L-methionine is used for protein synthesis including the formation of SAMe, L-homocysteine, L-cysteine, taurine, and sulfate. The addition of methionine to the diet induces the body to manufacture keratin. Keratin is the main material of the hair shaft, one of the essential proteins for its appearance. Methionine also helps smooth hair and add shine. It is also used as an active ingredient for intravenous nutrical products as a source of calories, protein and electrolytes for patients requiring parenteral nutrition when oral or enteral nutrition is not possible, insufficient or contraindicated.