S-adenosyl-l-methionine (SAMe) for smoking abstinence: A randomized clinical trial

Objectives: S-Adenosyl-l-methionine (SAMe) is a dietary supplement commonly used to treat depression. SAMe facilitates dopamine and norepinephrine synthesis in the central nervous system. This study investigated the efficacy of SAMe for increasing tobacco abstinence among cigarette smokers. Design: A randomized, blinded, placebo-controlled, three-arm, dose-ranging clinical trial was conducted. Subjects were randomly allocated to receive SAMe 1600 mg or 800 mg by mouth every day or a matching placebo for 8 weeks. All subjects received a behavioral smoking cessation intervention. Self-reported smoking abstinence was biochemically confirmed with exhaled-air carbon monoxide. Subjects: Subjects in the study comprised 120 adults. Results: One hundred and twenty (120) subjects with a mean age of 40.0±14.0 (SD) years were enrolled. Participants smoked an average of 19.6±8.6 cigarettes per day for 21±13.2 years. The study dropout rate was high (42.5%). By intention-to-treat analysis, no significant differences were observed in abstinence rates at 8 and 24 weeks between SAMe dose groups and placebo. SAMe did not attenuate withdrawal symptoms among abstinent subjects. Rates of gastrointestinal side-effects were higher with SAMe 1600 mg/d compared to placebo. Conclusions: SAMe did not increase smoking abstinence rates. Abstinence and tobacco withdrawal data from this clinical trial suggest that SAMe holds little promise for the treatment of tobacco dependence.