1. Introduction

Clostridioides (formerly Clostridium ) difficile -associated diarrhea, and urinary tract infections [5, Probiotics are “live microorganisms that when administered in adequate amounts confer a health benefit on the host” [ 1 2 ]. The benefits of consuming bacteria have been known since ancient times, when fermented milk was commonly prescribed to treat an upset stomach [ 3 ]. Today, the term “probiotic” has been defined and qualified by the World Health Organization, which put also forward guidelines to support their use. Accordingly, different probiotics have been shown to prevent or treat a wide range of health issues, including respiratory tract infections, infectious diarrhea, atopic eczema associated with cow’s milk allergy, infant colic, necrotizing enterocolitis, pouchitis, bacterial vaginosis,(formerly-associated diarrhea, and urinary tract infections [ 4 6 ].

Probiotic food products are one of the fastest growing product markets globally [ 7 ]. Currently, commercial probiotic food products contain a variety of different probiotic species and strains. Certain health benefits are common to most or all probiotic species. These effects are considered “core benefits” and include the regulation of intestinal transit, normalization of perturbed microbiota, turnover of enterocytes, competitive exclusion of pathogens, colonization resistance, and short-chain fatty acid production [ 2 ]. Meanwhile, some probiotic effects are found only among specific species of probiotics. Examples include vitamin synthesis, gut-barrier reinforcement, bile salt metabolism, enzymatic activity, and neutralization of carcinogens [ 2 ]. Lastly, certain benefits may only be found among specific strains of bacteria; this includes neurological effects, immunological effects, endocrinological effects, and the production of bioactives [ 2 ].

Therefore, probiotic food products currently in the marketplace may have the potential to offer a variety of different health benefits, depending on the specific species and strains of bacteria they contain. However, depending on in which country the products are being sold, consumers have varying degrees of information about the health benefit a probiotic product has been designed to provide.

11, The WHO has recommended that, where scientific evidence exists, strain specific probiotic health claims should be allowed to enable the linkage of a product to a specific health effect [ 8 ]. However, in the European Union, there are no approved probiotic health claims [ 9 ]. In fact, even the word “probiotic” is considered a health claim and is not permissible on food packages. In the US, products containing probiotics can state that they ”support” the body or ”maintain” general well-being (for instance, some products state; ”help support your immune system” or ”helps naturally regulate the digestive tract”) [ 10 ]. Meanwhile, in Canada, products contain a general health claim (such as “promotes a healthy gut flora”) but could provide more specific benefits depending on the species and strain(s) they contain [ 8 12 ].

To date, the majority of systematic reviews investigating probiotics have focused on the effects of different strains on a single health outcome or the effects of a single strain on different health outcomes. Furthermore, there have been no reviews focused exclusively on probiotics delivered in food formats.

This study had two objectives; first, to document the prevalence and dosage of probiotic species/strains in the Canadian food supply and, second, to review the literature investigating these species/strains in order to understand what health benefits consumers could potentially receive from the probiotic products in the marketplace.