fructans

Fructans are a class of polysaccharides made up mainly of fructose units. In many plant fructans, a terminal glucose is attached to a chain of fructose, forming polymers such as inulins (linked by β-2,1 bonds) and levans (linked by β-2,6 bonds). They vary in length from short-chain fructooligosaccharides to long-chain inulin, with degrees of polymerization ranging from a few to several dozen units.

Fructans occur naturally in a wide range of plants as storage carbohydrates. Common sources include chicory root, Jerusalem artichoke, onions, garlic, wheat, and bananas. They are often found in the edible roots and stems rather than in the leaves, and their abundance can vary with plant species and growing conditions.

Digestive and metabolic aspects: humans do not produce enzymes to fully digest fructans in the small intestine, so they reach the colon intact. There, gut bacteria ferment them, producing short-chain fatty acids and gas. As fermentable dietary fibers and prebiotics, fructans can support beneficial microbes such as Bifidobacteria and may aid mineral absorption and gut health. However, because they are fermentable, they can cause bloating or discomfort in some individuals, particularly those with irritable bowel syndrome. They are also categorized as FODMAPs, which can influence tolerability for some people.

Uses and production: fructans are employed as dietary fibers and functional ingredients in foods, offering texture improvement and mild sweetness in the case of FOS. They can be extracted from chicory or produced enzymatically. They are generally regarded as safe when consumed in typical amounts.