Safety of probiotics.

New species and more specific strains of probiotic bacteria are constantly being sought for novel probiotic products. Prior to the incorporation of novel strains into food or therapeutic products a careful evaluation of their efficacy is required and an assessment made as to whether they share the safety status of traditional food organisms. Food organisms intrinsic to the production of traditional foods have been arbitrarily classified as safe in the absence of scientific criteria. Evidence for the safety and efficacy of probiotics has until recently been largely anecdotal or based on relatively little, and often poorly designed research. The demonstration of efficacy in probiotics offers vast opportunities for the development of human and veterinary products. The introduction of a new probiotic culture demands that it be at least as safe as its conventional counterparts. 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-standardized dosing procedures. Information is not readily available on the equivalence of formulations for different probiotic preparations. There is vigorous debate on what constitutes appropriate safety testing for novel probiotic strains proposed for human consumption. Conventional toxicology and safety evaluation is of limited value in assessing the safety of probiotics. The addition of novel bacterial strains to foods and therapeutic products requires reconsideration of the procedures for safety assessment. This paper provides an overview of these issues.