BACKGROUND:Bitter orange is one name for the tree, Citrus aurantium. Also known as the Seville orange or the marmalade orange, it is widely cultivated in Mediterranean regions. Its fruit is too bitter to eat, so it is used mainly for making marmalade and as an essential oil for use in perfumes and as a flavouring agent in foods and beverages.
In recent years, bitter orange has also become very popular in weight- loss supplements. In 2004, the US Food and Drug Administration (FDA) banned the sale of ephedra because of numerous adverse effects. Ephedra contains ephedrine, which is a known stimulant and also available as a pharmaceutical. Ephedra had been available as a food supplement, leading to widespread use by those seeking to lose weight or improve sports performance. Ephedra is a prescription-only product in Ireland.
Once the FDA ban came into place, “ephedra-free” products took its place. Within a few months of the ban, about one-third of all herbal weight-loss products contained bitter orange, usually in combination with high doses of caffeine.
Bitter orange contains synephrine, which is closely related to ephedrine. However, synephrine exists as a number of isomers, which are very similar compounds. They all have similar activities in the body, though not identical. Debate continues over which isomers occur naturally in bitter orange and, therefore, which ones should be present in food supplements.
EVIDENCE FROM STUDIES
A small number of clinical trials have studied bitter orange as a weight-loss supplement. At least three have been double-blinded and compared the supplement with a placebo. However, none of them studied bitter orange on its own. All of the supplements contained caffeine along with various other herbs like St John’s wort, ginseng or Gingko. Most of the studies also included an exercise programme.
One of the three studies found no significant benefit from the herbal remedy, and the other two studies found greater weight loss with the supplement than placebo. Over the six to eight weeks of the studies, those taking one of the supplements lost an average of 2-3kg, while those in the placebo groups lost an average of 1-2kg. However, it is not possible to determine from these studies if bitter orange contributed to the weight loss because of all the ingredients contained in each remedy.
Ephedra was taken off the US market because of hundreds of reports of adverse effects. These were primarily heart-related, including increased heart rate and blood pressure, heart attacks and strokes, but also psychiatric disturbances. Purified synephrine has been found to increase blood pressure and lead to similar cardiac effects as ephedrine.
In recent years, a small number of adverse events have been reported for people taking bitter orange. The events are primarily cardiac problems such as those reported with ephedra, including at least two deaths in Canada. For this reason, the US National Center for Complementary and Alternative Medicine has concluded: “There is currently little evidence that bitter orange is safer to use than ephedra.”
Bitter orange contains synephrine which acts as a stimulant on the body. While its effects can be felt, there is almost no evidence that this safely helps people lose weight. The best advice on weight loss continues to be the same basic principles: decrease calorie intake, increase exercise output and find people to support you as you develop a healthier lifestyle.
While safe and effective medications have their place during weight loss, bitter orange does not appear to offer much – unless you like marmalade, which is perfectly safe. It contains next to no synephrine.
In September 2010, the US magazine, Consumer Reports, worked with an independent research group to assess various food supplements. Bitter orange was included in their list of 12 food supplements that consumers should avoid completely. The evidence would support that conclusion.
Dónal O’Mathúna has a PhD in pharmacy, researching herbal remedies, and an MA in bioethics, and is a senior lecturer in the School of Nursing, Dublin City University