Slimming dietary supplement potentially dangerous

A popular dietary supplement (Metabolife 356) which is commonly used as a slimming aid could be potentially dangerous after US researchers have found that it can increase systolic blood pressure and the maximal QTc interval of the heart. This can potentially lead to an increased risk of stroke or dangerous arrhythmias. Meanwhile US authorities have moved to ban one of the active ingredients (Ephedra) from general use.

The dietary supplement Metabolife 356, used as a slimming aid by many in the US can increase systolic blood pressure and maximal QTc interval, US researchers warn. Metabolife 356 containse Ephedra and caffeine among its 19 ingredients and is the top selling slimming product in the US.Finding anecdotal evidence of cardiovascular and cerebrovascular adverse events relating to use of the product, Brian McBride (Hartford Hospital, Connecticut) and colleagues conducted a double-blind trial of the supplement. Fifteen healthy volunteers were randomly assigned to either a single dose of Metabolife 356 or matching placebo, administered in a crossover fashion with a 7-day washout period in between treatments. The maximal QTc interval and blood pressure were monitored immediately before dosing, and at 1, 3, and 5 hours afterwards. The results show that individuals receiving the herbal supplement had a significantly longer maximal QTc interval than those receiving placebo (419.4 vs 396.1 milliseconds, p<0.001), and also higher mean systolic blood pressure (123.5 vs 118.93 mmHg, p=0.009). In addition, patients receiving the supplement were more likely to experience a QTc interval of at least 30 milliseconds compared with those receiving placebo (eight individuals versus one, relative risk=2.67). An increase in the systolic blood pressure is associated with an increased risk of cerebrovascular accidents (stroke), while an incresed QTc interval can lead to deadly ventricular arrhythmias, in particular 'torsades de pointes". The research team noted that the European Center for Proprietary Medicinal Products recognizes that a drug-induced increase in the QTc interval of at least 30 milliseconds is a potential cause of concern for developing torsade de pointes. The team concluded that "Metabolife 356 and products sharing similar ingredients should be avoided until more information is known".Meanwhile, US health officials have said they will ban the main constituent of Metabolife 356 (the herb ephedra) because it poses unreasonable risks such as heart attacks and strokes. The move marks the first time the government has outlawed a dietary supplement and will set a legal precedent for action against other risky products. Ephedra drew heightened attention after the February death from heatstroke of Baltimore Orioles pitching prospect Steve Bechler. A Florida medical examiner stated that ephedra supplement contributed to his death. In addition, the FDA has reports of 155 deaths of people who took ephedra and more than 16,500 complaints. Mr McClellan said the FDA combed through scientific studies. The ban was based not only on reported health problems - including deaths - but also on understanding how ephedra works, he said. "Ephedra is an adrenaline-like stimulant that can have potentially dangerous effects on the heart," an FDA statement said. To outlaw a dietary supplement, the government must prove the product poses an unreasonable risk.Meanwhile, makers insist ephedra, also known as 'ma huang', is safe when taken as directed. Metabolife International, which earlier this year said it was removing ephedra from its most popular diet pill, stated: "Millions of consumers throughout the United States have used ephedra dietary supplements as a safe, inexpensive and effective means by which to support weight loss," the company said in a statement. "Metabolife will carefully consider its options," the company said. Several medical groups immediately welcomed the ban. "Dietary supplements containing ephedra are a serious health threat," Dr Ron Davis, a trustee for the American Medical Association, said in a statement. "Seizure, stroke, psychiatric problems, heart attack and death are all recognised risks of ephedra use," he said. Officials said on Tuesday they were sending letters to 62 manufacturers to notify them about the impending ephedra ban. Some retailers such as NBTY, CVS and General Nutrition Centres halted sales of ephedra-based diet products this year. Many manufacturers also stopped using ephedra and started promoting alternative diet products. JAMA 2003; 291: 216-221Reuters