Fibre is a type of (non-digestible) carbohydrate that plays a key role in normal digestion. There are 2 types: soluble and insoluble.
Unlike other complex carbs, fibre cannot be broken down by the human digestive system, so most of it passes undigested through the small intestine; providing bulk.
As the most important dietary factor for helping to maintain normal gastrointestinal function, adults should aim to consume 25 g fibre per day. Yet research shows that in some European countries the average fibre intake is less than half of the recommended amount. If your current fibre intake is low, increase fibre consumption gradually and drink plenty of water.