Emulsifiers are in many of the processed foods we buy. They are added to the foods to enhance texture and extend shelf life. Animal and human studies find that some emulsifiers (e.g., soy lecithin, carrageenan, polysorbate-80) can promote gut inflammation and alter the gut microbiome in a negative or harmful way. Recent research adds to this list the common emulsifier carboxymethylcellulose (CMC), also known as cellulose gum.
A small study randomly assigned 16 healthy adults to either an emulsifier-free diet or an identical diet with added 15 g per day of CMC for 11 days. No one knew what diet they were eating, and for those 11 days the participants were inpatient - thus no chance for cheating or altering the diet. Extensive testing (even biopsies on day 1 and 11!) was done before, during, and after the study. The Univ. of Pennsylvania researchers found that CMC resulted in several harmful changes, including a negative effect on the gut microbiome (microbial community of bacteria, viruses, fungi).
Results: The researchers found that CMC increased abdominal discomfort after meals, disturbed the gut microbial community and reduced its diversity (not good!). It resulted in reductions of short-chain fatty acids and free amino acids (thus impacted how nutrients are absorbed). One of the beneficial microbes associated with good health, and that was reduced in number was Faecalibacterium prausnitzii.
Two of the subjects who had CMC in their foods had increased microbial "encroachment into the normally sterile inner mucus layer" of the gut, which is a central feature of chronic inflammation diseases (e.g., IBD, type 2 diabetes). They also had large "alterations in microbiota composition". This means that there is variation in how people respond to the emulsifier CMC, with some people more sensitive than others.
The scary part is that the intestinal changes happened after just 11 days with a daily intake of 15 g of CMC - a dose that is approximately the total emulsifier consumption for a person whose diet is largely highly processed food. Yes, that is many of us eating a Western style diet (e.g., highly processed foods, and low in fiber, fresh fruits, vegetables, and whole grains). The scientists believe that long-term consumption of emulsifiers, because they result in gut microbial disruption and inflammation, are contributing to chronic diseases.
Bottom line: Read the ingredients list on food labels. Try to avoid foods that have ingredients listed that you wouldn't normally have in your kitchen. That means soy lecithin, CMC, cellulose gum, carrageenan, artificial colors. Even "natural flavors" (which are laboratory concoctions) should be avoided as much as possible.
From Medical Xpress: Ubiquitous food additive alters human microbiota and intestinal environment
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.