Many diet supplements may carry heart risk, study says

From the Canadian Obesity Network

Three quarters of weight-loss supplements bought online as part of a study contained ingredients that could cause lethal heart rhythm disturbances, U.S. researchers said on Thursday.

They tested 12 over-the-counter diet supplements and found eight contained at least one ingredient associated with life-threatening heart complications, such as ventricular arrhythmia and cardiac arrest.

While all of the products included a list of the ingredients, none came with a warning about the potential heart rhythm side effects, leaving most people in the dark about the dangers of their diet pills, the researchers said.

"There is a false sense of safety that consumers have when they are using these," said Dr. Mehdi Razavi of the Texas Heart Institute, who presented his findings at a meeting of the Heart Rhythm Society in San Francisco.

Dietary supplements, including many weight-loss supplements, do not undergo the same regulatory scrutiny by the U.S. Food and Drug Administration as drugs do.

"Many people assume the FDA assures the safety and efficacy of supplements," Razavi said in a telephone interview.

He said the study is the first to examine the potential heart risks of weight-loss supplements purchased online.

Razavi and colleagues chose the 12 diet pills in much the same way a consumer would. They entered the common search terms "diet pills" and "weight-loss supplements" into Internet search engines Google, MSN and Yahoo and picked the top four hits from each.

The investigators bought and examined the products. From the ingredients listed on the labels of each brand, they identified 11 that were associated with at least one report of life-threatening cardiac complications or death.

Razavi did not disclose brand names of the pills they tested. Instead, he offered a list of the troublesome ingredients found in the pills that he said consumers should watch out for.

They even found one ingredient -- a type of ephedra known as Ma Huang root -- that has been banned by the FDA since 2004.

Other potentially dangerous ingredients included bitter orange, also known as Synephrine HCl and Citrus aurantium; green tea, also known as Camellia sinensis; buckwheat, guarana, Korean ginseng, licorice root and caffeine anhydrous.

Some of the substances, such as licorice root, can cause trouble on their own by lowering potassium levels, which could alter the heart's electrical system.

Others, such as green tea, are harmless taken in normal doses, but can amplify the effects of some of the other ingredients.

"We're not saying don't take this stuff," Razavi said. "You just need to be cautious and informed and do your research beforehand."

The same advice goes for doctors, he said, who need to ask questions about what substances their patients are taking, especially if they already have heart problems.