Study Affirms Bitter Orange Has No Impact on Blood Pressure

Wayne, N.J., December 19, 2005 – The results of a new study on bitter orange (Citrus aurantium) extract show the natural ingredient has virtually no impact on blood pressure or heart rate, giving additional credence to findings from earlier studies.

Results from the double-blind, randomized, placebo-controlled, crossover study ‑ conducted by researchers from the University of Connecticut and Hartford (Conn.) Hospital ‑ appear in the Winter 2005 issue of Pharmacotherapy, the journal of human pharmacology and drug therapy. On alternating weeks, the researchers provided test subjects with either the placebo or bitter-orange dried-fruit extract (450 mg standardized to 27 mg of synephrine) with a washout period in between.

The team of four doctors and researchers were led by Bokyung Min, Pharm.D., of the University’s School of Pharmacy and the division of Drug Information at Hartford Hospital. Together, they measured the rate-corrected QT (QTc) interval and blood pressure before dosing subjects with bitter orange extract or placebo and then again at one, three, five and eight hours after dosing. The QT interval is part of the normal heart electrical activity seen in an electrocardiogram (EKG). Substances that lengthen this interval are thought to be risk factors for the heart.

In the published findings, it was noted that subjects receiving bitter-orange extract versus the placebo had similar post-dose QTc interval, systolic blood pressure, and diastolic blood pressure. All test subjects were healthy adult volunteers.

“Bitter orange dried-fruit extract standardized to … synephrine 27 mg did not significantly alter the QTc interval or blood pressure after a single dose was administered,” the researchers wrote in their report.

Bob Green, president of Nutratech, the exclusive worldwide distributor for patented bitter orange ingredient Advantra Z®, said these positive results are encouraging to all who use Advantra Z in their formulas. “Bitter orange has been around for hundreds of years in traditional Chinese medicine, and continues to be a leading ingredient for weight loss and sports nutrition.”

Other recent studies, including a project led by Dr. Christine Haller at the University of California, San Francisco, also showed negligible increases in heart rate and no increase in blood pressure among test subjects, even though subjects in that study received higher concentrations of bitter orange than did those in the Min study. In the Haller study, heart rate increases were reported among all study groups following a meal, which is a natural result of digestion.

Nutratech recommends all consumers – particularly those with hypertension, heart disease or other pre-existing conditions – consult with their health care providers before embarking on a dietary supplement regimen of any sort.

Dr. Min’s work was supported by an unrestricted educational grant from Pfizer Inc. in Groton, Conn. The report is entitled “Absence of QTc-Interval-Prolonging or Hemodynamic Effects of a Single Dose of Bitter-Orange Extract in Healthy Subjects.”

Efficacy and safety studies conducted on Advantra Z / bitter orange can be viewed in their entirety at

Nutratech, Inc., provides innovative, proprietary and patented nutraceutical ingredients to the dietary supplement, weight management, sports nutrition, beverage and food industries. The company is headquartered in Wayne, N.J.


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