Research studies over the past five decades have established the importance of SAMe in the cellular metabolism and function of all living organisms. The diet cannot provide adequate quantities of SAMe; therefore, the body relies on de novo synthesis to sustain the required concentrations of this essential metabolite. Pharmaceutical preparations of SAMe are available mainly in Europe as intravenous, intramuscular, and oral forms. An over-the-counter nutraceutical oral form is available in the United States.
Studies have shown that SAMe, when given in high pharmacologic doses, is absorbed and is utilized by being incorporated into the endogenous cellular pathways inherent in all cells. In health conditions, where SAMe concentrations are reduced (either as a result of genetic defects, drug effects, or health disorder), there is a rational basis for using SAMe to restore methyl-group metabolism. A sufficient number of clinical trials have supported the therapeutic use of SAMe in disorders including depression, dementia, vacuolar myelopathy, and liver conditions. Though there have been much clinical efforts in SAMe, further studies should be performed to better understand the safety and tolerability of SAMe. Reviews of clinical studies to date indicate that SAMe has a low incidence of side effects with an excellent record of tolerability. This is of significant clinical benefit, particular in the elderly, in whom conventional therapies are often not tolerated well.
Although a considerable amount of literature exists on the biochemical and molecular roles of SAMe in cellular metabolism, further studies are needed to better understand its pharmacologic action. Clinical studies have shown clearly that SAMe has considerable potential in the therapeutic support of depression, other neurologic disorders, and liver health. Further studies should explore the full clinical potential of SAMe, and a primary objective should be defining the optimal dosage. Adequate dose-escalation studies have not been performed for use of SAMe in depression, liver health, or osteoarthritis, especially with the newer oral formulations of SAMe. This information is needed before additional large clinical trials can be designed. The lack of any significant side effects may allow the long-term use of SAMe for evaluation of any possible prophylactic effect.