Abstract
Background Cardiovascular stimulant effects have been described with use of dietary supplements (DS) containing ephedra and caffeine (E/C) that are used for weight loss and athletic performance enhancement. Metabolic effects of these DS have not been described, but may contribute to cardiovascular toxicity. Methods 16 healthy adults (8 women) took 2 doses each of E/C alone, a multi-component DS containing 25 mg ephedra alkaloids and 200 mg caffeine, or placebo 6 hours apart in a 3-arm placebo-controlled, crossover study. Blood chemistry values were measured on samples collected for 10 hours after dosing. Results Post-prandial glucose and insulin were maximally increased 2 hours after eating, producing a 1.7-fold rise in insulin resistance (p=0.003). Peak values were glucose: 118.2 ± 17.8 mg/dl for DS vs. 91.2 ± 15.3 mg/dl for placebo, (p=0.001); and insulin: 82.2 ± 43.6 μU/ml for E/C vs. 42.9 ± 24.7 μU/ml for placebo, p=0.01). Serum potassium was decreased for 3 hours after dosing (3.60 ± 0.17 mmol/L for DS vs. 3.94 ± 0.29 mmol/L for placebo, p<0.0001). 15/16 subjects became hypokalemic (K+ <3.5 mmol/L) after E/C treatment. Conclusions Insulin resistance and hypokalemia were observed in healthy adults taking usual doses of E/C found in DS. If persistent, such effects could increase risk of dyslipidemia, Type 2 diabetes, and cardiovascular disease, and, in the setting of E/C-induced cardiac stimulation, hypokalemia could predispose to development of cardiac arrhythmias. Clinical Pharmacology & Therapeutics (2004) 75, P44–P44; doi: 10.1016/j.clpt.2003.11.165
Published Version
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