Not all bacteria are harmful to the body. Certain bacteria, termed probiotics, may work with the body and have a positive influence – potential effects include maintaining optimal intestinal flora, lower colonic pH, improve digestion and support of the immune system. There is no one definition of probiotics, but the Food and Agriculture Organization (FAO) of the World Health Organization (WHO) has defined probiotics as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. The nature of the host and the level of benefit impacts how a probiotic is regulated in the U.S.: a probiotic added to food is a food ingredient and is therefore categorized as a food; a probiotic for animal use is a direct-fed microbial and is therefore a feed ingredient, while a probiotic administered to treat, prevent, cure or mitigate disease, or to competitively inhibit another organism would be regulated as a drug. Essentially, the intended use of the probiotic and the associated claims will drive how the probiotic is regulated.
In the U.S., there is no legal definition of the term “probiotic” and so there is no regulatory framework that companies can utilize specifically for probiotic ingredients or claims. However, basic tenants for food and dietary supplements address certain core issues: an ingredient, whether for food or for dietary supplements, must provide the intended function throughout the proposed shelf life of the product. For probiotic ingredients this means that the microorganism must be viable for the shelf life of the final product. The shelf-life studies must be conducted under conditions that mimic storage and retail conditions, such as whether the probiotic is to be refrigerated, stored at room temperature, or away from sunlight. In addition to viability, the probiotic must have been shown to be able to perform its intended effect. To meet U.S. regulations, a probiotic to be added to food must be approved as a food additive through a food additive petition (FAP) or must be determined to be generally recognized as safe (GRAS). Although a probiotic is intended to confer a health benefit to the host, the FDA (for a food additive) or a GRAS panel of experts should only evaluate the safety of the intended use (typically thought of as the amount of ingredient consumed on a daily basis); benefits are not evaluated within a GRAS or FAP. The general aspects of safety for a food ingredient also apply to a probiotic (e.g., manufacturing process controls, specifications, stability) and extend to aspects specific for a microorganism, which include taxonomy, pathogenicity, potential toxin production and the potential for the probiotic to become antibiotic resistant.
The historical stance of the U.S. Center of Veterinary Medicine (CVM) that evaluates the safety of food and drugs for animals was that use of the term “probiotic” on the label of a product automatically made the product a drug. However, in the last couple of years the term “probiotic” has had broader use, even in CVM guidance documents so that now a probiotic used in animal feed can be regulated either as a food or a drug, depending on the product claim(s). A probiotic labeled to cure, mitigate, treat or prevent disease is considered by CVM to be a new animal drug. In addition, a probiotic with claims to affect the structure or function of the body is also considered a new animal drug.
Because the intended use of a probiotic impacts whether the ingredient is regulated as a food ingredient or a drug, an understanding of the types of claims that may be made for probiotics is necessary. Claims concerning the effect of a substance on the structure or function of the body may be made for dietary supplements and foods (provided they are truthful, not misleading, and are substantiated with scientific evidence). However, the claims must be carefully worded: the claim that a food or probiotic “helps maintain intestinal flora” is an appropriate structure/function claim (does not imply an effect on disease), but the claim “helps individuals using antibiotics to maintain normal intestinal flora” is an implied drug claim (i.e., an implicit claim that the probiotic will prevent or mitigate disease). As an example, Dannon’s Activia brand of yogurt contains the probiotic Bifidobacterium lactis, claimed to “work in your gut to help regulate your digestive system by helping with slow intestinal transit.” The Federal Trade Commission (FTC) won a settlement with Dannon for the company to qualify the statement clarifying that “any statements about benefits for digestion or the immune system are based on European studies involving three servings a day of yogurt.” However, Dannon cannot claim its yogurt products can reduce the chance of getting a cold or flu unless that claim is approved as a health claim by FDA. A health claim stating that a food ingredient may “reduce the risk” of a disease or health-related condition may be made only after FDA authorizes the claim after review of a petition for the claim, either under “significant scientific agreement” or authorized with qualifying statements on the amount of scientific evidence for the claim.
Other countries may view claims for probiotics differently than the U.S. In Ireland, authorities have taken a literal view of the E.U. health claims evaluation and decided that because no probiotic has yet won a health claim under the E.U. nutrition and health claim regulation, even ingredient descriptions using the term “probiotic” are banned in marketing and promotional materials provided to consumers. The authorities have stated that the term “probiotic” implies that the substance may be beneficial to consumers, because etymologically, the term appears to be a composite of the Latin preposition pro (“for”) and the Greek adjective βιωτικός (biotic), the latter deriving from the noun βίος (bios, “life”); therefore – “for life”. The E.U. regulation on health claims states that anything that suggests or implies a relationship between food and health can be considered to be a health claim. Therefore, this would include “probiotic” and terms like “live” or “active” which also imply a probiotic function. However, the name of the individual microorganism culture may be stated on the label or marketing, as the name itself does not imply a healthful effect.
Probiotics may confer benefits to the host, but the associated claims and intended effect may push what was once considered a food or dietary supplement ingredient into drug status. Safety is the focus of any regulatory path to be able to add probiotics to food or dietary supplements, but the intended use indicates whether the probiotic is a food or a drug.
 “Prebiotics” on the other hand are those substances, such as fiber, that encourage the growth of probiotic organisms.
 65 Federal Register 2000; 1000:1029