Ephedra: Not the Only Bully on the Block

You probably already know to steer clear of ephedra if you’re trying to slim down. The herb can cause serious heart problems, even death. But it turns out that ephedra may not be the only dangerous ingredient in herbal weight loss supplements.

Some other substance in an herbal weight-loss formula called Metabolife 356—which accounts for an estimated $500 million in annual sales—can change the rhythm of a person’s heartbeat enough to potentially cause heart attacks, a recent study found.

Researchers at the University of Connecticut in Storrs gave 15 young, healthy people either a dummy pill or a tiny dose of Metabolife 356. Then doctors monitored the volunteers’ hearts for several hours. Even after taking just one-sixth of what the label recommended, those who took Metabolife showed a lengthening of time between heartbeats, a risk factor for sudden cardiac death.

And while the product does contain ephedra (listed on the ingredient label under its Chinese name, ma huang), lead researcher Brian McBride doesn’t think it’s the culprit. The heartbeat measurement he used, called the QTC interval, is only affected by ephedra in people who have potassium deficiencies in their hearts. Since the people in his study were young and healthy, it’s unlikely that ephedra alone was lengthening their QTC intervals.
The researchers plan to keep testing Metabolife to find out what else might be causing the problems, but in the meantime, McBride says, don’t rely on weight loss pills for shedding pounds—they’re just not worth the risks.