The multidisciplinary approach to safety and toxicity assessment of microalgae-based food supplements following clinical cases of poisoning

Commercially available food supplements based on microalgae such as Spirulina (Cyanobacteria) or Chlorella (Chlorophyta) are becoming increasingly popular. Both are considered as non-toxic per se but the quality and safety of the final product depends on culturing and manufacturing conditions. This study presents two cases of human poisoning following the simultaneous use of Spirulina and Chlorella food products and a multidisciplinary approach to their evaluation: cytotoxic tests using human whole-blood in vitro and a suite of analytical screenings of over 30 elements, arsenic species and cyanotoxins: cylindrospermopsin (CYN), anatoxin-a (ANA) and three microcystin (MC) analogues. To compare metal content the Food Supplement Metal Index and Toxic Elements Contamination Index were also introduced. In all performed analyses two other commercial products were also investigated. Reported clinical symptoms of poisoning included the spreading of atopic dermatitis, nausea, dizziness, headache and fatigue. Extracts of supplements obtained from affected subjects were found to act pro-necrotically in human neutrophils, while tablets contained higher levels of several metals including Cd, Pb and Hg. All analyzed food supplements contained a significant content of Al. Neither CYN, ANA nor MC were present in any examined product. The quality of both Spirulina-based and Chlorella-based food supplements was very doubtful. The contamination problem of some commercially available microalgae-based supplements appears to be pleiotropic. The present study clearly indicates that such products should be subject to strict and routine monitoring before being registered and distributed as some of them may pose a distinct threat to human health.