Revisiting the carrageenan controversy: do we really understand the digestive fate and safety of carrageenan in our foods?

Abstract

Carrageenan (CGN), a family of marine polysaccharides isolated from seaweeds, has been at the heart of considerable debate in recent years. To date, CGN is generally recognized as safe based on a history of safe use, various acute toxicology studies and some recent chronic toxicology tests. This review offers readers an overview of evidence on CGN characteristics and digestive fate that highlight various gaps in our understanding. Specifically, three unresolved gaps are identified. Firstly, little information can be found on the current levels of public exposure to CGN. Secondly, the link between CGN physicochemical properties, its impact on digestive proteolysis, the colon microbiome and inflammation are yet to be fully resolved. Thirdly, scant scientific evidence exists on the differential digestive fate of CGN in the gut of liable and predisposed populations, such as elderly people or IBD patients. Altogether, revisiting the scientific evidence indicates that more research is needed to elucidate the possibility that continued exposure to increasing levels of CGN in the human diet may compromise human health and well-being.

Carrageenan oligosaccharides and their degrading bacteria induce intestinal inflammation in germ-free mouse

“…κ-CGNs are sulfurized seaweed polysaccharides with thermo-reversible gelling properties that are widely used as food thickening agent. However, the safety of κ-CGNs remains a concern [1].…”

“…β-1-3 and α-1-4 linkage of galactose residues and additional substitute residues, including xylose, glucose, methyl esters, and pyruvate groups [1]. CGNs can be divided into kappa (κ-), iota (ι-), lambda (λ), and other types, based on the different forms of sulfate bonds in CGN molecules [2].…”

“…CGNs can be divided into kappa (κ-), iota (ι-), lambda (λ), and other types, based on the different forms of sulfate bonds in CGN molecules [2]. κ-CGN is mainly composed of D-galactose-4-sulfate and 3,6-D-anhydrogalactose, with 22% sulphate content in commercial κ-CGN [1]. Because of its linear structure, κ-CGN demonstrates good gel properties and is widely used in food and pharmaceutical industries [3,4].…”

“…Despite the fact that CGNs have been widely used in food industries for decades, their safety is still a topic of discussion [1,12,13]. A large number of animal experiments have shown that CGNs, particularly low-molecular-weight (low-MW) CGNs, can induce and promote the inflammatory response and intestinal cancer [14][15][16][17][18][19][20][21][22][23][24][25][26].…”

“…A large number of animal experiments have shown that CGNs, particularly low-molecular-weight (low-MW) CGNs, can induce and promote the inflammatory response and intestinal cancer [14][15][16][17][18][19][20][21][22][23][24][25][26]. Indeed, poligeenan, which is designated as a fraction of CGN with Mw < 100 kDa, has been considered to exert deleterious impacts on the host health and recognized as food contaminant [1]. On the other hand, CGN polysaccharides are widely used as food additive and classified by the Food and Drug administration (FDA) and European Food Safety Authority as generally recognized as safe (GRAS) even in the infant formula.…”