Synephrine is a substance that occurs naturally in citrus fruits and especially in bitter orange (Citrus aurantium). The substance is increasingly used in dietary supplements since the related substance ephedrine is prohibited. Ephedrine is forbidden because it can be harmful to health. There is currently no specific legislation in the Netherlands for the maximum permitted amount of synephrine in food supplements. According to researchers at RIVM and RIKILT this is however desirable because adverse effects cannot be excluded if dietary supplements with synephrine are used, as concluded by the risk assessment. RIVM has also conducted a broader investigation into the use and risks of sports nutrition supplements.

Effects on the cardiovascular system

Synephrine can increase blood pressure. In addition, synephrine can cause other harmful effects on the cardiovascular system. This aspect is particularly relevant because overweight people, the target group for weight loss, have a higher risk of cardiovascular disease. Synephrine may also interact with various other drugs, affecting their efficacy.The effects of synephrine can also be enhanced in combination with caffeine and/or physical activity.

No safe dosage determined

Due to insufficient data on the safety of synephrine, no safe dosage can be determined at this time. Especially data on effects after long-term use of synephrine is still lacking.
However, an (indicative) maximum permitted amount of synephrine in food supplements can be determined with the help of the available data. The Dutch Food and Consumer Product Safety Authority will shortly publish an advice on this.