Are dietary supplements containing plant-derived ingredients safe microbiologically?

Dietary supplements, particularly those containing ingredients of natural origin, may contain microbiological contaminants, both bacterial and fungal. The present study evaluated the microbiological purity of selected dietary supplements containing plant-based ingredients before their release to the market, as well as raw materials of plant origin which are used in the production of such supplements. A total of 122 samples of supplements and 30 materials of plant origin were studied, with 92.1% exhibiting different degrees of bacterial contamination. Eight samples (5.3%) were contaminated by aerobic bacteria in amounts exceeding 10⁵ CFU/g. Five (3.3%) of the studied supplements were found to contain bacteria from the family Enterobacteriaceae at a level exceeding 10³ CFU/g. Furthermore, a considerable proportion of the studied samples (86.8%) contained fungal contamination. Microbiological contamination may contribute to a deterioration in quality and stability of dietary supplements. In addition, high levels of pathogenic bacteria and microorganisms may pose a risk to consumers.