Inulin is a form of the sugar fructose in which the fructose molecules are bound together in long chains called polymers. Inulin is found in Jerusalem artichoke, chicory and members of the Allium family such as onions, garlic, leeks and chives. Inulin is also available as a food supplement. (Note that inulin is almost the same word as insulin.)
Many beneficial intestinal bacteria such as Lactobacillus and Bifidobacterium grow well when inulin is provided in the human diet. Inulin is called a prebiotic- because it helps probiotic bacteria like Lactobacillus and Bifidobacterium bacterium grow faster.
Many human and animal studies have reported that provided inulin in the diet can increase growth of beneficial probiotic bacteria like Lactobacillus and Bifidobacterium and reduce growth of harmful bacteria like Closteridium and enteroccoci and harmful yeasts like Candida. Inulin feeding has been shown to reduce inflammation, malabsorption and diarrhea in patients with ulcerative colitis and irritable bowel syndrome. Animal studies have reported that feeding prebiotics like inulin and probiotics like Lactobacillus and Bifidobacterium can significantly reduce risk of colon cancer.