Health & Wellbeing

Human trial finds common food additive alters gut microbiome

Human trial finds common food additive alters gut microbiome
New research looked at how a common food additive used as an emulsifier influences the gut microbiome
New research looked at how a common food additive used as an emulsifier influences the gut microbiome
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New research looked at how a common food additive used as an emulsifier influences the gut microbiome
New research looked at how a common food additive used as an emulsifier influences the gut microbiome

A first-of-its-kind study investigating the effects of a common food additive on human gut bacteria has found the emulsifier carboxymethylcellulose can alter the quality and composition of the microbiome and potentially increase a person’s risk of chronic intestinal inflammation.

Many food additives approved for human consumption across the 20th century were generally understood to be safe based on research showing they mostly pass through our intestines unabsorbed and are eliminated in feces. However, our growing understanding into the relationship between the vast population of bacteria in the gut and our general health has led many researchers to reevaluate the effects of these chemicals previously thought to be harmless.

Titanium dioxide, for example, was used for decades as a white food coloring agent. Long thought to be essentially non-toxic it was only recently that scientists discovered the chemical's profound effect on the gut microbiome, particularly when delivered in the form of nanoparticles. Many countries in the world have now banned the additive from foods.

Carboxymethylcellulose (CMC) was originally approved as safe to use in foods in the 1960s. It is commonly used as a thickening agent or emulsifier, and listed under E numbers 466 or 469. It is also sometimes referred to as "cellulose gum" and added to foods as "dietary fiber."

Recent lab and animal studies have indicated CMC may perturb the gut microbiome and promote the development of inflammatory disease. But, the effect of CMC on animals doesn’t necessarily mean it is harmful to humans. So this new research set out to systematically test how CMC influences the human gut microbiome.

Sixteen subjects were recruited for what is known as a controlled feeding study. For 11 days the participants were admitted as inpatients into a controlled hospital environment and either received a diet supplemented with CMC or a diet free of CMC.

At the end of the study notable changes were detected in the gut bacteria populations of the CMC group compared to the control fed the same diet but without CMC. Alongside bacterial changes, alterations to bacterial metabolites, including reductions in short-chain fatty acids and free amino acids, were detected.

“We observed stark changes in gut microbiota, fecal metabolome and, in a subset of the participants, encroachment of microbiota upon the gut epithelium,” the researchers write in the newly published study. “The predominant changes in the fecal metabolome upon CMC feeding was loss of purportedly beneficial metabolites. We envision this change likely reflected loss of key taxa and/or general disruption of microbial community homeostasis.”

The researchers are clear to note that the short duration of the study means it is impossible to directly link CMC consumption with the development of chronic gut inflammation. However, it is noted that all of the changes detected in the short study do correlate with biomarkers previously associated with inflammatory diseases.

"It certainly disproves the 'it just passes through' argument used to justify the lack of clinical study on additives," adds Andrew Gewirtz, senior author on the study.

Moving forward, the study indicates CMC levels can be effectively measured in feces. This offers a future blueprint for studying the food additive in populations with chronic inflammatory diseases.

It is also noted that high levels of CMC were given to the study participants (15 grams per day). This is higher than most people would naturally consume but the study indicates this could, “approximate the total amount of emulsifier consumption by persons whose diets are largely comprised of highly processed foods that contain numerous emulsifiers.”

Ultimately, the researchers hypothesize CMC could be playing some kind of role in the rise of chronic gut inflammatory disease over the past few decades. Of course, this singular food additive is not suspected to be the sole cause of inflammatory disease, but instead it may contribute to a person’s overall risk of developing gut inflammation.

“That the post-mid-20th century increased incidence of chronic inflammatory diseases has been roughly paralleled by increased consumption of highly processed foods has long suggested the possibility that some components of such foods promote inflammation,” the researchers conclude in the study. “Appreciation of the role of the intestinal microbiota in driving inflammation led to interest in food additives capable of perturbing the host-microbiota relationship.”

The new study was published in the journal Gastroenterology.

Source: Georgia State University

When it comes to this kind of research, it is worth noting that there are differing needs pulling in opposite directions
The desire to improve peoples’ diets and their health will almost certainly point to at least some of the changes in foods that we have been consuming in the past six / seven decades; but those additives have also (partially) led to food prices that are historically low.
Also, many subsequent health issues are hidden because they happen over time and do not occur in a vacuum
We are also subject to advice from ‘experts’ who spent fifty plus years telling everyone not to eat eggs because of their cholesterol content, and who only recently and very reluctantly admitted that they were wrong about that particular food’s effect on humans’ blood cholesterol levels.
This will be a long fight
Voice of Reason
As an environmental microbiologist, it is not surprising to find that added fiber influences gut microflora. What's missing in this report, however, is any mention of how much CMC as added to the study diet and how that might relate to normal dietary intake. It's not unusual for unreasonably high doses to be used to show effect. In my view, any report that fails to discuss dosage is suspect of exaggeration. The anti-BPA movement is a good example (an ingredient in some plastics). High doses in lab animals showed pseudo-hormonal effects, but despite years of multiple studies in humans and FDA meta-analyses, no impact has been demonstrated from human exposure at actual intake levels.
All health issues that develop over the long term might be hidden to non-scientists or to people who don't make an attempt to manage their health. But for those who are aware of consequences, this information is just another of Rich's spot-on synopsis of the data. What occurs in a vacuum is Science - as our technology improves our testing equipment, we can analyze processes step by step and recognize previous wrong conclusions. Since 1990's the focus on necessary fatty acids and cholesterol found in rich source foods (like eggs) has been reevaluated. The experts who advised against egg rich diets were not wrong - but the transformation from focus on FATTY ACIDS as well as cholesterol to a more complete diet (since the 1990's) hasn't changed the food industry which has invested in years of food, additive, and flavoring research to keep money makers on the shelves. This fight will be only as long as consumers have no choice in the matter of what they eat - and why!

No, high sugar, low fat foods are not healthy any more than an egg rich diet is healthy - I don't care what statin you take! But until food conglomerates pivot to actually producing food "closer to the field" with fewer enhancements and preservatives, newly discovered untoward effects will continue - and we in medicine will continue digging deeper into those untoward effects. It is continuous education that makes science and medicine improve - not fear or predictions.
For a long time we have been told how all the food additives and preservatives are safe. Unfortunately most of the studies that deemed them safe were of short duration, with no focus on the long term impact. Only recently have they begun to study and evaluate the longer term impacts. What most people don't realize is that most of these chemicals and additives were developed not for the health and well being of the consumer but for the profitability of the aggro business. I think it is high time that all of these additives be reexamined properly and banned if not found to be 100% safe.
Mark T.
Cellulose mainly comes from wood pulp and cotton. Carboxymethyl cellulose is a cellulose chemical derivative. The first thing the food industry thinks when it looks at something cheap and inedible to humans is can they put it in our food or at least chemically modify it and put it in their products and sell it as food. Given those impure motivations, it is hardly surprising chemically modified cellulose is bad for you. As a rule of thumb, you can safely assume the chemically modified inedible substances should not be in your food.
It is Ok (actually, of course, not Ok) a new suspect, CMC has appeared among those agents causing inflammation of the gut. As a common citizen I miss at least a hint from the study that what remedy a consumer can find to cure the damage (i.e. the inflammation) until this additive gets eliminated from food products by legal regulation.