" S-adenosyl-methionine (SAMe) is a natural derivative of an amino acid normally produced by the body, and it plays a role in methylation (see Chapter 5). Levels of SAMe in the body often become depleted by middle age.
Multiple clinical trials have shown that SAMe provides substantial benefit for patients with depression. This effect occurs relatively quickly, unlike the requirement to build up levels in the bloodstream that accompanies some prescription drugs for depression. It is, therefore, an effective, natural, and quick-acting treatment for mild depression. Human trials have also shown benefits for strengthening the liver and for relief from osteoarthritis. "

― Ray Kurzweil , Transcend: Nine Steps to Living Well Forever