Fructans are a type of FODMAP. FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols. Fructans are found in bananas (more in ripe bananas) as well as in onions, rye, garlic, lentils, some cabbage, asparagus, to name a few foods. Fructans can trigger IBS symptoms.