News - Hypertension Week of Jan. 18, 2004/ Vol. 3 No. 03

Study: Dietary Supplement With Ephedra, Caffeine Can Raise Blood Pressure

A single dose of a dietary supplement containing ephedra and caffeine can increase blood pressure and affect heart rhythms, according to a study in the January 14 issue of The Journal of the American Medical Association (JAMA).

The U.S. Food and Drug Administration recently announced its intention to ban ephedra because of adverse health effects.

Consumers are drawn to herbal weight-loss supplements containing ephedra and caffeine because of their nonprescription status, direct-to-consumer advertising and the perception that they are safe, according to the study.

"Unfortunately, the perception of safety may be the result of a lack of data," said the researchers, while advising patients to avoid such dietary supplements until more information is known about their safety.

Lead researcher Brian McBride, of the University of Connecticut Schools of Pharmacy, and his colleagues evaluated the impact of Metabolife 356, the best-selling dietary supplement containing ephedra and caffeine, on corrected QT interval duration and systolic blood pressure.

QT interval duration is a measure of the time intervals that occur during the electrical impulses that stimulate the heart to contract. A longer interval can increase the risk of abnormal heart rhythms.

The study involved 15 healthy volunteers with an average age of 27 years who received doses of both the dietary supplement containing ephedra and caffeine and a placebo at differing times in the study.

The participants' heart rate and blood pressure were monitored immediately before taking the supplement or placebo and 1, 3, and 5 hours afterwards.

Individuals receiving the dietary supplement had a longer maximal QT interval and higher systolic blood pressure. Fifty-three percent of the participants had dangerous increases in their corrected QT interval increases while taking the dietary supplement containing ephedra and caffeine.

The Food and Drug Administration has no official standards on corrected QT interval prolongation. However, the researchers point out that the FDA has removed drugs from the market with lower corrected QT interval increases.

Other sources: Journal of the American Medical Association, 2004;291:216-221