S-Adenosylmethionine (SAMe) is a key physiological agent formed in the body by combining the essential amino acid methionine to adenosyl-tri-phosphate (ATP). SAMe was discovered in Italy in 1952. Not surprisingly, most of the research on SAMe has been conducted in the country of its discovery.
Because SAMe is manufactured from methionine, one would think that dietary sources of methionine would provide the same benefits as SAMe. However, high doses of methionine have not been shown to increase levels of SAMe, nor does it provide the same pharmacological activity as SAMe, and high dosages of methionine are associated with some degree of toxicity.
Normally the body manufactures all the SAMe it needs from the amino acid methionine. However, a deficiency of methionine, vitamin B12, or folic acid can result in decreased SAMe synthesis. In addition, tissue levels of SAMe are typically low the elderly and in patients suffering from osteoarthritis, depression, and various liver disorders.
Pharmacology
SAMe is involved in over 40 biochemical reactions in the body. It functions closely with folic acid and vitamin B12 in "methylation" reactions. Methylation is the process of adding a single carbon unit (a methyl group) to another molecule. SAMe is many times more effective in transferring methyl groups than other methyl donors. Methylation reactions are critical in the manufacture of many body components especially brain chemicals as well as in detoxification reactions.
SAMe is also required in the manufacture of all sulfur-containing compounds in the human body including glutathione (discussed below) and various sulfur-containing cartilage components.
The beneficial effects of SAMe supplementation are far-reaching due to its central role in so many metabolic processes.
Liver Disorders
SAMe has been shown to be quite beneficial in several liver disorders including cirrhosis, Gilbert's syndrome, and oral contraceptive-induced liver damage. Its benefits are related to its function as the major methyl donor in the liver and it's lipotropic activity. One of the leading contributors to impaired liver function is diminished bile flow or cholestasis. SAMe is beneficial for a variety of liver disorders because of its ability to promote bile flow and relieve cholestasis.
One of the greatest risks of chronic liver diseases such as chronic hepatitis is liver cancer. Supplementation with SAMe appears to be very much indicated in these patients in the attempt to reduce the risk for liver cancer. Animal studies have shown a significant protective effect for supplemental SAMe against liver cancer in animals exposed to liver carcinogens.