Ubiquitous food additive alters human microbiota and intestinal
environment

Date:
November 30, 2021
Source:
Georgia State University
Summary:
New clinical research indicates that a widely used food additive,
carboxymethylcellulose, alters the intestinal environment of
healthy persons, perturbing levels of beneficial bacteria and
nutrients. These findings demonstrate the need for further study
of the long-term impacts of this food additive on health.



FULL STORY ==========================================================================
New clinical research indicates that a widely used food additive, carboxymethylcellulose, alters the 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 synthetic member of a widely used
class of food additives, 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, increasing appreciation of the health benefits provided by bacteria that normally live in the colon, and thus would
interact with non-absorbed additives, has led scientists to challenge
this assumption. 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 that are thought to normally maintain a healthy colon.

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
and type 2 diabetes.

Thus, while CMC consumption did not result in any disease per se in
this two week study, collectively the results support the conclusions
of animal studies that long-term consumption of this additive might
promote chronic inflammatory diseases. Therefore, further studies of
this additive are warranted.

"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 carboxymethylcellulose, the study "provides a
general blueprint to carefully test individual food additives in humans
in a well- controlled manner," said co-senior author Dr. James Lewis,
of the University of Pennsylvania, where the subjects were enrolled.

Lead author Dr. Benoit Chassaing, research director at INSERM, University
of Paris, France, noted that such studies need to be large enough
to account for a high degree of subject heterogeneity. "Indeed, our
results suggest that responses to CMC and likely other food additives are highly personalized and we are now designing approaches to predict which individuals might be sensitive to specific additives," Chassaing said.

This study was funded by the National Institutes of Health, the European Research Council, the Max Planck Society, the INSERM and the Kenneth
Rainin Foundation.

========================================================================== Story Source: Materials provided by Georgia_State_University. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Benoit Chassaing, Charlene Compher, Brittaney Bonhomme, Qing
Liu, Yuan
Tian, William Walters, Lisa Nessel, Clara Delaroque, Fuhua Hao,
Victoria Gershuni, Lillian Chau, Josephine Ni, Meenakshi Bewtra,
Lindsey Albenberg, Alexis Bretin, Liam McKeever, Ruth E. Ley,
Andrew D.

Patterson, Gary D. Wu, Andrew T. Gewirtz, James
D. Lewis. Randomized controlled-feeding study of dietary emulsifier
carboxymethylcellulose reveals detrimental impacts on the gut
microbiota and metabolome.

Gastroenterology, 2021; DOI: 10.1053/j.gastro.2021.11.006 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/11/211130130223.htm

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