Food-grade carrageenans and their implications in health and disease.

Food additives, often used to guarantee the texture, shelf-life, taste, and appearance of processed foods, have gained widespread attention due to their increased link to the growing incidence of chronic diseases. As one of the most common additives, carrageenans have been used in human diets for hundreds of years. While classified as generally recognized as safe (GRAS) for human consumption, numerous studies since the 1980s have suggested that carrageenans, particularly those with random coil conformations, may have adverse effects on gastrointestinal health, including aggravating intestinal inflammation. While these studies have provided some evidence of adverse effects, the topic is still controversial. Some have suggested that the negative consequence of the consumption of carrageenans may be structure dependent. Furthermore, pre-existing conditions may predispose individuals to varied outcomes of carrageenan intake. In this review, structure-function relationships of various carrageenans in the context of food safety are discussed. We reviewed the molecular mechanisms by which carrageenans exert their biological effects. We summarized the findings associated with carrageenan intake in animal models and clinical trials. Moreover, we examined the interactions between carrageenans and the gut microbiome in the pathogenesis of gastrointestinal disorders. This review argues for personalized guidance on carrageenan intake based on individuals' health status. Future research efforts that aim to close the knowledge gap on the effect of low-dose and chronic carrageenan intake as well as interactions among food additives should be conducive to the improved safety profile of carrageenans in processed food products.

Phospholipid-rich krill oil promotes intestinal health by strengthening beneficial gut microbial interactions in an infectious colitis model.

Krill oil (KO) is rich in bioactive ingredients including phospholipids, omega-3 fatty acids, and astaxanthin. While health benefits and roles of KO in modulating lipid metabolism are well documented, its ability to alleviate symptoms related to infectious colitis and modulate gut microbial interactions is still largely unknown. Here we used a multi-omics approach, including transcriptome, microbiome, and metabolome analyses, to understand how KO mediates gut microbial interactions and promotes epithelial healing in an infectious colitis model. KO reversed the infection-induced intestinal hyperplasia to baseline. KO dampened intestinal inflammation via multiple targets, mediating several proinflammatory pathways, including IL17 signaling, and reducing luminal histamine levels. KO supplementation enriched butyrate-producing bacteria, including Roseburia and Clostridium, and strengthened beneficial microbial interactions in the gut microbial community. Supplementation with phospholipid-rich KO also increased microbial phylogenetic diversity. KO enhanced mucosal barrier function by increasing the production of Muc6 and the antimicrobial peptide, Leap2. KO played an active role during epithelial healing by inhibiting the expression of granzyme K while increasing the expression of a colitis protective factor, Dclk1. Together, our findings demonstrate that KO rich in omega-3 phospholipids can play a protective role in infectious colitis and should be considered a dietary option for promoting gut health.