What Is Carrageenan? Is It Bad for You?

Carrageenan Facts
Carrageenan is a polysaccharide from edible red seaweed that is an additive in many common products.

Carrageenan is the name given to a group of sulfated polysaccharides extracted from edible red seaweed. Irish moss (Chondrus crispus) is the most common source of the molecule, although it occurs in other species of seaweed. Although carrageenan is a common food additive and serves roles in other products, its use is controversial because of potential negative health effects. Here is a look at the uses of carrageenan, products that contain it, and an overview of the safety controversy.

  • Carrageenan is a natural polymer purified from red seaweed.
  • It finds use as a gelling agent, stabilizer, and thickener.
  • Studies find carrageenan safe for use in most applications, but it may pose health risks in some situations.

Carrageenan Uses

Carrageenan forms gels at room temperature, which makes it handy for gelling liquids, thickening them, and stabilizing mixtures. Because it comes from seaweed, it is a vegetarian and vegan alternative to gelatin. In medicine, it helps deliver time-release doses, dresses wounds, and aids in tissue engineering. Carrageenan is non-toxic, biodegradable, and biocompatible.

Products That Contain Carrageenan

An incredible array of products contain carrageenan, including:

  • Ice cream
  • Creamer
  • Milkshakes
  • Chocolate milk
  • Plant-based milk
  • Sauces
  • Beer (as a clarifier to remove haze)
  • Processed meats (often as a fat substitute or to improve water retention or slicing)
  • Vegetarian meat
  • Toothpaste (as a stabilizer)
  • Shampoo and conditioner
  • Cosmetic creams
  • Air freshener gels
  • Fruit gushers and related candies
  • Fire-fighting foam (so the foam sticks to surfaces)
  • Shoe polish
  • Pills, tables, and gel caplets
  • Paper and fabric marbling agents
  • Diet soda (for texture)
  • Pet food
  • Personal lubricant
  • Baby formula

How Is Carrageenan Made?

People have been purifying carrageenan for a long time, dating to around 600 BCE in China and 400 CE in Ireland. The process involves boiling about 140 grams (5 ounces) of rinsed Irish moss in 9 liters (8 quarts) of water for about 10 minutes. Next, rapidly add 2.5 liters (2 quarts) of cold water. Straining the resulting mixture through a cloth and cooling to room temperature yields carrageenan.

The industrial process is a bit more involved and results in a higher-purity product. The first step is treating the dried seaweed with hot alkali (5-8% potassium hydroxide) and removing the cellulose with centrifugation and filtration. This leaves a solution containing carrageenan, which is concentrated by evaporation. Some processes concentrate the product using potassium chloride or alcohol. Different species of seaweed yield different types of carrageenan.

Types of Carrageenan

Carrageenan is not a single compound, but rather a family of related anionic, helical organic molecules that contain 15-40% ester-sulfates. They are classified according to their sulfate content. The three most commonly-used types of carrageenan are kappa, iota, and lambda:

  • Kappa-carrageenan has one sulfate group per disaccharide subunit (galactose). It mainly comes from Kappaphycus alvarezii. This type of carrageenan forms rigid gels, but reacts with protein from dairy.
  • Iota-carrageenan has two sulfate groups per disaccharide. Its source is Eucheuma denticulatum. This form of carrageenan forms soft gels in the presence of calcium.
  • Lambda-carrageenan has three sulfate groups per disaccharide. It does not form a gel, but is a good thickener and does not react with dairy.

Is Carrageenan Safe? The Controversy

The USDA, WHO, and European Food Safety Authority have found carrageenan to be a safe food additive, within certain consumption levels (e.g., 75 milligrams per kilogram of body weight per day). The UK Food Standards Agency recalled its use in jelly sweets as a choking hazard for children. It’s a product people have used for centuries and it has passed a lot of safety tests, so you may be wondering why it’s controversial.

There are a couple of concerns. The first is that one of the degradation products of carrageenan is a polymer called poligeenan. Poligeenan has uses in clinical diagnostic tests, but it is not an approved food additive. Studies indicate it may cause gastrointestinal lesions. It is a suspected carcinogen. Exposing carrageenan to acid degrades it into poligeenan. The concern is that stomach acid may convert non-toxic carrageenan into toxic poligeenan. To date, this issue has not been fully resolved.

The other potential problem with carrageenan is that its effect on the gastrointestinal microbiome is poorly understood. Certain populations may be pre-disposed to inflammation and other health effects from carrageenan consumption, including some infants drinking it in formula, elderly persons, or people suffering from IBD or arthritis.

The bottom line is that carrageenan is generally safe in topical products and in foods for most people. However, if it degrades into poligeenan, it may increase the risk of developing cancer. Also, some people are sensitive to carrageenan in the diet and may benefit from avoiding it.


  • David, Shlomit; Shani Levi, Carmit; Fahoum, Lulu; Ungar, Yael; Meyron-Holtz, Esther G.; Shpigelman, Avi; Lesmes, Uri (2018). “Revisiting the carrageenan controversy: Do we really understand the digestive fate and safety of carrageenan in our foods?”. Food & Function. 9 (3): 1344–1352. doi:10.1039/c7fo01721a
  • EFSA Panel on Food Additives and Nutrient Sources added to Food (2018). “Re‐evaluation of carrageenan (E 407) and processed Eucheuma seaweed (E 407a) as food additives”. EFSA Journal. 16 (4): e05238. doi:10.2903/j.efsa.2018.5238
  • Loureiro, Rafael R.; Cornish, M.L.; Neish, Iain C. (2017). “Applications of carrageenan: With special reference to iota and kappa forms as derived from the Eucheumatoid seaweeds”. In Hurtado, Anicia Q.; Critchley, Alan T.; Neish, Iain C. (eds.). Tropical Seaweed Farming Trends, Problems and Opportunities. Berlin, Germany: Springer International Publishing. ISBN 9783319634982.
  • Yegappan, Ramanathan; Selvaprithiviraj, Vignesh; Amirthalingam, Sivashanmugam; Jayakumar, R. (October 2018). “Carrageenan based hydrogels for drug delivery, tissue engineering and wound healing”. Carbohydrate Polymers. 198: 385–400. doi:10.1016/j.carbpol.2018.06.086
  • Zia, Khalid Mahmood; Tabasum, Shazia; Nasif, Muhammad; Sultan, Neelam; Aslam, Nosheen; Noreen, Aqdas; Zuber, Mohammad (March 2017). “A review on synthesis, properties and applications of natural polymer based carrageenan blends and composites”. International Journal of Biological Macromolecules. 96: 282–301. doi:10.1016/j.ijbiomac.2016.11.095