Cellulose gum
A plant-derived thickener that gives foods a gel-like texture. Animal studies link it to gut inflammation at high doses.
Animal studies at high doses show CMC alters gut bacteria and promotes low-grade intestinal inflammation. Human relevance at normal food doses is not yet established.
What is it?
Cellulose gum is the common name for sodium carboxymethylcellulose (CMC). It is made by chemically treating plant cellulose (usually from wood pulp or cotton) with chloroacetic acid to attach carboxymethyl groups. The result is a white powder that dissolves in water to form a thick, stable gel. It is not absorbed by the body and passes through the digestive tract.
What does it do?
CMC dissolves in water and greatly increases the viscosity of liquids, giving foods a smooth, thick, gel-like consistency. It stabilises emulsions (keeping oil and water from separating), prevents ice crystals forming in frozen foods, and stops sauces from separating on standing. It also acts as a bulking agent in reduced-fat products, mimicking the mouthfeel that fat would otherwise provide.
Where you will see it
Ice cream and frozen desserts, reduced-fat salad dressings, sauces and gravies, gluten-free bread (improves dough structure), soft drinks, cream cheese and processed cheese spreads, toothpaste (not a food use but very common), and diet or meal-replacement products. On a UK food label it appears as E466, cellulose gum, or sodium carboxymethylcellulose.
What the science says
Gut microbiome and intestinal inflammation in animal studies
Two mouse studies by Chassaing and colleagues found that CMC at doses equivalent to a high human intake disrupted the protective mucus layer of the gut, shifted the composition of gut bacteria, and promoted chronic low-grade inflammation. One of those studies linked this gut disruption to features resembling metabolic syndrome, including weight gain and raised blood sugar. These findings were in rodents given relatively large doses in their drinking water; whether the amounts people consume from food cause the same effects is unknown.
Dietary emulsifiers including CMC at 1% in drinking water altered gut microbiota composition, reduced mucus layer thickness, and induced low-grade intestinal inflammation and metabolic syndrome features in mice.
CMC consumption in mice promoted encroachment of bacteria into the normally sterile mucus layer and increased markers of intestinal inflammation, effects not seen in germ-free animals, indicating a microbiome-dependent mechanism.
Human pilot trial on gut microbiome
A small human dietary intervention study by the same research group tested CMC in healthy adults. It reported that some participants showed altered microbiome composition and reduced bacterial diversity after consuming CMC, though the study was very small and the findings were not consistent across all participants. This remains a preliminary signal, not a confirmed human health effect.
A small randomised crossover trial found CMC consumption altered gut microbiota composition in some but not all healthy adult participants, with no consistent change in inflammation markers.
EFSA re-evaluation: no numerical ADI, data gaps noted
EFSA reviewed all cellulose-derived food additives including E466 in 2018 and concluded there was no need to set a numerical ADI for the general population. A 2022 follow-up specifically examined use in infant formula for babies under 16 weeks and found no data had been submitted, though manufacturers stated E466 is not used in that category. EFSA recommended tightening limits on trace contaminants (arsenic, lead, cadmium) in CMC specifications.
No numerical ADI was set for E466; the Panel concluded there was no safety concern at reported use levels for the general population. An indicative exposure value of approximately 660 to 900mg/kg body weight per day was noted.
The 2022 EFSA follow-up found no biological or toxicological data had been submitted for E466 use in foods for infants below 16 weeks; since manufacturers declared it is not used in that category, no safety assessment for that age group was performed.
Where it stands with the regulators
Who should be careful
No mandatory allergen declaration applies. People with irritable bowel syndrome or inflammatory bowel conditions may wish to monitor their response to foods containing CMC, given the animal and preliminary human data on gut disruption, though there is no clinical guidance recommending avoidance. Look for E466, cellulose gum, or sodium carboxymethylcellulose on ingredient lists.
The honest read
CMC has been used in food for decades and is authorised in the UK and EU with no numerical safety limit set, reflecting a long track record at typical food doses. The reason concern=true here is a specific body of animal research, plus a small human pilot, suggesting that CMC can disrupt the gut mucus layer and alter gut bacteria. The animal doses were high relative to what most people consume from food, and the human trial was too small to draw firm conclusions. This is a live area of research, not a settled hazard. The honest read is that the animal signal is real and biologically plausible, the human evidence is preliminary, and the question of whether normal dietary intake causes harm has not been answered.
Related additives
Common questions
Is E466 banned in the UK?
No. E466 is an approved food additive in the UK under the assimilated EU Regulation 1333/2008, and it remains on the UK FSA approved-additives list.
Does E466 affect gut health?
Animal studies have found that CMC at relatively high doses disrupts the gut mucus layer and alters gut bacteria, leading to intestinal inflammation. A small human pilot trial found some microbiome changes in some participants. Whether the amounts present in everyday food cause the same effects in people is not yet known.
What foods contain E466?
Ice cream, reduced-fat salad dressings, processed cheeses, gluten-free breads, sauces, soft drinks, and meal-replacement products are among the most common sources. It appears on labels as E466, cellulose gum, or sodium carboxymethylcellulose.
Is E466 vegan?
Yes. CMC is derived from plant cellulose (wood pulp or cotton) and contains no animal-derived ingredients.
Sources
- EFSA re-evaluation of celluloses E460(i) to E469 as food additives (2018)
- EFSA 2022 follow-up opinion on E466 in infant foods below 16 weeks, EFSA Journal
- Chassaing B et al. Dietary emulsifiers impact the mouse gut microbiota promoting colitis and metabolic syndrome. Nature, 2015
- Chassaing B et al. Randomized controlled-feeding study of dietary emulsifier carboxymethylcellulose reveals detrimental impacts on the gut microbiota and metabolome. Gastroenterology, 2022
- UK FSA approved additives and E numbers
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