Dietary fibre: mechanisms of action

Actions of dietary fibre in the gut may be important in the control of energy intake and energy digestibility. These include effects on gastric emptying, upper small gut motility, rates and completeness of carbohydrate, fat and protein absorption in the gut. The ileal brake, whereby fat in the terminal ileum slows upper gut motility and inhibits ad-lib food intake, demands further investigation. Energy digestibility may be important, but large changes of fibre intake result in only small changes in digestibility. Gastrointestinal hormone release which may be affected by fibre is another topic for further investigation, and the effect of some types of fibre in reducing postprandial blood glucose and insulin levels, and thereby increasing insulin sensitivity, may be important for lipolysis and lipogenesis.