CLDN1 and colitis: Additionally, the Claudin-1 and Occludin protein expression levels were also found to significantly decrease in mice from the DSS group, while algal oil treatment, especially 500 mg/kg/day of algal oil, obviously reversed the changes of Claudin-1 (p < 0.05) and Occludin (p < 0.05) expression in colitis mice (Figure 4B).