Inulin

Inulin is a naturally occurring storage polysaccharide found in many plants. It belongs to the fructan family and consists of linear chains of fructose units linked by β-(2→1) glycosidic bonds, typically terminating with a glucose residue. The degree of polymerization ranges from about 2 to several dozen units.

Natural sources include chicory root, Jerusalem artichoke, onions, garlic, leeks, dandelion, and agave. In humans, inulin is not digested by the enzymes of the small intestine and passes into the colon, where gut bacteria ferment it to short-chain fatty acids such as acetate, propionate, and butyrate. As an fermentable fiber and prebiotic, inulin promotes the growth of beneficial bacteria, particularly bifidobacteria.

Health effects attributed to inulin include improvements in mineral absorption under certain conditions, such as calcium and magnesium uptake, though evidence is mixed. It can also influence bowel habits by increasing fecal bulk. At higher intakes, inulin can cause gas, bloating, and abdominal discomfort, and may exacerbate symptoms in people with irritable bowel syndrome or other fermentable carbohydrate sensitivities.

Uses in food processing include increasing dietary fiber content, modifying texture, and providing mild sweetness. It is used as a fat replacer and is a common prebiotic ingredient in many processed foods.

In laboratory settings, inulin is used as a marker to measure glomerular filtration rate (inulin clearance) due to its elimination characteristics. Overall, inulin is valued as a dietary fiber and prebiotic with multiple functional applications, but tolerability varies among individuals.