FOS is extracted from the blue Agave plant as well as fruits and vegetables such as bananas, onions, chicory root, garlic, asparagus, jícama, and leeks. Some grains and cereals, such as wheat and barley, also contain FOS.[4] The Jerusalem artichoke and its relative yacón together with the Blue Agave plant have been found to have the highest concentrations of FOS of cultured plants.[5]