycine is bound so that it can no longer perform its function as an inhibitory neurotransmitter. This results in severe muscle spasms, which can be fatal due to the impairment of the respiratory organs.If a reduced dietary intake of glycine leads to a glycine deficiency, more connective tissue is broken down, often causing fatigue.