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

Abstract

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.

Nanoemulsions for health, food, and cosmetics: a review

“…Increasing rate of consumption of processed foods and beverages has led to increased use of food additives and processing aids such as emulsifiers, which are meant to enhance the texture, flavor, stability and shelf-life of foods (Roca-Saavedra et al 2018;Vo et al 2019). The hydrophilic and hydrophobic molecular groups in emulsifiers contribute to immiscibility of the formulated liquids, which then lead to much enhanced homogeneity and stability in the final products as found in butter, mayonnaise, dressings, chocolates, ketchups and yogurts (Shah et al 2017;Vo et al 2019). Emulsifiers have been estimated to constitute more than 70% of the world's approved food ingredients (Shah et al 2017), necessitating the importance and use of nanosized emulsifiers in this century.…”

The Importance of the Microbiome in Critically Ill Patients: Role of Nutrition

“…Besides, many dietary ingredients, different from macronutrients, can affect the gut microbiome. Enteral diets may contain diverse synthetic dietary emulsifiers and preservatives, including carboxymethyl cellulose, soy lecithin, gum arabic, soy polysaccharide, and various glycerol derivatives that have been linked to intestinal dysbiosis [70]. In this regard, Chassaing et al [71], found that two commonly used dietary emulsifiers, carboxymethyl cellulose and polysorbate-80, caused microbial instability of the gut microbiome in mice, characterized by an increase in the Verrucomicrobia and Proteobacteria phyla.…”

Food additives: Assessing the impact of exposure to permitted emulsifiers on bowel and metabolic health – introducing the FADiets study

“…Likewise, in mice, ingestion of drinking water containing the emulsifier/thickener carboxymethylcellulose (a 2% w/v solution for 3 weeks) induced changes to their intestinal structure and promoted leukocyte migration to the intestinal lumen (Swidsinski et al 2009). Exposure to carboxymethylcellulose in this study though [ $ 66 mg/kg bodyweight/day based on a 30g mouse (Vo et al 2019)] is 2-3 times higher than the estimated mean daily exposure seen in the US population (Shah et al 2017). Potential effects of food additives on the gut microbiome have generally been overlooked; however, emerging evidence, mainly from animal studies, suggests that several common food additives, not just emulsifiers, can induce microbiotamediated adverse effects (see Table 3).…”

“…Benoit Chassaing and colleagues undertook in vivo animal studies where ingestion by mice of polysorbate 80 at higher concentrations [up to 1% v/v in their drinking water for 13 weeks; about equivalent to 2500 mg/kg bodyweight/day (see Vo et al )] caused depletion of the mucus barrier, allowing for closer apposition between luminal bacteria and the intestinal epithelium. More severe inflammation was observed in colitis‐susceptible interleukin‐10 knockout ( Il10 ‐/‐ ) mice (Chassaing et al ).…”

“…However, to date these effects have not been confirmed in humans. Comparison with estimated dietary exposure to polysorbate 80 and carboxymethylcellulose suggests that researchers conducting these animal studies have used far higher levels of exposure than would typically be seen for the US population (Shah et al ; Vo et al ). Using maximum‐use levels obtained from publicly available sources, it has been estimated that lecithin and mono‐ and diglycerides have the highest mean exposures among consumers (between 60 and 80 mg/kg bodyweight/day), whereas the exposure to carboxymethylcellulose is half to one‐third less, and the exposure to polysorbate 80 is approximately half that of carboxymethylcellulose, with no additional evidence available to suggest that levels have increased since 2010 (Shah et al ).…”