Quantitative control of dietary supplements containing caffeine

European legislation is more permissive regarding authorizing a dietary supplement than a pharmaceutical. There are many caffeine-containing dietary supplements that are used as energizing or lipolytic (weight loss) supplements [1,2]. The term “dietary supplement” often misleads the consumer, assuming that the active principles are of vegetal origin.The purpose of the study was to compare the caffeine concentration declared by the manufacturer with that actually present in the dietary supplements containing green tea or guarana extract [3]. Therefore, 5 dietary supplements were analyzed by HPLC-UV and the amount of caffeine contained in each supplement was compared with the declared one. Results: The 5 dietary supplements had a reported caffeine content of 80 to 160 mg / tablet/capsule, but the actual caffeine content determined by HPLC exceeded the one declared by the manufacturer by 30-60 %. The highest differences were found in preparations also containing guarana or green tea extract with known caffeine content. If different plant extracts containing the same active substance are combined, the manufacturer should declare the total cumulative dose of the active principle in order to avoid side effects or even some pharmacodynamic or pharmacokinetic interactions between the dietary supplement and a possible chronic medication.

• References

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