Betaine is distributed widely in animals, plants, and microorganisms and rich dietary sources include seafood, especially marine invertebrates. Betaine is N-trimethylated amino acid called as glycine betaine. It is a by-product. Betaine aldehyde is produced when choline dehydrogenase acts on choline, then betaine aldehyde is oxidized to form betaine by aldehyde dehydrogenase. Metabolic derived betaines possess various functions in our body in which they act as methyl donor which helps in liver function, detoxication, and cellular functions. It plays an important role in fat metabolism. Recent research found that betaine can convert homocysteine to cysteine thus they prevent heart disease. Choline is oxidized to betaine in liver and kidney. Intracellular betaine serves as an osmolyte that regulates cell volume and tissue integrity. Betaine not only plays as an osmolyte but also play a major role in the protection of the liver and other tissues. Consequently, it has been proposed that betaine has significant nutrient for prevention of chronic disease. Betaine has been shown to protect internal organs, improve vascular risk factors, and enhance performance. Databases of betaine content in food are being developed for correlation with population health studies. This review focuses on the aspects of wide research field with emphasis on a recent data relevant to various human diseases
