Betaine is a natural substance widely distributed in plants and animals such as wheat bran, wheat germ, spinach, sugar beets, microorganisms and aquatic invertebrates. Because it looks like glycine, it has three additional methyl groups, so betaine is also known as trimethylglycine.

Sulfur-containing amino acids such as cysteine, methionine, SAM, SAH and cysteine are involved in a variety of metabolic pathways, including glutathione synthesis and protein synthesis, as well as various methyl transfer reactions. Betaine directly affects the concentration of homocysteine by promoting the formation of methionine from homocysteine, and attenuates the stress response induced by homocysteine. At the same time, betaine converts homocysteine to methionine, which plays an important role in antioxidant action. The transcription factor nuclear factor -κB (NF-κB) pathway controls a number of genes associated with inflammation, including pro-inflammatory cell tumor necrosis factor -α, interleukin 1β, and interleukin 23. Betaine exerts anti-inflammatory effects by inhibiting NF-κB signaling pathway.

Earlier studies have shown that betaine directly increases the expression level of heme oxygenase-1 in hepatocytes, which inhibits NLRP3 inflammasome activation and thus protects the liver from lipopolysaccharide and D-galactosamine-induced inflammation. Recent studies have shown that betaine has a dose-dependent inhibitory effect on NLRP3 inflammasome associated proteins, such as NLRP3 and mature caspase 1, as well as pro-inflammatory cytokines including interleukin 1β, in fructose-induced nonalcoholic fatty liver disease models. It has been reported that high homocysteine can induce misfolded proteins, ultimately leading to er stress response. Betaine can promote the conversion of homocysteine to methionine, maintain cysteine levels, and reduce er stress. In addition to alleviating stress, betaine also inhibits apoptosis.