What is it?
A thickener made from cellulose, the main structural fiber of plants, that has been chemically modified with carboxymethyl groups and turned into its sodium salt. It thickens, binds and stabilizes lotions, creams, cleansers and other personal care products, and it is widely used in foods as the additive E466, where it is often called carboxymethylcellulose or CMC.
Key information
- The CIR Expert Panel lists cellulose gum as safe in the present practices of use and concentration in cosmetics.
- In 2018 the European Food Safety Authority found no need for a numerical daily limit for celluloses, including E466, and no safety concern at reported uses.
- Celluloses are not absorbed from the gut and pass out of the body intact.
- Research on emulsifiers and gut bacteria concerns eating it, not using it on skin or hair.
More information
Cellulose gum is the cosmetic name for sodium carboxymethyl cellulose. Adding carboxymethyl groups to cellulose makes a polymer that thickens water-based products, binds ingredients together and forms films. The Cosmetic Ingredient Review (CIR) Expert Panel first assessed it in 1986 and again in a 2009 report, and lists it as safe in the present practices of use and concentration.
Food regulators have reached similar conclusions. The Joint FAO/WHO Expert Committee on Food Additives includes it in a group of modified celluloses with an acceptable daily intake of “not specified,” while noting that modified celluloses can have a laxative effect in some people at intakes as low as 5 grams a day. In 2018 the European Food Safety Authority found that celluloses are not absorbed, pass through the body intact, showed no genotoxic or cancer-causing effects in studies, and raise no safety concern at reported uses. It said the data were not enough to assess its use in special formulas for infants and young children.
You may read that cellulose gum harms gut bacteria. That concern comes from research on food emulsifiers, including mouse studies. In a small 2022 controlled-feeding study, 7 healthy adults who ate 15 grams of carboxymethylcellulose a day for 11 days had modestly more abdominal discomfort and less diverse gut bacteria than 9 people on the same diet without it, and the authors suggested that its broad use in processed food could contribute to inflammatory disease.
Reality check: in skin and hair products, cellulose gum is considered low risk. The open questions are about eating it in processed foods, and a single small, short study cannot settle them.
Sources: Cosmetic Ingredient Review: Quick reference table, safe findings (2020); WHO/JECFA: Modified celluloses (WHO Food Additives Series 26); European Commission: Summary of EFSA’s 2018 re-evaluation of celluloses, including E 466 (2023); Gastroenterology (2022): Randomized controlled-feeding study of dietary emulsifier carboxymethylcellulose
