the constituent of hemoglobin, tissue and serum with the function of promotion of the spleen, pancreas and lymph. Methionine is a sulfur-containing essential amino acid, closely related to the in-vivo metabolism of a variety of sulfur compounds. The lack of methionine will cause loss of appetite, growth-slowing or stagnation of weight-gaining, enlarged kidney and liver iron accumulation etc, then lead to liver necrosis or fibrosis. Methionine can also methylate the toxics or drugs with its methyl to perform the function of detoxification. Thus, methionine can be used in the prevention and treatment of liver diseases such as chronic or acute hepatitis and cirrhosis, etc, and in the alleviation of the toxicity of harmful substances such as arsenic, chloroform, carbon tetrachloride, benzene, pyridine and quinoline and so on.