New clinical research indicates that a widely used food additive, carboxymethylcellulose that affect intestinal environment of healthy persons, perturbing levels of beneficial bacteria and nutrients. These findings, published in Gastroenterology, demonstrate the need for further study of the long-term impacts of this food additive on health
The research was led by a collaborative team of scientists from Georgia State University's Institute for Biomedical Sciences, INSERM (France) and the University of Pennsylvania. Key contributions also came from researchers at Penn State University and Max Planck Institute (Germany).
Carboxymethylcellulose (CMC) is a widely used food additive, termed emulsifiers, which are added to many processed foods to enhance texture and promote shelf life. CMC has not been extensively tested in humans but has been increasingly used in processed foods since the 1960s. It had long been assumed that CMC was safe to ingest because it is eliminated in the feces without being absorbed. However, the interaction between bacteria and these non-absorbable additives in the gut makes scientists very interested in research. Experiments in mice found that CMC, and some other emulsifiers, altered gut bacteria resulting in more severe disease in a range of chronic inflammatory conditions, including colitis, metabolic syndrome and colon cancer. However, these experiments have not yet been conducted on humans in previous studies.
Experiments in mice found that CMC, and some other emulsifiers, altered gut bacteria resulting in more severe disease in a range of chronic inflammatory conditions, including colitis, metabolic syndrome and colon cancer. However, the extent to which such results are applicable to humans had not been previously investigated.
The team performed a randomized controlled-feeding study in healthy volunteers. Participants, housed at the study site, consumed an additive-free diet or an identical diet supplemented with carboxymethylcellulose (CMC). Because the diseases CMC promotes in mice take years to arise in humans, the researchers focused here on intestinal bacteria and metabolites. They found that CMC consumption changed the make-up of bacteria populating the colon, reducing select species. Furthermore, fecal samples from CMC-treated participants displayed a stark depletion of beneficial metabolites.
Lastly, the researchers performed colonoscopies on subjects at the beginning and end of the study and noticed that a subset of subjects consuming CMC displayed gut bacteria encroaching into the mucus, which has previously been observed to be a feature of inflammatory bowel diseases. Thus, while CMC consumption did not result in any disease per se in this two-week study, collectively the results support the conclusions that long-term consumption of this additive might promote chronic inflammatory diseases.
"It certainly disproves the 'it just passes through' argument used to justify the lack of clinical study on additives," said Georgia State University's Dr. Andrew Gewirtz, one of the paper's senior authors. Beyond supporting the need for further study of carboxymethyl cellulose. Lead author Dr. Benoit Chassaing, University of Paris, France, noted that such studies need to be large enough.
Source: https://www.sciencedaily.com/releases/2021/11/211130130223.htm
Translated by: Nguyen Thi Lam Doan – Dept. Biochemistry and Food Biotechnology - FST - VNUA