Google Trends data show that, along with ephedrine, searches for bitter orange extract have declined since a peak in 2004, mirroring the trend for searches on ephedrine. The data set does not distinguish whether the searches are based on interest for its efficacy or its alleged harmful side effects, but it does show that, as an ingredient, bitter orange extract isn’t top of mind.
For Dr. Sidney J. Stohs, Dean Emeritus at the Creighton University Medical Center and a consultant for dietary supplement formulators, the fact that bitter orange extract has shared the same fate as ephedrine is an unfortunate one.
“[This review] indicates that p-synephrine cannot be equated with ephedrine and the effects of ephedrine cannot be extrapolated to p-synephrine due to structural differences,” he wrote in his latest review on the extract, published in Phytotherapy Research.
He added that these differences greatly alter receptor binding characteristics, pharmacokinetic properties, and the pharmacological/physiological effects produced.
No report of serious incidents
Dr. Stohs has been a defender of bitter orange extract. One of his earlier reviews of scientific literature on the extract and its active compound p-synephrine was published in November 2010, not long after a Consumer Reports article listed bitter orange extract, a popular weight loss supplement ingredient at the time, as one of its ‘Dirty Dozen’ ingredients with questionable safety. He also maintained the position in a review he co-wrote and published in 2012.
In this latest review, conducted under a grant from manufacturer Novel Ingredients, Stohs added eight new clinical trials using the extract that have been published since his last review, in the period 2012-2016 (he was a co-researcher and co-author in a majority of them) that found bitter orange extract did not cause any adverse side effects.
“In addition to the human studies, tens of millions of doses of bitter orange extract -containing products have been consumed in the USA as well as internationally by millions of individuals without the report of serious incidents,” he added.
The FDA does not ban P-synephrine, and Health Canada loosened up its stance on the compound back in 2011, saying that 1 to 50 mg per day is ‘not likely to cause any adverse health consequences.’
Source: Phytotherapy Research
Published online, DOI: 10.1002/ptr.5879
Safety, Efficacy, and Mechanistic Studies Regarding Citrus aurantium (Bitter Orange) Extract and p-Synephrine
Author: Sidney J. Stohs