Last verified: 17 days ago
Bitter Orange
Also known as: Citrus aurantium, p-synephrine, synephrine, sour orange, Seville orange, zhi shi
Evidence under review. — Not yet rated
Bitter orange extract may slightly boost fat burning during exercise, but carries real cardiovascular risks.
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What it does
Bitter orange is a citrus fruit whose peel and extract contain p-synephrine, a stimulant-like compound. One small clinical trial found a single dose modestly increased fat burning during an hour...
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Evidence quality
Evidence base hasn't been formally rated yet. See research below.
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Clinical dose
No established dose from provided studies
What the Science Says
Bitter orange is a citrus fruit whose peel and extract contain p-synephrine, a stimulant-like compound. One small clinical trial found a single dose modestly increased fat burning during an hour of cycling, while a combination formula with grapefruit and olive extracts improved cholesterol and blood pressure markers over 8 weeks. A separate small trial found the flower distillate improved sleep quality in stressed mothers. Most effects are modest and studied in narrow populations.
What It Doesn't Do
Not proven to cause meaningful weight loss on its own. No evidence it replaces ephedra safely — it has its own cardiac risks. The fat-burning shift during exercise was small and doesn't translate to significant body composition change. No solid evidence it reliably reduces anxiety. Lab findings on cancer cells and cholesterol efflux are not human evidence.
Evidence-Based Benefits
A single dose modestly increases fat burning during one hour of moderate-intensity cycling.
Weak EvidenceEffective at: ~3 mg/kg body weight (acute dose)
Supporting studies (click to view on PubMed):
Bitter orange blossom distillate improved sleep disorder scores in stressed mothers in one small trial.
Weak EvidenceEffective at: No established dose from provided studies
Supporting studies (click to view on PubMed):
A combination formula with bitter orange, grapefruit, and olive extracts improved cholesterol and blood pressure in healthy adults over 8 weeks.
Weak EvidenceEffective at: No established dose from provided studies
Supporting studies (click to view on PubMed):
Absorption & Bioavailability
Unknown — no pharmacokinetic data provided in the available studies
Red Flags to Watch For
- A documented case report links bitter orange supplement use to supraventricular tachycardia and myocardial injury (elevated troponin) in a healthy 38-year-old woman with no prior heart disease
- P-synephrine has sympathomimetic (stimulant) properties that may raise heart rate and blood pressure — especially dangerous when combined with caffeine or other stimulants
- Widely found in weight-loss supplements alongside other stimulants, increasing risk of compounded cardiovascular effects
- Most cardiovascular and fat-oxidation studies used combination products, making it impossible to isolate bitter orange's specific contribution
- Marketed as a safe ephedra replacement, but safety data in long-term use is lacking
Frequently Asked Questions
What does Bitter Orange do?
Bitter orange extract may slightly boost fat burning during exercise, but carries real cardiovascular risks.
What is the effective dose of Bitter Orange?
No established dose from provided studies
Is Bitter Orange safe?
A documented case report links bitter orange supplement use to supraventricular tachycardia and myocardial injury (elevated troponin) in a healthy 38-year-old woman with no prior heart disease
What doesn't Bitter Orange do?
Not proven to cause meaningful weight loss on its own.
Research Sources
- PubMed
- NIH DSLD
This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-05-25