Inulin is a type of dietary fiber that is found in many plants, including chicory, wheat, onion, bananas, garlic, asparagus, Jerusalem artichoke, and agave. It is a natural storage carbohydrate present in more than 36,000 species of plants, and is used as an energy reserve and for regulating cold resistance. Inulin is a heterogeneous collection of fructose polymers, consisting of chain-terminating glucosyl moieties and a repetitive fructosyl moiety, which are linked by β(2,1) bonds. It is a soluble fiber, one of three types of dietary fiber including soluble, insoluble, and resistant starch. When inulin mixes with water or other fluids in the body, it turns into a gel, which makes the stomach empty much slower, leading to a feeling of fullness and helping to stabilize blood sugar levels. Inulin is also a prebiotic fiber, meaning that it feeds the good bacteria in the gut, and can help increase the amount of calcium and other minerals absorbed from food, support a healthy immune system, and relieve intestinal problems. Inulin is used by some plants as an osmotically active energy reserve, and certain plants can change the osmotic potential of their cells by changing the degree of polymerization of inulin molecules by hydrolysis. Inulin is available in supplement form or as an ingredient in various foods, including protein bars, cereal bars, yogurts, drinks, baked goods, and desserts. The most common side effects of inulin include gas, bloating, diarrhea, constipation, and cramps, which are more severe with high doses of inulin.