Concomitant short-term ingestion of fucoidan improves the initial inflammation and immune dysfunction caused by a high-fat diet.

We examined the effects of fucoidan, a sulfated polysaccharide, administered concurrently with the onset of a high-fat diet (HFD) for a short period in C57BL/6 N mice to evaluate its immunological effects under obesity-inducing conditions. Numerous genes that were downregulated in the HFD group relative to the control-diet group were restored in the HFD + fucoidan group; these genes were mainly associated with inflammatory responses and cellular functions, including migration and viability, as identified by DNA microarray analysis. Upstream regulator analysis in ingenuity pathway analysis identified numerous cytokines and inflammatory mediators. Quantitative PCR confirmed that the expression of selected inflammatory cytokine genes-particularly Ifn-γ and Il-5-was decreased in the HFD group but restored in the HFD + fucoidan group. Our study suggests that fucoidan administered concurrently with an HFD attenuates HFD-induced downregulation of inflammatory and immune-related functions, including T- and B-cell functions, and may improve HFD-induced immune dysfunction and imbalance.