Betaine, also known as trimethylglycine (TMG), is an organic compound derived from the amino acid glycine in which three hydrogen atoms replace three methyl groups. The name "betaine" comes from the Latin word for beet (Beta), as the substance was first identified in sugar beets.

Betaine occurs naturally in various plants – in addition to beets, it can be found in spinach, cereals and some seafood. The human body can also produce it itself, from choline, which the body receives through food (for example, from eggs or meat).

Within the human body, betaine plays an important role in so-called methylation processes, where it serves as a donor of methyl groups.

These reactions are necessary for the formation and maintenance of various molecules, which is reflected in ensuring the safe operation of multiple biochemical pathways.

Methylation reactions are among the essential processes in the body, as they affect the synthesis of amino acids, the functioning of cellular DNA, as well as a number of other molecules responsible for internal balance.

In addition to its methylation function, betaine is also an osmolyte, meaning it helps cells adapt to changes in water and salt content. In practice, this means that cells are better able to respond to changes in osmotic pressure in the environment, which is especially important in maintaining a stable internal environment in various tissues. Betaine is concentrated to a large extent in the liver and kidneys, where it participates in other metabolic processes that help ensure the proper functioning of these organs.

Trimethylglycine itself is also used in industry, not only in the food industry, but also in cosmetic products. It is popular for its ability to retain moisture and stabilize the structure of some ingredients. In laboratory conditions, it can be part of solutions for research on methylation pathways or for studying osmoprotection of cell cultures.