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

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).