The human body lacks the enzyme to digest inulin, it passes through the gut and feeds the gut bacteria, which I guess is why it's labeled a pro-biotic? Jerusalem artichoke (the root of a sunflower, Jerusalem is a corruption of girasole) contains a high concentration of inulin. This tuber is usually found served at upper-end swanky restaurants. One year I found it at a farmer's market, bought a bunch and gleefully carted it home. It was rather delicious. Also, gas that would turn a cow inside out. Beware.