Quality assessment of selected vitamins and minerals in effervescent food supplements

Effervescent tablets (ETs) are a popular form of food supplement due to their convenience and taste. However, their quality and regulatory compliance remain insufficiently investigated. This study assessed the composition and labelling quality of ETs, focusing on vitamins (D, B12, C) and the minerals zinc, calcium, magnesium, and iron. Altogether, 71 products were purchased in Slovenia, mostly international brands (87.3 %). The purchased samples were analysed, using standards applicable to food control authorities. The laboratory analyses revealed that overall 11 % of the products deviated from the declared nutrient values beyond permitted tolerance limits, with the highest non-compliance (24 %) observed in ETs containing vitamin D. Over half of the products (55 %) contained at least one micronutrient exceeding the reference daily intake values, and 18 % surpassed established Tolerable Upper Intake levels (ULs), raising safety concerns. All majority of these cases were linked to magnesium content. Although most products declared the chemical forms of nutrients, 14 % did not provide this information. Additionally, 13 % of the declared health claims failed to comply with EU regulatory standards. This study highlights major substantial shortcomings in the quality control, labelling transparency, and regulatory compliance of ET. The results call for stronger oversight, harmonised standards, and better consumer awareness.