Tapioca fiber is a prebiotic (i.e., gut-friendly) fiber known as a “resistant dextrin”. It is isolated by heating the tapioca root (also known as the cassava root) and extracting its fiber content. While the FDA has recently re-classified certain compounds formerly labeled “fiber” as non-fiber carbohydrates, it has remained firm in its classification of resistant dextrin as a 100% legitimate fiber. Tapioca fiber is NOT to be confused with isomalto-oligosaccharide (usually referred to as IMO), which can also be derived from the tapioca root. IMO is not a resistant dextrin, but rather a fiber-like sweetener that the body almost completely breaks down into blood glucose. Here is a great study on the topic, where scientists compare Soluble Corn Fiber (which is virtually chemically identical to Tapioca Fiber) to IMO and find a vast difference in blood sugar and insulin response.