Carboxymethylcellulose (Cellulose Gum)
Last reviewed October 18, 2026 · Evidence strength: Limited · How we grade evidence
In plain words: Cellulose gum (CMC) is a thickener made from plant fiber. It changed gut bacteria in mice and in one small human study. Large population studies link it to slightly higher heart risk, but that doesn't prove cause, and a recent trial in people with Crohn's disease found no harm from emulsifiers. Eating more whole, less-processed foods naturally cuts it.
Also listed on labels as: Carboxymethylcellulose, Cellulose gum, Sodium carboxymethylcellulose, CMC, E466
What is it, and why is it in food?
CMC is cellulose (the fiber in plant cell walls) that's been chemically modified so it dissolves in water. It thickens, keeps ice crystals small and keeps baked goods moist. It's in ice cream, snack cakes, frosting, sauces, gluten-free baking and many low-fat products.
What does the science say?
| The popular claim | "Emulsifiers and gums damage the gut lining and microbiome." (Often said about additives like CMC; widely attributed to Gary Brecka, but we couldn't verify it in his own words.) |
| Our verdict on that claim | Partly supported |
| Evidence strength | Limited: strong in mice; one small, short human trial; population studies show small links. |
| Kinds of studies | Mouse studies, small randomized feeding trial, population studies, trial in Crohn's disease |
- Mice: In a 2015 study, mice given CMC or polysorbate 80 in water developed gut bacteria changes, low-grade inflammation and signs of metabolic syndrome.1
- People: In a small 2022 feeding trial (7 people on CMC vs 9 on a control diet for 11 days), 15 grams of CMC a day lowered gut-bacteria diversity, caused mild belly discomfort, and in 2 people let bacteria move into the protective mucus layer.2
- Population studies: In NutriNet-Santé, higher CMC intake was linked with slightly higher heart disease risk (3% to 4% higher per step up in intake).3
- Crohn's disease: A 2025 double-blind feeding trial found no difference in disease activity between high- and low-emulsifier healthy diets over 4 weeks. The authors said advice to avoid emulsifiers in active Crohn's "is not supported."4
What do regulators say?
- US and EU: permitted (E466). Our research didn't re-read the latest EU review of CMC.
Who should be careful?
- People with IBD or gut symptoms may want to try limiting CMC and other emulsifiers, while knowing the Crohn's trial was reassuring.
- Most families don't need to avoid it. Fewer ultra-processed foods is the bigger, easier win.
How common is it in US foods?
In our check of USDA's Branded Foods database, 16,104 of 439,966 US packaged foods with an ingredient list name carboxymethylcellulose or cellulose gum (about 3.7%, or roughly 1 in 27).5 It shows up most often in: ice cream & frozen yogurt (4,670); cakes, cupcakes, snack cakes (2,670); cookies & biscuits (622); mexican dinner mixes (532); breads & buns (493). These are label records companies sent to USDA, mostly in 2021 to 2023, so some products have changed since. Counts come from a text match of ingredient lists and are approximate.
Swaps and tips for families
- Choose ice cream with a short ingredient list.
- Homemade or bakery cake usually skips gums.
- Note the 2022 trial used 15 grams a day, far more than most people eat.
Beyond the plate: related non-food exposures
Cellulose gums are also common in medicines, vitamins, toothpaste and cosmetics (our research didn't evaluate these uses separately).
Frequently asked questions
Is cellulose gum bad for you?
It's allowed and probably fine in small amounts for most people. A small human trial found it changed gut bacteria at high doses, and population studies show slight links with heart risk, so limiting it is reasonable.
Is cellulose gum natural?
It starts as plant fiber but is chemically modified, so it's a processed additive.
Does CMC cause leaky gut?
Not shown in people. In 2 of 7 people in a small trial, bacteria moved closer to the gut lining, which is an early clue, not proof.
Related guides
Sources
Every source below was checked against PubMed, the publisher or the official page by our research team in October 2026.
- Dietary emulsifiers impact the mouse gut microbiota promoting colitis and metabolic syndrome. Nature, 2015. PubMed 25731162 · doi:10.1038/nature14232
- Randomized Controlled-Feeding Study of Dietary Emulsifier Carboxymethylcellulose Reveals Detrimental Impacts on the Gut Microbiota and Metabolome. Gastroenterology, 2022. PubMed 34774538 · doi:10.1053/j.gastro.2021.11.006
- Food additive emulsifiers and risk of cardiovascular disease in the NutriNet-Santé cohort. BMJ, 2023. PubMed 37673430 · doi:10.1136/bmj-2023-076058
- Clinical Trial: The Effects of Emulsifiers in the Food Supply on Disease Activity in Crohn's Disease: An Exploratory Double-Blinded Randomised Feeding Trial. Aliment Pharmacol Ther, 2025. PubMed 39967287 · doi:10.1111/apt.70041
- FoodData Central, Branded Foods dataset (release 2026-04-30). U.S. Department of Agriculture, Agricultural Research Service, 2026. Link
- Food additive emulsifiers and the risk of type 2 diabetes: NutriNet-Santé. Lancet Diabetes Endocrinol, 2024. PubMed 38663950 · doi:10.1016/S2213-8587(24)00086-X
This guide is for general education. It is not medical advice and does not replace advice from your doctor, pediatrician, allergist or registered dietitian. If you think you or your child reacted to a food, talk to a health professional. Research changes; we review these pages when new evidence or rules come out. Last reviewed October 18, 2026. Spotted an error? Email [email protected].