Betaine (trimethylglycine), the trimethylated compound of the amino acid glycine, is an essential biochemical component of the methionine/homocysteine cycle. Betaine acts as a donor of methyl (CH3) groups and, as such, is often used as a nutritional supplement to lower plasma homocysteine levels, and as a lipotropic; i.e., a substance that improves liver function. Betaine also helps maintain intracellular osmolarity and protects proteins from becoming denatured.1 Food sources of betaine include beets, liver, eggs, fish, legumes, and whole grains. Betaine HCl is also commonly used as a nutritional supplement to increase gastric acidity. The betaine in this compound does not alter gastric acidity, but simply “delivers” the hydrochloric acid.