Carboxymethylcellulose in Diet Adversely Affects Gut Microbiota and Metabolome

A plate of tasty moist chocolate brownies cut into squares sitting on a table.
Investigators assessed the effects of dietary consumption of the emulsifier carboxymethylcellulose on microbiome composition and intestinal health.

The addition of the dietary emulsifier carboxymethylcellulose (CMC) to a healthy additive-free diet may increase postprandial abdominal discomfort and affect intestinal microbiota composition, according to a study in Gastroenterology.

The double-blind, randomized, controlled-feeding study enrolled healthy volunteers aged 18 to 60 years from April 12, 2018, to January 16, 2019. Participants adhered to an emulsifier-free diet (n=9; mean age, 41.11±12.72 years; 6 women) or to an identical diet enriched with 15 grams per day of CMC (n =7; mean age, 35.24±11.28 years; 3 women) for 11 days.

For the first 3 days of the study, the participants were outpatients, followed by 11 days as inpatients. From days 4 to 14, all participants consumed 3 servings of brownies and 3 servings of sorbet that either lacked or contained 2.5 g of CMC per serving.

The investigators found that CMC consumption was associated with a modestly significant increase in postprandial abdominal pain (P =.019). Participants who consumed CMC had greater changes in microbiota composition during the intervention period, as principal coordinate analysis plots revealed treatment-based clustering after 10 days of CMC consumption (Permanova day 0, P =.928; day 9, P =.228; day 14, P =.002).

In participants who consumed CMC, fecal metabolomes were depleted in a number of microbiota-related metabolites, including short-chain fatty acids and essential amino acids. These changes were clearly evident within 3 days and remained throughout the period of CMC consumption; these changes had resolved when the participants were re-evaluated on day 48.

Although bacterial epithelial distance did not change on average in either group, 2 participants in the CMC group had a decrease in this distance, as bacteria were very close in proximity to the epithelium after CMC exposure. The 2 participants also had significantly greater relative changes in microbiota composition following CMC consumption compared with others in the CMC group (group effect, P =.004).

The researchers noted that their study was focused on the short-term effects of CMC consumption, especially on the gut microbiome, and additional studies are needed to evaluate the long-term effects.

“These results support the notion that the broad use of CMC in processed foods may be contributing to increased prevalence of an array of chronic inflammatory diseases by altering the gut microbiome and metabolome,” the study authors commented.


Chassaing B, Compher C, Bonhomme B, et al. Randomized controlled-feeding study of dietary emulsifier carboxymethylcellulose reveals detrimental impacts on the gut microbiota and metabolome. Gastroenterol. Published online November 11, 2021. doi: 10.1053/j.gastro.2021.11.006