What is Citrus aurantium (Bitter Orange)?
Citrus aurantium is the botanical name for bitter orange, also known as Seville orange. The fruit's peel and extract are used in traditional medicine and modern dietary supplements, most notably as an alleged weight-loss aid. Its main active compound is p-synephrine, a protoalkaloid structurally similar to ephedrine, a previously banned stimulant ingredient in supplements. The safety of consuming Citrus aurantium is heavily dependent on the dose, preparation, and individual health factors.
The Role of Synephrine in Citrus aurantium
The presence of synephrine and related stimulants is the primary reason for both the purported effects and the significant safety concerns associated with Citrus aurantium. Synephrine can act as a stimulant, potentially increasing heart rate, blood pressure, and metabolism. While supplement manufacturers have sometimes claimed that it offers the "benefits of ephedra without the risks," this claim is not supported by scientific evidence.
Why Synephrine Raises Concerns
- Cardiovascular Effects: Synephrine can cause rapid heart rate and heart palpitations, making it particularly dangerous for individuals with pre-existing cardiovascular conditions, high blood pressure, or glaucoma.
- Serious Adverse Events: Case reports have linked Citrus aurantium use to serious adverse events, including heart attacks and strokes, especially when combined with other stimulants like caffeine.
- Limited Efficacy for Weight Loss: Research has failed to provide reliable evidence that Citrus aurantium or its synephrine content is an effective aid for weight loss. Studies have been preliminary or involved combination products, making it difficult to isolate the effects of bitter orange alone.
Safety Considerations for Consuming Citrus aurantium
When considering the safety of Citrus aurantium, it's crucial to differentiate between amounts found in food and those used in concentrated supplements. The levels of synephrine and other compounds vary significantly.
Comparison: Food vs. Supplement Consumption
| Feature | Bitter Orange in Food (e.g., marmalade) | Bitter Orange in Supplements (e.g., pills) |
|---|---|---|
| Preparation | Typically made from the fruit's peel and juice; often cooked. | Highly concentrated extracts of the peel and fruit. |
| Dose | Low, in quantities found in normal food consumption. | High, often concentrated to contain fixed percentages of synephrine. |
| Safety Profile | Generally considered safe when consumed in food quantities. | Considered possibly unsafe, especially when combined with other stimulants. |
| Risk of Side Effects | Very low risk. | Significantly higher risk of serious cardiovascular and other side effects. |
| Drug Interactions | Low risk from food amounts. | High risk of interacting with numerous medications, including MAO inhibitors, calcium channel blockers, and stimulants. |
Medication Interactions and Contraindications
Citrus aurantium can interact dangerously with a wide range of medications. This is due to its stimulant properties and its ability to inhibit the cytochrome P450-3A enzyme in the liver, which is responsible for metabolizing many drugs.
Key Interaction Risks
- MAO Inhibitors: The tyramine in Citrus aurantium can cause dangerous side effects, including sudden, severe increases in blood pressure, when combined with MAO inhibitors.
- Stimulants: Combining bitter orange with other stimulants, including caffeine, ephedrine, and ADHD medication, significantly increases the risk of heart problems.
- Calcium Channel Blockers & Cyclosporine: Bitter orange juice or extracts can alter the metabolism of these and other critical medications, potentially affecting their efficacy or increasing their toxicity.
Conclusion
While Citrus aurantium, or bitter orange, may have some traditional uses and is generally safe in food amounts, its use in concentrated dietary supplements presents significant health risks. The stimulant compound, synephrine, has been associated with serious cardiovascular side effects, particularly when combined with other stimulants or taken by individuals with pre-existing heart conditions. Evidence supporting its effectiveness for weight loss is weak and insufficient, especially when weighed against the documented safety concerns. Caution is strongly advised, and it is recommended to avoid concentrated supplements containing bitter orange, especially for individuals with cardiovascular issues or those taking prescription medications. Always consult with a healthcare professional before considering any supplement containing Citrus aurantium.
For more detailed information on supplement safety, consult the National Center for Complementary and Integrative Health.
Further Research and Considerations
- Research Needs: More rigorous, double-blind, placebo-controlled trials are needed to fully establish the efficacy and safety of Citrus aurantium and its compounds.
- Photosensitivity: The peel and essential oil can cause photosensitivity, an increased tendency to react to sun exposure.
- Unregulated Supplements: The supplement market is not tightly regulated, meaning product labels may not accurately reflect the actual content or concentration of active compounds, posing an additional risk.
