Probiotic research priorities for the healthy adult population: A review on the health benefits of <i>Lactobacillus rhamnosus</i> GG and <i>Bifidobacterium animalis</i> subspecies <i>lactis</i> BB-12

A diluted distribution of research efforts hampers probiotic innovation and curtails potential health benefits for the consumer market. Research priorities have been postulated to aid strategic planning, but it remains to be determined how probiotic strains currently pertain to these priorities. We therefore set out to review how probiotic research priorities are currently met by the two best-documented strains, Lactobacillus rhamnosus GG (LGG) and Bifidobacterium animalis subspecies lactis BB-12 (BB-12), focusing on the needs of the healthy adult population. A literature search was conducted to retrieve clinical studies in adults, reporting on in vivo effects of BB-12, LGG, or LGG + BB-12. A framework of studies was created, with a separate emphasis on the potential of probiotics to prevent disease in healthy adults. A total of 76 papers were reviewed. Current evidence indicates that LGG and BB-12 supplementation may promote human health and support the daily wellness of consumers, although most (earlier) trials do not meet the stringent standards required for scientific substantiation of a health claim in Europe. To advance innovation and respond to unmet health needs, it is crucial that well-designed, appropriately scaled studies build on top of promising data, specifically in areas where strong associations are apparent.