Microbial contamination of select dietary supplements

Abstract

One hundred thirty-eight dietary supplement samples comprised of alfalfa, Circu-Care, coriander, cumin, echinacea, garlic, ginger, ginkgo, horse chestnut extract, juniper berries, licorice, psyllium, saw palmetto, St. John's wort, valerian, white willow bark, and various vitamins and minerals were obtained from local supermarkets and dietary supplement companies and analyzed for fungal contamination and the presence of aerobic mesophilic bacteria. Results indicated that the highest mold and yeast counts of 5.6 × 106 colony forming units (cfu) per gram product were found in alfalfa and the lowest (1.0 × 102 cfu/g) were present in ginger supplements. Potentially toxigenic molds were found in alfalfa, coriander, echinacea, garlic, ginkgo, juniper, licorice, psyllium and St. John's wort supplements. The most common fungi were aspergilli, followed by eurotia, penicillia and yeasts. Alternaria alternata, Fusarium, Cladosporium, Rhizopus and Phoma spp. were isolated less frequently. No molds or yeasts were found in synthetic vitamins, minerals, Circu-Care and valerian. Aerobic mesophilic bacteria were isolated from all commodities tested. The highest aerobic plate count numbers (5.2 × 106-3.8 × 107 cfu/g) were recovered from alfalfa, whereas the lowest (<100-5.5 × 102 cfu/g) were found in vitamins and minerals. Practical applications With an ever-increasing population utilizing dietary supplements in order to improve and sustain health and vitality, it is essential that these products are safe for human consumption. A very critical indicator of safety is the bacteriological and mycological quality of these commodities. The results of this investigation constitute an indicator of mycological/bacteriological contamination of a variety of dietary supplements. Similar testing has not been reported for several of the studied commodities. Therefore, our findings can serve as a basis for future mycological and mycotoxin testing of dietary supplements and eventually for developing guidelines in order to achieve and maintain safe microbial levels in these products.