Cardiovascular toxicity associated with supplement use.

BACKGROUND: Supplement use is prevalent and appears to be increasing over time. In the United States, regulation by the Food and Drug Administration is limited largely to post-marketing surveillance, raising safety concerns. A variety of supplements have been associated with cardiovascular toxicity, which can occur via adulteration, substitution, or as a result of intrinsic toxicity of the supplement. Cardiovascular toxicity due to supplement use may arise via several different mechanisms, and has been reported with supplements that act as central nervous system stimulants, via poisoning of cardiac ion channels, as a result of cardioactive steroids, and by modulation of the endocrine system.

STIMULANTS: Supplements that act as central nervous system stimulants include those that act directly on adrenoreceptors or indirectly via the release of catecholamines, and include substances such as ephedra, synephrine, and yohimbine. Adverse effects vary depending on the agent and include tachycardia, hypertension, hyperthermia, myocardial infarction, and cardiac arrest.

ION CHANNEL POISONS: Poisoning of cardiac voltage-gated sodium channels has been reported with supplements that contain or are contaminated with aconitine or grayanotoxins and cause wide complex dysrhythmias. Inhibition of cardiac myocyte voltage-gated potassium channels is associated with berberine, leading to prolongation of the QT interval and polymorphic ventricular tachycardia.

CARDIOACTIVE STEROIDS: Cardioactive steroids derived from yellow oleander are implicated in serious toxicity and death associated with the weight loss product "Nuez de la India" in what appears to be an inadvertent substitution error. Animal-derived cardioactive steroids from the Bufo spp. of toad used as an aphrodisiac also cause clinically significant cardiac toxicity and death.

ENDOCRINE MODULATORS: Supplemental use of black licorice induces hypokalemia, and is associated with the development of torsade de pointes.

CONCLUSION: Clinically significant cardiovascular toxicity associated with supplement use is a fortunately rare phenomenon that can occur via multiple mechanisms. Clinicians should maintain awareness that supplements may produce serious and sometimes life-threatening cardiovascular poisoning.