A recent article in Consumer Reports (September 2010) listed bitter orange–a popular weight management and sports nutrition ingredient–as potentially unsafe. From a scientific perspective, this is unjustified. Research has discredited the “possible dangers” listed in the article. And, no serious adverse events have ever been shown to be caused by bitter orange. Consumer Reports either lacks understanding of bitter orange’s chemistry or failed to carefully review the scientific literature.

• You must understand the chemistry of bitter orange.  Its dominant alkaloid is p-synephrine. p-Synephrine primarily stimulates beta-3 receptors, which increase thermogenesis and lipolysis, but don’t affect blood pressure.  p-Synephrine is often confused with m synephrine, found in nasal decongestants and sprays, which impacts alpha, beta-1 and beta-2 “excitory” receptors, increasing blood pressure and heart rate. m-Synephrine does not appear to be inherent in bitter orange, and a test of the patented bitter orange extract, Advantra Z, showed it was not present at all.
• Bitter orange is different than ephedrine.  Scientists understand that the p-synephrine found in bitter orange is structurally similar to ephedrine, but pharmacologically different.These differences alter bitter orange’s lipid solubility, so it doesn’t cross the blood brain barrier into the central nervous system. Consequently, bitter orange exhibits little if any of ephedrine’s stimulant effects.
• Bitter orange’s margin of safety exceeds that of most prescription and over-the-counter drugs, which are associated with 100,000 deaths each year. More than 100 million doses of products containing bitter orange have been consumed in the U.S.–as dietary supplements, fruits and juices–without serious incidents.  Since 1969, there has been an average of only four adverse event reports related to bitter orange per year.  Moreover, independent reviews of these reports couldn’t establish bitter orange as the cause of the adverse events since there were many ingredients involved–plus health and lifestyle factors.
• Current research shows that bitter orange is exceedingly safe. Not one of the research studies published over the past eight years reported any serious or significant adverse events directly attributable to bitter orange. Nor did they demonstrate adverse cardiovascular or neurological events. This includes a recent study in human subjects given 50 mg of p-synephrine, which resulted in no heart rate or blood pressure effects relative to subjects given placebos.
• Bitter orange is still paying the price for misstatements by the FDA. In 2004, the FDA anonymously supplied information to two major newspapers indicating that adverse reactions were associated with bitter orange. Independent analysis of the FDA information found that no credible adverse events could be attributed to bitter orange. The FDA admitted as much in The Tan Sheet (September 20, 2004), but has never acknowledged this error in mainstream media.

Unfortunately, this evidence has not prevented scientifically uninformed and politically misguided individuals or the news media from parroting information that is decidedly untrue – or from making statements that are not based on scientific fact.  Such unscientific reporting does not serve Consumer Reports, the natural products industry or the general public. 

Sidney J. Stohs, Ph.D., FACN, CNS, ATS, FASAHP is the Dean Emeritus of the School of Pharmacy and Health Professions, Creighton University Health Sciences Center, Omaha, NE.

Blog posted on WholeFoods Magazine Online, August 23, 2010.