Anti-Obesity Properties of the Dietary Green Alga, Codium cylindricum, in High-Fat Diet-Induced Obese Mice

Marine carotenoids have been reported to prevent and alleviate lifestyle-related diseases including diabetes and obesity. We previously reported that siphonaxanthin, a green algal carotenoid, effectively suppresses adipogenesis in 3T3-L1 cells and prevents lipid accumulation in mesenteric adipose tissue of KK-Ay mice. Thus, we expect that dietary siphonaxanthin-rich marine green algae may effectively prevent obesity. Here, we assessed the effect of dietary siphonaxanthin-rich green algae (Codium cylindricum) on the development of diet-induced obesity in C57BL/6J mice. The mice were fed a low-fat diet (LF; 7% fat, w/w), a high-fat diet (HF; 35% fat, w/w), or a high-fat diet supplemented with 1% or 5% green algal powder (1GA or 5GA) for 78 d. Our results showed that weights of body and perirenal white adipose tissue (WAT) in the 5GA group were significantly lower than that in the HF group. The mesenteric and total WAT, as well as plasma and hepatic cholesterol concentrations tended to be lower in both the 1GA and 5GA groups compared to the HF group. Dietary green algal powder reduced the expression of lipogenesis-related genes and enhanced the expression of energy expenditure-related genes in the mesenteric WAT. Siphonaxanthin accumulated in the mesenteric WAT may contribute to the prevention of adiposity in mesenteric WAT. Furthermore, the reduction in the weight of WAT was attributed to the inhibitory effect on fat absorption of dietary fiber contained in the green algae. Overall, these results indicated that siphonaxanthin-rich green algae may be beneficial for the prevention of obesity and regulation of lipid metabolism.