Bitter Orange for Weight Control

Common name: Seville Orange, Zhi Shi, Chongcao

Botanical names: Citrus x aurantium

Why do dieters use it?*

Some dieters say that bitter orange

helps increase calorie burning.
helps suppress appetite.

What do the advocates say?*

Bitter orange (Citrus aurantium) contains several substances known to stimulate metabolic rate, which should increase calorie burning. While no published research has tested it alone, it appears to be effective in combination with St. John’s wort and caffeine.

How much is usually taken by dieters?

Although historically used to stimulate appetite, bitter orange is frequently found in modern weight-loss formulas because synephrine is similar to the compound ephedrine, which is known to promote weight loss. In one study of 23 overweight adults, participants taking a daily intake of bitter orange (975 mg) combined with caffeine (525 mg) and St. John’s wort (Hypericum perforatum, 900 mg) for six weeks lost significantly more body weight and fat than the control group.¹ No adverse effects on heart rate or blood pressure were found. Bitter orange standardised to contain 4 to 6% synephrine had an anti-obesity effect in rats. However, the amount used to achieve this effect was accompanied by cardiovascular toxicity and mortality.²

Are there any side effects or interactions?

Bitter orange oil may possibly cause light sensitivity (photosensitivity), especially in fair-skinned individuals.³ Generally this occurs only if the oil is applied directly to the skin and then exposed to bright light; in rare cases it has also been known to occur in people who have taken bitter orange internally. The oil should not be applied topically and anyone who uses it internally should avoid bright light, including tanning booths.

Internal use of the volatile oil of bitter orange is also potentially unsafe and should not be undertaken without expert guidance. Large amounts of orange peel have caused intestinal colic, convulsions, and death in children.⁴ The amounts recommended above for internal use should not be exceeded.

One text on Chinese medicine cautions against the use of bitter orange in pregnancy.⁵ This concern is not raised in any other reference, and the American Herbal Products Association classifies the herb as "class 1," a herb that can be safely consumed during pregnancy when used appropriately.⁶

Decoctions of bitter orange substantially increased blood levels of cyclosporine in pigs, causing toxicity.⁷ Bitter orange also inhibited human cytochrome P450 3A (CYP3A) in the test tube.⁸ This is an enzyme that helps the liver get rid of numerous toxins, and strongly affects metabolism of certain drugs. Bitter orange might, therefore, interact with drugs that are metabolized by CYP3A. To be on the safe side, bitter orange should not be combined with prescription medications, unless someone is under the care of an experienced natural medicine clinician.

At the time of writing, there were no well-known drug interactions with bitter orange.

Parts used and where grown

The dried outer peel of the fruit of bitter orange, with the white pulp layer removed, is used medicinally. The leaves are also commonly used in many folk traditions. The bitter orange tree is indigenous to eastern Africa, Arabia, and Syria, and cultivated in Spain, Italy, and North America.

Resources

See a list of books, periodicals, and other resources for this and related topics.

*Dieters and weight-management advocates may claim benefits for bitter orange based on their personal or professional experience. These are individual opinions and testimonials that may or may not be supported by controlled clinical studies or published scientific articles on bitter orange. For more complete and detailed information, including references and safety information, see Bitter Orange as an herbal remedy.

References
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1. Colker CM, Kalman DS, Torina GC, et al. Effects of Citrus aurantium extract, caffeine, and St. John’s wort on body fat, lipid levels, and mood states in overweight adults. Curr Ther Res 1999;60:145–53.

2. Calapai G, Firenzuoli F, Saitta A, et al. Antiobesity and cardiovascular toxic effects of Citrus aurantium extracts in the rat: A preliminary report. Fitoterapia 1999;70:586–92.

3. Blumenthal M, Goldberg A, Brinckmann J, eds. Herbal Medicine: Expanded Commission E Monographs. Newton, MA: Integrative Medicine Communications, 1999.

4. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association’s Botanical Safety Handbook. Boca Raton, FL: CRC Press, 1998.

5. Bensky D, Gamble A, Kaptchuk T. Chinese Herbal Medicine: Materia Medica, rev ed. Seattle: Eastland Press, Inc., 1993.

6. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association’s Botanical Safety Handbook. Boca Raton, FL: CRC Press, 1998.

7. Hou YC, Hsiu SL, Tsao CW, et al. Acute intoxication of cyclosporine caused by coadministration of decoctions of the fruits of Citrus aurantium and the pericarps of Citrus grandis. Planta Med 2000;66:653–5.

8. Guo LQ, Taniguchi M, Chen QY, et al. Inhibitory potential of herbal medicines on human cytochrome P450-mediated oxidation: Properties of umbelliferous or citrus crude drugs and their relative prescriptions. Jpn J Pharmacol 2001;85:399–408.

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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or chemist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires March 2007.