A botanical used in some weight-loss products as a substitute for now-banned ephedra may possibly pose health risks of its own. And it may not even work, according to research review.

The ingredient is an extract of the Seville orange, known scientifically as Citrus aurantium. According to the authors of the new report, there is no reliable evidence that the herb works, but there is evidence that it could raise blood pressure or interact with certain medications.

Since the U.S. Food and Drug Administration’s recent ban on ephedra, ephedra-free herbal weight-loss supplements - including many containing Citrus aurantium - have quickly emerged to fill the gap.

Ephedra was pulled from the market after being linked to cases of heart attack, stroke and high blood pressure; at the time that the U.S. ban was announced late last year, the FDA had received reports of 155 deaths among ephedra users.

Citrus aurantium contains a compound called synephrine that, like ephedra, stimulates the central nervous system and may boost metabolism. And it may also cause some of the same adverse effects linked to ephedra, report Drs. Adriane Fugh-Berman and Adam Myers of Georgetown University in Washington, D.C.

There have yet to be any reports of serious side effects with Citrus aurantium, according to the researchers, but scientists know that synephrine can raise blood pressure and has the potential to raise the risk of cardiovascular complications.

In addition, they point out, the juice of the Seville orange, like grapefruit juice, can raise blood levels of certain drugs, and therefore the risk of side effects. Studies have found that Citrus aurantium can interact with the HIV drug indinavir (Crixivan) and the blood-pressure medication felodipine (e.g., Plendil).

The review, published in the journal Experimental Biology and Medicine, also looked at the only published trial of a Citrus aurantium-containing weight-loss aid. It showed that the herbal product was no better than a placebo at helping people shed pounds, according to Fugh-Berman and Myers.

The researchers acknowledge that Citrus aurantium has been used for thousands of years in Chinese medicine for digestive problems, and that this can be viewed as a sign of its safety.

They add, however, “The same argument has been used for ephedra.”

The Seville orange itself is not widely consumed owing to its taste - it’s also called the “sour” or “bitter” orange - and extracts of the fruit, when used medicinally, have traditionally been used for short periods.

It’s unclear, according to the Georgetown researchers, what the effects of taking C. aurantium in a weight-loss aid might be.

Earlier this year, shortly after the ephedra ban took effect, the FDA said it was compiling information on the safety of several ephedra substitutes, including Citrus aurantium, being touted for weight loss.

Consumers should avoid weight-loss products containing Citrus aurantium extracts, Myers and Fugh-Berman conclude, until their safety and effectiveness is established.

SOURCE: Experimental Biology and Medicine, September 2004.