Hemodynamic and Electrocardiographic Effects of “Ephedra‐free” Dietary Supplements

Abstract

An investigation into the effects of 4 popular “Ephedra-free” dietary supplements (Metabolift, Zantrex 3, Xenadrine EFX, Guarana) on heart rate, blood pressure, and electrocardiographic parameters was conducted. 12 healthy males (age 31± 7.8 years) volunteered to participate. All subjects were non-smokers, took no medications, and refrained from caffeine intake and physical exertion throughout the study. The study was randomized for supplementation sequence with a 2-week washout period between each phase. Subjects wore a Holter monitor for 24 hours on day 1 of each phase (baseline) for assessment of electrocardiographic activity. Blood pressure and heart rate were also assessed at each baseline. Subjects ingested supplements 3 times daily for 3 consecutive days. On days 1 and 3 of supplementation, Holter monitors were again placed and hemodynamic parameters evaluated. On day 1, systolic (SBP) and diastolic (DBP) blood pressures were significantly increased relative to baseline (9.8 ± 2.2 and 5.8 ± 1.7 mm Hg, respectively). By day 3, these effects were somewhat attenuated (5.1 ± 1.6 mm Hg, SBP; 3.0 ± 2.0 mm Hg, DBP). Abnormal atrial and ventricular events were noted in several subjects during supplementation. Our findings suggest that “Ephedra-free” dietary supplements may not be free of adverse cardiovascular effects and their use should be discouraged in consumers with underlying cardiovascular disease.