Reduction Effect of Calcium Alginate on Blood Triglyceride Levels Causing the Inhibition of Hepatic and Total Body Accumulation of Fat in Rats

• Published in: Biological & pharmaceutical bulletin 2019/03/01, Vol.42(3), pp.365-372
• Main Authors: Kasahara, Fumiyoshi, Kato, Takako, Idota, Yoko, Takahashi, Hitoe, Kakinuma, Chihaya, Yano, Kentaro, Arakawa, Hiroshi, Hara, Kurt, Miyajima, Chihiro, Ogihara, Takuo
• Format: Article
• Language: English
• Subjects: Absorption; Accumulation; Alginic acid; Blood levels; Body fat; Body weight; Calcium; Calcium (blood); Calcium alginate; Clinical trials; Excretion; fat; High fat diet; Lipase; lipid; Lipid metabolism; Liver; Macromolecules; Maltodextrin; micelle; Micelles; Rodents; triglyceride; Vacuoles
• ISSN: 0918-6158; 1347-5215
• DOI: 10.1248/bpb.b18-00530

In this study, rats were fed a high-fat diet containing calcium alginate (Ca-Alg) for 5 weeks to examine the effects of Ca-Alg on lipid metabolism including triglyceride (TG) levels in the blood. We also investigated the mechanism of the TG-reducing effect of Alg in vitro. Rats were randomized into 5 groups: high-fat diet group (14% (w/w) lard, HF); three Ca-Alg-containing diet groups (2.5, 5 or 10% (w/w) Ca-Alg) and a resistant maltodextrin (RMD) diet group as a positive control (with 5% (w/w) RMD). The 10% Ca-Alg group showed a significant reduction of body weight increase from the 7th day. In addition, the increase of TG in blood was significantly suppressed, and the amount of TG excreted in feces was increased. Increase of body fat mass was in the order HF > RMD > Ca-Alg 2.5% > Ca-Alg 5% > Ca-Alg 10%, while the total weight of the extracted fat tissues was significantly reduced in the RMD, 5% and 10% Ca-Alg groups. Hepatic pathology showed clear circular vacuoles apparently representing TG accumulation in the HF group, while fewer vacuoles were seen in the Ca-Alg groups. The results of in vitro experiments indicated that Ca-Alg does not directly inhibit lipase activity, but may suppress absorption of TG by forming non-absorbable macromolecular micelles containing TG. These results suggest that Ca-Alg promotes excretion and suppresses absorption of TG, leading to reduced blood TG levels, and decreased hepatic and total body accumulation of fat. The findings should be helpful for designing future clinical trials.