ALSOFOUNDINCMC (Carboxymethylcellulose)
Under StudyThickens everything — now linked to gut-barrier questions. Also listed on labels as Carboxymethylcellulose, Cellulose gum, E466, Sodium CMC.
E-number: E466
What it is
Plant cellulose — wood pulp or cotton fiber — chemically modified until it dissolves in water and thickens it. On labels it's usually the friendlier-sounding 'cellulose gum.' It's technically fiber your body can't digest, which is exactly why it's used and exactly why it's studied.
Why it's in food
It's the cheapest way to make something feel rich. CMC gives low-fat products body, stops ice cream from getting icy, keeps gluten-free dough from crumbling, and holds sauces together — often replacing fat, egg, or cream entirely.
US vs EU status
United States
GRAS and unrestricted in most foods. Then came the study that changed the conversation: a 2021 controlled feeding trial at the NIH and Georgia State — humans, not mice — found that CMC altered participants' gut bacteria, reduced beneficial metabolites, and in some people brought bacteria closer to the intestinal lining. Small trial, short duration, no regulatory action. But it's rare for an additive's file to include a human result at all.
European Union
Permitted as E466. In 2025 Europe's regulator re-evaluated the celluloses, kept them approved, and expressed the same discomfort visible elsewhere in this drawer — noting uncertainties, especially around modified celluloses and gut effects, and calling for more data. Approved, with a footnote that keeps getting longer.
Common products
- Ice cream and frozen desserts
- Gluten-free breads and baked goods
- Low-fat yogurts, dressings, and sauces
- Almond and oat milks
- Toothpaste and eye drops
- Diet and 'light' products of nearly every category
Cleaner swaps
- Full-fat versions — fat is the original thickener
- Products using guar, xanthan, or locust bean gum
- Plant milks with no stabilizers (shake before pouring)
Case note
CMC is what fat gets replaced with when fat becomes the villain — cheap body, no calories, wood pulp reborn as creaminess. Then a human trial found it shifting the bacteria in people's guts, which is more evidence than most files on this board have. Approved, unrestricted, and quietly under review on two continents.
FAQ
What makes the 2021 study different from the mouse research?
It was human. Participants ate a CMC-containing diet under controlled conditions, and researchers measured real shifts in gut bacteria, a drop in beneficial short-chain fatty acids, and bacteria encroaching on the intestinal lining in some people. It was small and short-term, and it proved no disease. But most additive concerns never get past rodents — this one did.
Isn't cellulose gum just fiber?
Chemically modified fiber, and the modification is the whole question. Natural cellulose passes through inertly; CMC is engineered to dissolve and thicken, which changes how it interacts with the mucus layer and the bacteria living in it. 'It's just fiber' is the industry's shortest defense and the one the 2021 trial complicated.
Why is it in gluten-free bread?
Because gluten is a structural protein and its absence leaves dough with nothing to hold it together. CMC mimics that stretch and moisture retention, which is why the gluten-free aisle is one of the most additive-dense sections in the store. People eating for a genuine medical reason often end up with the longest ingredient lists — an irony worth naming.
How do I spot it?
Look for 'cellulose gum,' 'carboxymethylcellulose,' or CMC — the first is the most common and the least alarming-sounding. Practical rule: the lower the fat and the longer the shelf life, the more likely a thickener is standing in for something that used to be food.
How the FDA decides what reaches your table and your medicine cabinet — and how it learned to decide.
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