Nov 11, 2026 - Foods
Zinc and Vitamin C in dietary supplements: content and labeling under review
Dietary supplements containing zinc and vitamin C pose particular demands on the control of composition and labeling. For manufacturers and distributors it is therefore important to verify the actual nutrient contents and to comply with applicable labeling regulations.
A recent product test by ÖKO-TEST with 21 preparations shows that individual products exhibited discrepancies between declared and analytically determined nutrient contents as well as deficiencies in labeling.
Overall, only four preparations complied with the Federal Institute for Risk Assessment (BfR) maximum recommended amounts for zinc and vitamin C. Seven products contained higher amounts than recommended for both nutrients. The measured contents ranged from 12 to 1,000 mg vitamin C and from 2.25 to 15 mg zinc per daily dose, so some preparations were rated "poor" or "insufficient". Among the labeling issues, incorrectly worded or unauthorized health claims were found.
The results underscore the importance of reliable analytical control and legally compliant labeling for the quality and marketability of dietary supplements.
In our Tentamus laboratories we carry out analyses of zinc and vitamin C contents as well as the labeling of dietary supplements and other foods.
We provide fast and reliable results and are happy to advise you on all matters related to product safety. If you have any questions, our customer advisors are available to assist you.
Sources: