S-adenosyl-methionine is the most important methyl donor in the body.
It is sometimes referred to as S-Adenosylmethionine or S-Adenosyl-L-Methionine.
In the United States it is sold as a nutritional supplement under the marketing name SAM-e (also spelled SAME or SAMe; pronounced "sam ee"). This means it doesn't have to pass the FDA's tests required of drugs.
Some research[1] has shown that taking SAM-e on a regular basis can help fight depression, liver disease, and the pain of osteoarthritis.