Inulin is a starchy substance found in a wide variety of fruits, vegetables, and herbs, including wheat, onions, bananas, leeks, artichokes, and asparagus.The inulin that is used for medicine is most commonly obtained by soaking chicory roots in hot water.Inulin is used for high blood fats, including cholesterol and triglycerides. It is also used for weight loss, constipation, and as a food additive to improve taste.he inulin that is used for medicine is most commonly obtained by soaking chicory roots in hot water. Inulin is used for high blood fats, including cholesterol and triglycerides. It is also used for weight loss, constipation, and as a food additive to improve taste.