The aim of this study is to demonstrate the beneficial effects on gut microbiota composition and activity of the diary intake of insoluble fiber (extract from Aspergillus Niger) for three weeks. The first studies about the fiber have shown a favorable gut microbiota modulation and an improvement of metabolic parameters like LDL cholesterol. In addition to fecal measurements, several biomarkers of colic fermentation will be assessed: expired gases, PolyUnsaturated Fatty Acid, Short Chain Fatty Acid (SCFA) after a rich-fiber breakfast (= 15 grams) and a nutritional challenge test at lunch. The gastrointestinal tolerance of fiber intake and the intestinal transit modification will be also followed during all the study.
Inclusion Criteria: * Healthy * Non-smokers * Body mass index between 25 and 35 kg/m2 * Waist circumference \< 80cm for women and \> 94 cm for men * Fiber intake \<25g/day Exclusion Criteria: * Medical history of digestive surgery or disease * Current or recent (\<12 weeks) intake of antibiotics or gastro-intestinal medicinal product * Current probiotics, prebiotics, fiber complement, and/or any products modulation gut transit * Feeding particular diet such as vegetarian diet or hyperprotein diet * Current weight loss diet * Pregnant or lactating woman or woman who did not use effective contraception * Drinking more than 3 glasses of alcohol per day (\>30g/day)