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Bitter Orange Citrus Bioflavonoids

Also known as: Citrus aurantium, Bitter orange, Seville orange, p-synephrine

Overview

Citrus aurantium, commonly known as bitter orange, is a citrus tree utilized in dietary supplements for its peel and extract. The primary active compound, p-synephrine, is a protoalkaloid structurally similar to ephedrine but with distinct pharmacological effects. Bitter orange extract is primarily marketed for weight loss, fat reduction, and sports performance enhancement. Research on bitter orange and p-synephrine is moderate, with several clinical studies and reviews available. However, long-term studies are needed to fully ascertain its efficacy and safety. Available evidence includes RCTs and meta-analyses, but findings are inconsistent, particularly concerning cardiovascular effects and weight loss efficacy. It is available in various forms, including capsules, tablets, and as part of complex supplements.

Benefits

Some studies suggest that bitter orange extract containing p-synephrine can increase resting metabolic rate and energy expenditure. For example, one study showed a significant increase in basal metabolic rate and modest weight loss. However, a systematic review and meta-analysis found that weight loss in the p-synephrine group was non-significant after prolonged treatment and did not influence body composition parameters. Benefits are primarily observed in overweight or obese individuals. The effect sizes for weight loss are generally small. Benefits, if any, are typically observed over a period of 6-12 weeks. Longer-term studies are lacking.

How it works

p-Synephrine acts as an adrenergic receptor agonist, primarily affecting the beta-3 adrenergic receptors, which can increase metabolic rate and fat oxidation. It interacts with the cardiovascular and metabolic systems, potentially increasing heart rate and blood pressure. The primary target is the beta-3 adrenergic receptor. The absorption and bioavailability of p-synephrine are not extensively studied, but it is generally assumed to be absorbed when ingested as part of a dietary supplement.

Side effects

The safety profile of bitter orange extract and p-synephrine is a subject of ongoing debate. While many studies have not reported significant adverse events, there are concerns about cardiovascular effects, particularly when combined with caffeine. Increased heart rate and blood pressure have been noted in some studies. Potential interactions with caffeine and other stimulants may exacerbate cardiovascular effects. Individuals with cardiovascular conditions or those taking medications that interact with adrenergic receptors should exercise caution. Pregnant or breastfeeding women, and individuals with hypertension or other cardiovascular conditions, should avoid using bitter orange extract due to the potential for increased blood pressure and heart rate.

Dosage

The minimum effective dose is not well established, but typical doses range from 10-53 mg of p-synephrine per day. Optimal dosages are not clearly defined, but most studies use doses between 10-53 mg/day of p-synephrine, often in combination with other ingredients like caffeine. The maximum safe dose is not established, but doses above 53 mg/day of p-synephrine are less commonly studied. Timing of administration is not specifically studied, but it is generally recommended to take it before meals or workouts. The form does not significantly affect the efficacy or safety profile.

FAQs

Is bitter orange extract safe?

While many studies do not report significant adverse events, there is a concern about the potential for increased blood pressure and heart rate, especially when combined with caffeine.

When is the best time to take bitter orange extract?

The optimal timing for administration is not established, but it is often taken before meals or workouts.

What results can I expect from taking bitter orange extract?

Modest weight loss and increased metabolic rate may be expected, but these effects are not consistently supported across all studies.

Is p-synephrine similar to ephedrine?

A common misconception is that p-synephrine has effects similar to ephedrine, but they have distinct pharmacological profiles.

Research Sources

https://www.medsci.org/v09p0527.htm – This study by Colker et al. showed that a supplement containing bitter orange extract led to a significant increase in basal metabolic rate and modest weight loss in overweight subjects. The study involved 20 overweight adults over an 8-week period and found a 1.4 kg reduction in body weight and a 2.9% reduction in body fat.
https://pubmed.ncbi.nlm.nih.gov/30835576/ – This study analyzed case reports and found no direct correlation between adverse events and p-synephrine. The analysis highlighted the lack of systematic assessment of product composition in the reported cases, suggesting that other factors might contribute to the adverse events.
https://academic.oup.com/nutritionreviews/article/82/9/1292/7272715?login=false – This review provides a comprehensive overview of Citrus aurantium and its effects on metabolic rate, weight loss, and cardiovascular safety. It highlights the need for more long-term studies to fully assess the efficacy and safety of bitter orange extract and p-synephrine.
https://pubmed.ncbi.nlm.nih.gov/32497396/ – This study investigates the effects of p-synephrine on lipolysis and energy expenditure. The findings suggest that p-synephrine can increase lipolysis, but the overall impact on weight loss may be limited.
https://pubmed.ncbi.nlm.nih.gov/36235672/ – This systematic review and meta-analysis by Cardile et al. examined the effects of p-synephrine on blood pressure and weight loss. The analysis of 18 articles indicated that p-synephrine increased systolic and diastolic blood pressure but did not significantly facilitate weight loss, highlighting the need for caution in individuals with hypertension.