Background
As use of functional food and herbal combination products is ever increasing,
Conclusions
Most products were bought locally, from credible vendors and they all complied with relevant regulatory requirements. However, products obtained on the Internet contained little to no active substances (24% of samples contained less than 20% declared content), presumably showing no efficacy, or were either found to be likely adulterated or contained very high amounts of active substances, compromising safety in terms of dose-dependent adverse effects (one sample containing andrographolides) and pharmacokinetic interactions (one sample containing piperine). In conclusion, consumers should refrain from purchasing such products from the Internet and obtain them only from verified suppliers such as local pharmacies or health stores. Novelty and scientific contribution: This work demonstrates the first developed method for the analysis of aforementioned combination products, which are on the rise today. The method is simple and robust and can be adapted by most laboratories for routine quality control of the said products. Moreover, the work sheds light on the low quality of several products and signifies the need for increased consumer awareness of dangers of taking such products.