Weight loss supplements that have stepped in to replace banned ephedra products carry the same heart risks, a research concludes.
Researchers at the University of California, San Francisco, say weight loss products containing bitter orange cause similar effects to ephedra, including increased heart rate and blood pressure. Their study appears in the American Journal of Medicine.
Ephedra is a plant-derived stimulant that was promoted for weight loss and to boost energy levels. While it is still allowed to be used in Canada in small doses in nasal decongestants, it is not approved for weight loss, appetite suppression, or similar uses. It is particularly dangerous when combined with caffeine or other stimulants, as is the case in many such supplements. In Canada, this combination has been blamed for at least one death, while in the US, the death in 2003 of 23-year-old Baltimore Orioles pitcher Steve Bechler, who used an ephedra supplement, helped prompt a ban.
Since then, numerous supplements have popped up in its place, including ones with bitter orange - also known as Sevilla orange or citrus aurantium - which contains synephrine, a chemically-similar compound to the active ingredient in ephedra. But until now, little was known about the effects of these products.
The researchers set out to test the safety of bitter orange products with a study involving 10 healthy adults between the ages of 18 and 42. Participants were instructed to avoid caffeine, over-the-counter drugs, and herbal products for 24 hours before the study began.
Each participant randomly received a single dose of either Advantra Z, which contains 46.9 mg of synephrine, Xenadrine EFX, which contains 5.5 mg of synephrine along with 239.2 mg of caffeine and 5.7 mg of a compound called octopamine, or a placebo (inactive imitation medication). Participants eventually tried all three of the treatments, with a period of at least a week between each.
Heart rate and blood pressure were measured one hour before participants received their supplements and then checked again at the time participants received their dose, as well as 30, 60, and 90 minutes and two, three, four, five, six, eight, and 12 hours after. Blood samples were taken at the same time, starting when participants received their doses. Participants also rated their physical symptoms, moods, and emotions on a questionnaire at the time they received their dose and then again after one, two, and six hours.
While Advantra Z did not have any significant effects on blood pressure, Xenadrine EFX raised both systolic (the upper number) and diastolic blood pressure by an average of about 9 mm Hg each after two hours. Both treatments also significantly raised heart rates, with a peak of about 11 beats per minute for Advantra Z and nearly 17 extra beats per minute for Xenadrine EFX six hours after taking the medication.
These findings indicate that re-formulated weight loss supplements have similar acute cardiovascular stimulant actions as banned ephedra products and could cause adverse health effects in some individuals," write Dr. Christine A. Haller and colleagues.
But they go on to conclude that the bitter orange alone is not likely responsible, as evidenced by the fact that the amount of synephrine in Advantra Z - which far outweighs that in Xendarine EFX - does not cause a significant boost in blood pressure, whereas Xenadrine EFX does. They add that an interaction between synephrine and caffeine could be to blame.
"Physicians should caution patients about the use of ephedra-free weight-loss dietary supplements and monitor blood pressure in those who choose to use these supplements," the researchers conclude. "Individuals with hypertension, heart disease, or other pre-existing conditions that could be exacerbated by the sympathomimetic effects of botanical stimulants should avoid use of these products."
There's no quick fix for weight loss, but it is possible to shed pounds safely. So before you start a diet or add a supplement to your weight-loss regime, talk to your doctor.