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Abstract

Carboxymethylcellulose (CMC) thickener/emulsifier is used commonly by the food industry to enhance texture and extend shelf life.1 Preclinical work has shown that its consumption detrimentally impacts the intestinal microbiota in a way that promotes chronic inflammation.2, 3, 4, 5 We recently reported results from the Functional Research of Emulsifiers in Humans Corrected (FRESH) study, a randomized, double-blind, controlled-feeding assay.6 After a washout period, half of the healthy recruited participants were assigned randomly to a CMC-supplemented diet (Supplementary Figure 1A). Those subjects showed significant alterations in microbiota composition and fecal metabolome relative to control subjects.6 However, the response to CMC was highly heterogenous. Specifically, 2 subjects were highly CMC sensitive in that they showed stark alterations in microbiota composition and developed microbiota encroachment, whereas other subjects were relatively insensitive to CMC (Figure 1A–C). Such CMC sensitivity was not associated with overt signs of intestinal inflammation but nonetheless might mark proneness to chronic inflammation, compelling us to better understand mechanisms that mediate CMC sensitivity.