Bitter orange

The name "bitter orange", also known as Seville orange, sour orange, bigarade orange, and marmalade orange, refers to a citrus tree (Citrus aurantium) and its fruit. Many varieties of bitter orange are utilized for their essential oil, which is used in perfume and as a flavoring. Bitter orange is also employed in herbal medicine as a stimulant and appetite suppressant. Slivers of the rind are used to give marmalade its characteristic bitter taste.




After the U.S. Food and Drug Administration banned the herbal stimulant ephedra, manufacturers substituted bitter orange in many herbal weight-loss products,[2] despite similar concerns about potential serious side effects and lack of effectiveness.[3][4] In a recent article by the publication Consumer Reports, it was furthermore reported that use of bitter orange may be associated with "fainting, heart-rhythm disorders, heart attack, stroke, [and] death".[5]

Uses
The extract of bitter orange (and bitter orange peel) has been used in dietary supplements as an aid to fat loss and as an appetite suppressant, although in traditional Chinese medicine it is always prescribed in concert with other support herbs, not alone. Bitter orange contains the tyramine metabolites N-methyltyramine, octopamine and synephrine,[9] substances similar to epinephrine, which acts on the α1 adrenergic receptor to constrict blood vessels and increase blood pressure and heart rate.[10][11]




Following bans on the herbal stimulant ephedra in the U.S., Canada, and elsewhere, bitter orange has been substituted into "ephedra-free" herbal weight-loss products by dietary supplement manufacturers.[2] While bitter orange has not undergone formal safety testing, it can cause the same spectrum of adverse events as ephedra.[12] Case reports have linked bitter orange supplements to strokes,[13][14] angina,[9] and ischemic colitis.[15]



The National Center for Complementary and Alternative Medicine found that "there is currently little evidence that bitter orange is safer to use than ephedra."[4] There is no evidence that bitter orange is effective in promoting weight loss.[3]



Following the presentation of a healthy young man with a myocardial infarction (heart attack), a case study and subsequent literature review found that the makers of "nutritional supplements" who replaced ephedrine with its analogs p-synephrine and/or p-octopamine from "bitter orange" had in effect simply found a loophole in the FDA's April 2004 regulation banning ephedra in those supplements by substituting a similar substance the regulation did not address, while permitting them to label the products as "ephedra-free".[16]

Drug interactions
Bitter oranges may seriously interact with drugs such as statins in a similar way to grapefruit.[17]