Assessment of Zinc Content in Food Supplements

Zinc (Zn) is an essential trace element that plays a key role as a cofactor for over 300 enzymes involved in metabolic processes, protein synthesis, and gene expression regulation. Zn supplementation is used in the prevention and treatment of infectious, dermatological, and reproductive system diseases. Legal regulations allow for a relatively wide range of mineral content in this product category (from −20% to +45% of the declared value). The study aimed to analyze the quality of food supplements containing Zn—compliance with declared Zn content was assessed. The study included 80 preparations. The preparations varied in terms of declared Zn content, pharmaceutical form, chemical form of Zn, composition, and primary mode of action. Zn content was determined by atomic absorption spectrometry after prior mineralization of the samples in concentrated nitric acid in a closed microwave system. It was estimated that 70% of food supplements contained Zn within the acceptable range. It should be emphasized that 23.75% of the preparations contained more Zn than the permissible range of Zn content, and 6.25% contained less—both of these groups of preparations may be associated with a health risk. From a regulatory perspective, these results highlight the need for continuous surveillance of the food supplement market to improve consumer safety.