What Is Inulin Fiber?

Inulin is both a fiber and a sugar. It is used as a fat substitute and a fuel source. Inulin fiber is used to help measure kidney function, can be converted into ethanol, and there is even evidence that it can assist in the management of diabetes (though it is not to be confused with insulin). But what exactly is inulin fiber and where does it come from? Here are a few facts about this little discussed, but frequently consumed nutrient.

A Dietary Fiber

In nutritional terminology, inulin is most broadly categorized as a dietary (or edible) fiber because it passes through the digestive tract largely undigested. Ironically, inulin, like many of the so-called dietary fibers, does not contain any actual fibers.

A Soluble Fiber

Dietary fiber falls into two broad categories: soluble and insoluble. Neither are absorbed by the digestive tract, but soluble fiber dissolves in water, whereas insoluble fiber does not. Another feature of soluble fibers is that, although they are not broken down by the human digestive tract, they are partially digested by bacteria which inhabit the colon. Inulin is a soluble fiber.

A Fiber Composed of Sugars

Chemically, inulin belongs to a family of fibers known as fructans, which are polymers of fructose (groups of simple sugars linked together). Fructans are used by plants to store energy. An interesting feature of fructans is that they enable plants to thrive in low temperatures, by helping the cell membranes to remain intact even when frozen.

So Where Does it Come From?

Inulin is found in abundance in many non-starchy root vegetables and rhizomes such as burdock roots, Jerusalem artichokes, onions, and garlic. Most of the inulin fiber that is used as a food additive comes from chicory roots (which look similar to small beet roots) because of their consistently high inulin content.

Dietary Uses of Inulin Fiber

Inulin fiber has come to be increasingly used as a food additive because it is sweet-tasting, yet very low in calories, creamy in texture, yet completely fat-free, and can even help with the absorption of certain minerals.

Non-Dietary Uses of Inulin Fiber

Inulin is also used to help indicate kidney health by determining the rate at which the kidneys are filtering fluids. It may also have potential as a fuel source, as there are fermentation processes which can convert certain types of inulin directly into ethanol.