Dietary Exposures to Common Emulsifiers and Their Impact on the Gut Microbiota: Is There a Cause for Concern?

Emulsifiers are commonly used in food processing for the technological purpose of altering the flavor or to improve the texture of foods. Due to their ubiquity, these substances are consumed daily at low levels in the human diet. Recently published in vitro and in vivo studies suggest dietary exposure to emulsifiers modulate the gut microbiota and contribute to the increasing prevalence of metabolic disease. A literature search was conducted which identified eight studies investigating the interaction of sodium carboxymethyl cellulose, polysorbate 80, gum arabic, carrageenan, and arabinogalactan with the gut microbiota in murine and in vitro models. Numerous inconsistent changes in various phyla and genera were identified. These studies were conducted at high doses that have no relevance to the current dietary levels consumed in the United States. Subtle changes in gut microbiota composition as a toxicological endpoint is not supported by established internationally recognized toxicology testing guidelines. Therefore, the results of these studies are difficult to interpret and extrapolate to humans and are not supported by previous safety conclusions of international food safety authorities. The current understanding of the gut microbiota is that the structure is highly dynamic and is heavily influenced by the diet. Thus, the results of these studies may not necessarily suggest a safety concern, but rather reflect an adaptive response of the gut microbiota to an external stressor. Future research will need to further elucidate the mechanisms of metabolic disease in rodents and humans and establish clinically relevant and reliable endpoints to assess changes in gut microflora.