S-Adenosyl-L-methionine (SAMe) is a naturally-occurring compound found in nearly every tissue and fluid in the body. It is involved in numerous essential processes. SAMe plays a role in the immune system, maintains cell membranes, and helps produce and break down brain chemicals, such as serotonin, melatonin, and dopamine. It works with vitamin B12 and folate (vitamin B9). Being deficient in either vitamin B12 or folate may reduce levels of SAMe in your body.

SAMe is a compound produced by the liver and used throughout the body in a chemical process called methylation. Methylation, essential to numerous chemical reactions in the body, is one of the last steps in the production of the brain chemicals serotonin, dopamine and norepinephrine (which regulate mood).

Some research suggests that SAMe is more effective than placebo in treating mild-to-moderate depression and is simply as effective as antidepressant medications without the side effects (headaches, sleeplessness, and sexual dysfunction). In addition, antidepressants tend to take 6 to 8 weeks to begin working, while SAMe seems to begin more quickly. Researchers are not sure how SAMe works to relieve depression. But they speculate it might increase the amount of serotonin in the brain just as some antidepressants do.

Various studies have examined injectable forms of SAMe, not oral supplements. More research is needed to determine whether SAMe works for depression. Because serious depression is a dangerous illness, you should seek help from your doctor before taking SAMe or any supplement.