Effect of Optimizing Fiber Intake of Mice on Weight Gain, Fat Mass, Oral Glucose and Insulin Tolerance Tests in Mice Fed a High Fat Diet

Abstract Objectives In humans, fiber intakes close to recommended levels (14g/1000 kcal, Institute of Medicine (IOM)) are associated with less chronic disease. In most semi-purified rodent diets, the only fiber source is cellulose. The main objective of this work was to determine if substituting a complex fiber blend for cellulose would affect metabolism of mice fed a 45% kcal from fat diet. Methods To model a recommended human fiber profile for rodents, the relative proportions of cellulose, hemicellulose, lignin, pectin and beta-glucan were estimated from a one-day meal plan with the recommended fiber level using a food fiber composition database. Subsequently, a mix of oat hull fiber, pectin and beta-glucan was added to a high-fat rodent diet at the typical US intake or at the recommended level (8 g/1000kcal (low), 14 g/1000 kcal (high)). Three groups of C57Bl/6 mice (n = 12) were fed the experimental diets for 16 weeks. The third diet was also high fat but only contained cellulose. Body composition was measured by MRI at weeks 7 and 14. Oral glucose tolerance tests (OGTT) and insulin tolerance tests (ITT), were conducted at weeks 8 and 15 (OGTT) and week 16 (ITT). Results There were no differences in final weight or weight gain in mice between the groups. There was a trend for mice fed the low complex fiber profile diet to have a higher body fat percentage than mice fed the other groups (p = 0.08). However, there were no differences in fasting glucose at week 8 or 15, and no significant differences in OGTT or ITT between the groups. Conclusions Rodent models are used extensively to investigate the role of nutrients in maintaining metabolic health and the prevention of chronic disease. These results indicate that exogenous fiber added to a high fat, semi-purified rodent diet does not improve body composition or glucose metabolism in mice. Funding Sources The National Institute of Food and Agriculture (NIFA).