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Category: Project

Description: Human gut microbiome research has linked imbalances in the gut microbiota with several suboptimal health conditions. Consequently, the application of dietary interventions including foods (i.e., fermented foods [FFs]) and food supplements (i.e., probiotics) that contain live microorganisms to positively impact the gut microbiota and, in turn, health, has been the subject of much attention. The benefits of consuming FFs, defined as “those made through desired microbial growth and enzymatic conversions of food components” by a ISAPP (International Scientific Association for Probiotics and Prebiotics) consensus panel, was first noted by Elie Metchnikoff in 1907, who attributed the exceptionally long life spans of eastern Europeans to the regular consumption of fermented milk. Evidence from recent studies has extended this link to multiple other FFs and health benefits. Probiotics, defined as “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host”, represent the other primary source of ingested microbes and include specific strains of lactic acid bacteria, bifidobacteria and yeasts, among others. Probiotics are distinguished from fermented food microbes in general by virtue of the greater level of evidence supporting health claims and frequently their origin (many having been sourced from a gut environment). Similar to FFs, evidence from probiotic research has established that ingestion of specific strains can provide protection against a diverse range of ailments. Despite the large body of evidence relating to the health benefits of specific probiotics and FFs, there is an absence of recommended dietary allowances (RDA) relating to the consumption of live microbes. This is partly due to an incomplete understanding of the more general health benefits imparted by ingesting live microbes. To address this, we will review the relevant scientific evidence in relation to the non-therapeutic intake of live microbes in nonpatient populations. More specifically, we will: (1) Broadly review the research involving probiotics and FFs and their improvement of health/protection provided in non-patient populations (Phase I and Phase II; see Research approach section below); (2) Identify research gaps in the existing literature relating to the intake of live microbes and concomitant positive health outcomes (Phase II); (3) Summarize and disseminate relevant research findings (Phase II); and (4) Determine the merit of undertaking full systematic reviews (Phase II). The initial scope of the review will be deliberately broad; the review process will be iterative, with research questions and search strategies being refined as the review progresses. This evidence mapping exercise will form a key step in a process towards determining the merits of recommending a level of live microbe intake that can be linked to positive health outcomes.