What is Bitter Orange and Why is Its Safety a Concern?
Bitter orange, also known as Seville orange or Citrus aurantium, is a fruit-bearing tree native to Asia. Its peel and extract are often used in dietary supplements, particularly those marketed for weight loss and athletic performance. The primary compound of concern is p-synephrine, which is chemically similar to ephedrine, a substance banned by the FDA due to its serious effects on the heart.
Unlike ephedrine, which acts on specific receptors in the body, synephrine's effects are more complex and still under study. However, reports of adverse events, including fainting, heart attacks, and strokes, have been linked to bitter orange supplements, especially when combined with other stimulants like caffeine. This raises serious questions about its safety profile and the appropriate dosage.
Recommended Dosages for Bitter Orange and Synephrine
Due to conflicting research and varying concentrations of synephrine in products, establishing a universally safe dose is challenging. Authorities have provided guidance, but caution is paramount.
- Health Canada: Recommends a daily limit of 30 mg for total synephrine and octopamine combined in natural health products.
- ANSES (French Agency for Food, Environmental and Occupational Health & Safety): Advises that synephrine intake from supplements should not exceed 20 mg per day.
- General Supplements: Some studies suggest that bitter orange extracts containing 50–98 mg per day are safe, but this does not account for potential interactions or individual sensitivities.
- In Food: When consumed in the amounts typically found in food (like bitter orange marmalade), bitter orange is considered likely safe for most people. A whole bitter orange contains approximately 30.6 mg of p-synephrine.
Potential Side Effects and Adverse Reactions
Consuming medicinal doses of bitter orange, especially in supplement form or with other stimulants, can lead to a range of side effects:
- Cardiovascular Issues: Increased heart rate and blood pressure are common, which can lead to more serious events like heart attack or stroke.
- Neurological Effects: Some individuals have reported headaches, including migraines, and feelings of nervousness or agitation.
- Gastrointestinal Distress: High doses, particularly of the volatile oil, can cause intestinal colic.
- Photosensitivity: Applying bitter orange oil to the skin can increase sensitivity to sunlight, raising the risk of sunburn.
Who Should Avoid Bitter Orange?
Certain individuals are at a much higher risk of experiencing adverse effects and should not use bitter orange supplements. This includes:
- Pregnant and breastfeeding women: Due to insufficient safety data.
- Individuals with pre-existing heart conditions: Including high blood pressure, irregular heartbeat (arrhythmia), or long QT interval syndrome.
- People with glaucoma: Bitter orange can potentially worsen this condition.
- Those on MAOIs or other medications: Numerous drug interactions exist, and combining bitter orange with certain medicines can be dangerous.
- Anyone scheduled for surgery: Bitter orange can interfere with heart rate and blood pressure during a procedure. It should be discontinued at least two weeks beforehand.
Drug Interactions and Safety Concerns
Bitter orange has been shown to interact with several types of medication by inhibiting the liver enzyme CYP3A4, similar to grapefruit juice. This can cause dangerously high concentrations of certain drugs in the blood. Specific interactions to be aware of include:
- MAOIs: Can lead to a sharp rise in blood pressure.
- Caffeine and other stimulants: Combining with bitter orange can significantly increase cardiovascular risk.
- Antidiabetes drugs: Bitter orange might lower blood sugar, potentially causing it to drop too low when combined with these medications.
- Drugs metabolized by the liver (CYP3A4 substrates): This includes many common medications, and a healthcare provider should be consulted before use.
Comparison of Bitter Orange Forms and Risks
| Feature | Culinary Bitter Orange (Fruit/Marmalade) | Dietary Supplements (Synephrine Extract) |
|---|---|---|
| Synephrine Concentration | Low, typically providing ~30 mg or less per whole fruit. | High and variable, often standardized to a percentage, ranging from 20 to over 100 mg per serving. |
| Cardiovascular Risk | Low risk for most healthy people, consumed as food. | High risk, especially when combined with other stimulants or at higher doses. |
| Drug Interaction Potential | Moderate, similar to grapefruit juice for certain medications via the CYP3A4 enzyme. | High, especially with compounds like caffeine; should be reviewed with a doctor. |
| Safety for at-risk individuals | Generally still to be avoided by pregnant women or those with heart conditions as a precaution. | Highly discouraged for individuals with heart conditions, high blood pressure, or taking certain medications. |
Conclusion
While bitter orange is used in traditional medicine and foods, its use in concentrated dietary supplements carries significant health risks, primarily due to its synephrine content. Establishing how much bitter orange is safe is complicated by individual health factors, co-administration with other substances like caffeine, and varying product potency. Regulatory bodies have suggested cautious daily intake limits, with some recommending doses as low as 20 mg of synephrine and prohibiting its combination with caffeine. The most prudent course of action is to exercise extreme caution, avoid supplement forms, and consult a healthcare professional before considering bitter orange, especially if you have existing health conditions or take other medications.
For more detailed guidance on supplements, refer to the National Center for Complementary and Integrative Health (NCCIH).
