Sea tangle (Saccharina japonica), an edible brown seaweed, improves serum lipid profiles and antioxidant status in rats fed high-fat and high-cholesterol diets

Abstract

In the present study, daily consumption of sea tangle (Saccharina japonica) was assessed for beneficial effects on blood lipid profiles and antioxidant status in rats fed high-fat and high-cholesterol diets (20% fat and 1% cholesterol, wt/wt) for 7 weeks. Thirty-six male Sprague-Dawley rats (average weight 170 g), 5-week old, were randomly divided into six groups: (1) a normal diet group (NOR), (2) a high-fat/high-cholesterol diet group (CON), and the high-fat/high-cholesterol diet combined with (3) 1% silk-shaped sea tangle powder (SST1), (4) 2% silk-shaped sea tangle powder (SST2), (5) 1% commercial sea tangle powder (CST1), and (6) 2% commercial sea tangle powder (wt/wt) (CST2) groups after a 2-week acclimation. The body weight gain and weight of adipose tissues in the CON group was increased compared with that of the NOR group, whereas those of the groups fed sea tangle decreased gradually. Serum triglyceride, total cholesterol, LDL-cholesterol levels, atherogenic index, and cardiac risk factors significantly and dose-dependently decreased in the sea tangle-fed groups when compared with the CON group, whereas serum HDL-cholesterol levels tended to increase in the sea tangle-fed groups. Moreover, serum and hepatic glutathione (GSH) levels and antioxidant enzyme activities such as superoxide dismutase (SOD) and catalase (CAT) were significantly improved in the sea tangle-fed groups compared with the CON group. In particular, serum LDL-cholesterol levels, GSH, SOD, and CAT activities were significantly and dose-dependently improved in the SST groups compared with the CST groups. Interestingly, sea tangle supplementation markedly reduced the hepatic lipid regulating enzyme activities including those of fatty acid synthase, HMG-CoA reductase, and acyl-coenzyme A: cholesterol acyltransferase. These results suggest that sea tangle, especially SST supplementation, may be potentially beneficial for preventing dyslipidemia-associated chronic diseases by improving blood lipid profiles and antioxidant properties due to its greater soluble alginate content and lower molecular weight.