Methionine is an essential amino acid—one of the building blocks of proteins and peptides that your body cannot manufacture from other chemicals. The body uses methionine to manufacture creatine and uses the sulfur in methionine for normal metabolism and growth.

One preliminary study suggests that methionine can prevent bacteria from sticking to urinary tract cells,1 which may make it useful for preventing bladder infections. ( Cranberry juice is thought to help reduce the incidence of bladder infections in a similar fashion.)

Depending on your body weight, you need between 800 and 1,000 mg of methionine daily for normal health. Deficiency is unlikely because enough methionine is generally available from the diet.

Meat, fish, dairy products, and other high-protein foods are good sources of methionine.