Key result
Bitter orange extract shows no stimulant effects on HR, BP, or ECGs compared to placebo.
Why the study?
Does oral p-synephrine (49 mg) cause cardiovascular stimulatory effects in healthy subjects?
RCT (n=18)
Double-blind
Randomized
Does oral p-synephrine (49 mg) cause cardiovascular stimulatory effects in healthy subjects?
Oral p-synephrine (49 mg) does not act as a cardiovascular stimulant or cause significant adverse effects in healthy subjects over an 8-hour period.
Supports short-term cardiovascular safety of 49 mg p-synephrine; confirms absence of stimulatory effects in this RCT.
Bitter orange (Citrus aurantium) extract and its primary protoalkaloid p-synephrine are widely consumed in combination with multiple herbal ingredients for weight management and sports performance. p-Synephrine is also present in juices and foods derived from a variety of Citrus species. Questions exist regarding the safety of p-synephrine because of structural similarities with other biogenic amines. This study assessed the cardiovascular (stimulatory) effects of bitter orange extract (49-mg p-synephrine) given to 18 healthy subjects (nine men and nine women) in a double-blinded, placebo-controlled cross-over study. Heart rates, blood pressures, and electrocardiograms were determined at baseline, 30, 60, 90 min, 2, 4 , 6, and 8 h. Blood samples were drawn at baseline, 2 h and 8 h for serum chemistries, blood cell counts, and p-synephrine and caffeine levels. No significant changes occurred in electrocardiograms, heart rates, systolic blood pressure, blood chemistries, or blood cell counts at any time point in either control or p-synephrine treated group. A small (4.5 mmHg) decrease in diastolic blood pressure occurred in the p-synephrine treated group at 60 min. No adverse effects were reported. Caffeine ingestion varied markedly among the participants. p-Synephrine does not act as a stimulant at the dose used.
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Shara et al. (2016) conducted an RCT in Healthy Subjects (n=18). Bitter orange extract (p-synephrine) vs. Placebo was evaluated on Cardiovascular (stimulatory) effects including heart rates, blood pressures, and electrocardiograms. Bitter orange extract containing 49-mg p-synephrine did not act as a stimulant, producing no significant changes in heart rate, systolic blood pressure, or electrocardiograms compared to placebo.
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