Zeolite Improves High-Fat Diet-Induced Hyperglycemia, Hyperlipidemia and Obesity in Mice.

Zeolite, an abundant mineral in the Earth's crust, is utilized in a wide range of fields because of its well-known adsorption properties. Its application as a functional food ingredient resembling dietary fiber is expected, but it has not yet been investigated in the context of prevention of lifestyle-related diseases. The present study was designed to evaluate the availability and safety of a natural zeolite preparation for this purpose. Acute oral toxicity testing showed that the lowest lethal dose of zeolite was more than 2,000 mg/kg body weight for both male and female mice. In a prolonged feeding test for 18 wk using model mice with high-fat-induced obesity and type 2 diabetes mellitus, intake of a 10% zeolite-containing diet suppressed body weight gain, as well as liver and visceral fat weights, without any changes in food and energy intake. Moreover, plasma lipid (triacylglycerol, total cholesterol and high-density-lipoprotein cholesterol) levels and fasting blood glucose levels decreased in parallel with zeolite intake. No changes in the glycated hemoglobin level were found. However, in an oral glucose tolerance test at week 12, increased postprandial blood glucose levels were suppressed in accordance with zeolite intake, and then insulin secretion was also decreased. On the other hand, a decrease of plasma amylase activity and increases in total bilirubin and urea nitrogen suggested the need for further investigation of safety.