Citrus Aurantium (Bitter Orange) Series encompasses standardised extracts from the immature fruit peel of Citrus aurantium, primarily standardised for synephrine content (typically 6–30%). Synephrine is an adrenergic amine that stimulates beta-3 adrenergic receptors, increasing thermogenesis and lipolysis without the cardiovascular side effects associated with ephedrine, making it the most widely used stimulant-based weight management ingredient post-ephedra ban.
Applications:
- Thermogenic weight management and fat-burning formulations
- Pre-workout and energy supplement blends
- Appetite suppression formulations
- Metabolic health and body composition supplements
Key Features & Benefits:
- Synephrine — beta-3 adrenergic thermogenic without ephedrine risks
- Available in multiple standardisations (6%, 10%, 30% synephrine)
- Clinically studied for thermogenesis and metabolic rate elevation
- No animal substance – halal-certified
- Synergistic with caffeine and green tea extract
p-Synephrine, and what to exclude
The main protoalkaloid in bitter orange (Citrus aurantium) is p-synephrine. Its structural isomer m-synephrine (phenylephrine) is a drug substance that is not normally found in bitter orange, so finding it suggests adulteration with synthetic material. Ask for an HPLC profile that reports p-synephrine and shows m-synephrine as not detected. Related amines such as octopamine, tyramine and N-methyltyramine may also be reported.
Grades and source
Extracts are made from the dried immature fruit and standardised to different p-synephrine levels. Higher grades need more processing, so ask for the extraction solvent and the carrier used to reach the stated figure.
Regulatory and labelling
Synephrine products are regulated differently from market to market. Some authorities set limits or warnings, especially when synephrine is combined with caffeine. Check the rules of your market before formulating with Guarana Extract, Green Tea Extract or other caffeine sources.
What the research says
- A 2022 systematic review and meta-analysis of 18 articles on placebo-controlled human trials found that prolonged use of synephrine raised systolic blood pressure by about 6.4 mmHg and diastolic by about 4.3 mmHg. Weight loss after prolonged use was not significant, and body composition did not change. The authors found no evidence that synephrine helps weight loss, and called for more studies on its safety and efficacy. [1]
- An earlier 2004 systematic review found only one eligible randomised placebo-controlled trial (20 patients, 6 weeks). It showed no statistically significant benefit for weight loss and gave limited safety information. [2]
These summaries describe published research on the ingredient. They are not claims for any finished product; claims on finished products must meet the rules of the market where they are sold.
References
- Koncz D, et al. The safety and efficacy of Citrus aurantium (bitter orange) extracts and p-synephrine: a systematic review and meta-analysis. Nutrients. 2022;14(19):4019. doi:10.3390/nu14194019
- Bent S, Padula A, Neuhaus J. Safety and efficacy of citrus aurantium for weight loss. Am J Cardiol. 2004;94(10):1359-1361. doi:10.1016/j.amjcard.2004.07.137
What to ask for on the certificate of analysis
- Botanical name and plant part (Citrus aurantium, immature fruit)
- p-Synephrine content by HPLC
- m-Synephrine (phenylephrine): not detected, by HPLC
- Octopamine, tyramine and N-methyltyramine, if specified
- Extraction solvent, carrier with its percentage, and residual solvents
- Loss on drying, heavy metals (lead, arsenic, cadmium, mercury) and pesticide residues
- Microbiology: total plate count, yeast and mould, E. coli, Salmonella
- Batch number, manufacture and retest dates
