<i>Saccharina japonica</i> sulfated fucans alleviate intestinal ageing‐associated epithelial deterioration and regenerative decline

BACKGROUND: Intestinal ageing is characterized by progressive epithelial deterioration, barrier dysfunction and impaired regenerative capacity, which together contribute to age-related intestinal decline. Sulfated fucans derived from Saccharina japonica (SJ-FUC) are marine polysaccharides with potential bioactivities, although their role in intestinal ageing remains unclear. This study investigated the protective effects of SJ-FUC in a D-galactose-induced ageing mouse model. RESULTS: Administration of SJ-FUC significantly alleviated intestinal ageing-associated phenotypes by reducing oxidative stress, suppressing senescence-associated secretory phenotype-related inflammatory cytokines, and downregulating the senescence markers P53, P16 and P21. Histological analysis showed marked improvement in ileal architecture and epithelial barrier integrity. SJ-FUC also mitigated ageing-associated regenerative decline, as indicated by increased expression of intestinal stem cell-related markers Lgr5, Ascl2 and Olfm4, elevated numbers of Olfm4-positive and Ki67-positive cells in ileal crypts, and restoration of Wnt/β-catenin signalling. In addition, SJ-FUC promoted goblet and Paneth cell differentiation. 16S rRNA sequencing further showed that SJ-FUC remodelled gut microbial composition, characterized by enrichment of beneficial taxa such as Lactobacillus and reduction of potentially detrimental bacteria including Bacteroides. CONCLUSION: Sulfated fucans from Saccharina japonica alleviate intestinal ageing by preserving epithelial integrity and restoring regenerative capacity, supporting their potential as functional marine polysaccharides for improving age-related intestinal dysfunction. © 2026 Society of Chemical Industry.