Subsequently, the subjects consumed a fat-reduced diet which provided 30% energy as fat and 55% energy as carbohydrate for a period of 64 d using inulin as a fat replacer. Inulin significantly increased bifidobacteria from 9. 8 to 11. 0 log10/g dry faeces and caused a moderate increase in gastrointestinal symptoms such as flatulence and bloatedness, whereas blood lipids and short-chain fatty acids remained essentially unaffected. Prebiotic carbohydrates modify the mucosa associated microflora.