Background – New species and more specific strains of probiotic bacteria are constantly being sought for novel probiotic products. Their safety cannot be assumed. Prior to incorporating novel strains into products a careful evaluation of their efficacy is required and an assessment made as to whether they share the safety status of traditional food-grade organisms. Probiotic products which claim specific nutritional, functional or therapeutic characteristics blur the boundaries between what is a food, a diet supplement or a medicine, posing challenges for regulators.
Objective – To report on the adequacy of contemporary studies to characterize and substantiate probiotic safety. Design – Probiotic studies were examined in relation to the guidelines proposed for safety of probiotics.
Outcomes – Evidence for the safety and efficacy of probiotic organisms has until recently been largely anecdotal or based on relatively little, and often poorly designed research. Food organisms intrinsic to the production of traditional foods have been arbitrarily classified as safe in the absence of scientific criteria, partly because they exist as normal commensal flora, and because of their presence for generations presumably without adverse effect.
Many bacteria are being tested to find a putative probiotic, yielding conflicting data, sometimes for the same organism. Comparisons between studies and organisms cannot be readily made because of non-standardised dosing procedures, particularly for the number of bacteria and the duration of dosing. Information is not readily available on the equivalence or comparability of formulations in different probiotic preparations. Intake data are not generally available for those countries where products are used.
Conclusions – The demonstration of efficacy in probiotics offers vast opportunities to develop human and veterinary products. A new probiotic culture must be at least as safe as its conventional counterparts. There is vigorous debate on what constitutes appropriate safety testing for novel strains proposed for human consumption. Conventional toxicology and safety evaluation is of limited value in assessing the safety of probiotic bacteria. The addition of novel bacterial strains to foods and therapeutic products requires reconsideration of safety assessment procedures.