Bob Green, president of Nutratech, Inc. - the firm behind patented bitter orange (Citrus aurantium) extract Advantra Z - said that the doses used in new FDA study with lab rats were 13 to 43 times the typical human dosage.
“The results of the study cannot be directly applied to the Citrus aurantium / p-synephrine used in dietary supplements.”
Bitter orange is claimed to increase energy expenditure, facilitate the breakdown of fat and increase glucose uptake by muscles, and is widely used in weight management and sports nutrition supplement.
As reported by NutraIngredients-USA, a multi-component extract of bitter orange was reported to raise blood pressure and heart rate in lab animals (Toxicology and Applied Pharmacology, Vol. 261, pp. 236-247).
Clinically significant?
After consultation with Dr Sidney Stohs, dean emeritus of the Creighton University School of Pharmacy and Health Professions, Green added: “Regarding the increase in heart rate and blood pressure - which the study noted ranged from 4% to 11.5% - it’s important to understand that heart rate and blood pressure will increase 10% to 20% with moderate exercise or simply walking up a flight of stairs.
“So while statistically significant, the statistics in the Hansen study are not clinically significant or relevant to humans.”
Dr Stohs has worked as a consultant for Nutratech Inc, and recently authored a review that concluded that safety concerns and adverse events associated with bitter orange and p-synephrine are ‘unwarranted and unjustified’ (Journal of Functional Foods, 2010, Vol. 2, pp. 235-238).
Green added that over 15 studies have confirmed the safety of bitter orange and p-synephrine, and that “manufacturers can be very confident about including these ingredients in their dietary supplements”.
Increasing profile
The profile of bitter orange/synephrine increased following the FDA ban on ephedra in 2004 as it contains similar compounds and was favored by dietary supplements manufacturers as an ephedra substitute.
Some suppliers have also reported a surge in enquires from manufacturers looking for alternatives to controversial ingredient DMAA in the wake of the FDA’s recent crackdown on the stimulant.
P-synephrine is not banned by WADA, the FDA or Health Canada, and the latter recently changed its guidelines and concluded that 1 to 50 mg per day is “not likely to cause any adverse health consequences”.