Last reviewed: 11 May 2026
Red seaweed extract — thickener for dairy, plant milks and ice cream. An unresolved gut-inflammation signal.
E407 is food-grade carrageenan, a high-molecular-weight polysaccharide extracted from red seaweed (Chondrus crispus, Eucheuma and related species). It is essential to distinguish food-grade carrageenan from degraded carrageenan (poligeenan) — a low-molecular-weight, chemically distinct substance that is not authorised in food and that IARC has classified as Group 2B, possibly carcinogenic to humans. Animal and in-vitro research suggests that even food-grade carrageenan can produce intestinal inflammation, particularly in compromised gut tissue, by activating pro-inflammatory pathways. The clinical relevance of these findings in humans on normal dietary intakes is contested in the published literature. EFSA's 2018 re-evaluation maintained the existing approval, did not set a new numerical ADI for the general population, and lowered the permitted use in infant formula pending further research.
Carrageenan is a family of sulphated polysaccharides extracted from red seaweed. Three main fractions are used industrially — kappa, iota and lambda — distinguished by sulphate-group positions and by the gel they form (kappa forms firm brittle gels with potassium, iota soft elastic gels with calcium, lambda thickens without gelling). The food-grade specification (E407) requires high molecular weight, generally above 100,000 daltons, and tight limits on the low-molecular-weight fraction. The chemistry: red seaweed is harvested (mainly from the Philippines, Indonesia and Chile), the carrageenan is extracted under hot alkaline conditions, filtered, and either alcohol-precipitated (refined carrageenan) or recovered by drying (semi-refined carrageenan, classed as E407a — processed Eucheuma seaweed).
The distinction with poligeenan matters because the two are routinely conflated in online sources. Poligeenan is produced by deliberate acid hydrolysis of carrageenan at high temperature, yielding a low-molecular-weight (10,000–20,000 daltons) substance with very different biological behaviour. Poligeenan is used in laboratory animal models as a chemical inducer of colitis — it reliably produces intestinal inflammation in rodents — and is classified by IARC as Group 2B possibly carcinogenic. Poligeenan is not permitted as a food additive and is not present in compliant E407 carrageenan. The substantive scientific question is whether food-grade carrageenan partially breaks down into poligeenan-like fragments in the human gut (under acidic conditions, in inflamed tissue, or via gut microbial action), and whether the parent high-molecular-weight carrageenan can itself trigger inflammatory pathways without that breakdown step.
On a UK label the additive appears as E407, carrageenan, seaweed extract, or — for the semi-refined product — E407a or processed Eucheuma seaweed.
EFSA published its re-evaluation of carrageenan as a food additive in 2018 (EFSA Journal 2018;16(4):5238). The opinion's key findings:
Decades of in-vivo and in-vitro work — from Watt and Marcus's guinea-pig colitis models in the 1960s through to current cell-culture studies — show that carrageenan exposure activates NF-κB and other pro-inflammatory signalling in intestinal cells, and can trigger or worsen colitis in animal models. The contested question is whether these findings translate to people eating typical dietary amounts. Researchers who argue food-grade carrageenan is implicated point to in-vitro work on human intestinal cell lines and small clinical observations in inflammatory bowel disease cohorts. Researchers who argue against direct human relevance point to the high doses used in animal models, the gut-tissue-state requirement (most positive findings need pre-existing inflammation or breached epithelium), and the absence of large, well-controlled human trials showing harm at dietary intakes. The clinical relevance is not settled.
Some IBD clinicians and patient organisations include carrageenan on lists of foods worth trial-eliminating during active disease, on the basis that the in-vitro and animal evidence suggests it may worsen inflamed mucosa and the dietary opportunity cost of avoiding it is low (alternative thickeners like guar gum E412 and xanthan gum E415 are widely substituted). The NHS does not single carrageenan out in its general IBD dietary guidance. If you have IBD and are considering elimination, the practical step is to log your symptoms alongside carrageenan-containing products and discuss with a registered dietitian — we are a tracking tool, not a clinical one.
If you want to avoid carrageenan, look in the ingredients list for E407, E407a, carrageenan, seaweed extract or processed Eucheuma seaweed. Plant-milk packaging has been the most responsive category — many UK plant-milk brands now make "carrageenan-free" a front-of-pack claim. Alternative thickeners you'll see filling the same functional slot include guar gum (E412), xanthan gum (E415), locust bean gum (E410), gellan gum (E418) and pectin (E440); none carry the same animal-model inflammation signal as carrageenan.
UK and EU: authorised as E407 (carrageenan) and E407a (processed Eucheuma seaweed). No numerical ADI specified; EFSA 2018 opinion in force. Permitted uses listed in Annex II of Regulation (EC) No 1333/2008. Restricted in infant formula following the 2018 re-evaluation.
United States: FDA Generally Recognized as Safe (GRAS) for use as a food ingredient.
IARC: degraded carrageenan (poligeenan) — a distinct substance, not used in food — classified Group 2B possibly carcinogenic to humans (IARC Monograph). Food-grade carrageenan is not classified by IARC.
Scan any UK pack in NutraSafe and we surface carrageenan — by E-number and named ingredient — alongside the rest of the additives, so it's easy to compare brands or find carrageenan-free alternatives.
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