6. Fructan Prebiotics Derived from Inulin

Inulin, as well as the shorter form oligofructose, is a nondigestible carbohydrate (fructan) that has been part of the daily food of mankind for centuries. Inulin-type fructans naturally occur in many edible plants as storage carbohydrates. They are present in leek, onion, garlic, wheat, chicory, artichoke, and banana. It is estimated that an average North American consumes about 1–4 g/day of inulin or oligofructose. In Western Europe, the average intake varies between 3 and 10 g/day. Occasionally, people can have higher intakes, e.g., after consuming a bowl of French onion soup, salsify dish, etc., and intakes can then exceed easily 10 g. This illustrates that via the normal diet some, and at certain times, all populations consume relatively high quantities of inulin-type fructans. It also follows that wheat, onion, and banana, and to a lesser extend garlic are the most important sources of inulin-type fructans in the diet. Although inulin-type fructans are nutritive substances and part of our daily diet, these compounds are currently not taken up in food composition tables.