What Is Inulin Fiber?

Chicory Root is a Good Source of Inulin Fiber
Chicory is a Good Source of Inulin

Inulin or inulin fiber, as it is also known, is a carbohydrate. It is made up of a small number of linked sugar molecules and is therefore classed as an oligosaccharide. This term is derived from the Greek words oligos, meaning few and sacchar, which means sugar. This oligo-saccaride is largley undigested by the human digestive tract and inulin is thus also considered to be a fiber.

Where Can I Find It?

Inulin occurs naturally in many plants, which use it as a means of storing energy. High levels of inulin are typically found in the storage organs of plants, the roots. Those plant roots, which we eat as vegetables, can therefore be particularly good sources of inulin. These include:

  • Chicory root
  • Sunchoke (Jerusalem artichoke)
  • Burdock root
  • Wild Yam

Many other plants also smaller amounts of inulin:

  • Onion
  • Garlic
  • Leeks
  • Asparagus
  • Salsify
  • Bananas
  • Wheat
  • Rye

The following herbs also contain inulin:

  • Dandelion root
  • Elecampane root
  • Chinese herb codonopsis

Be aware though that the inulin levels in all these natural sources will fluctuate depending on the season, harvest time and storage method.

Inulin is also often added in varying amounts as a fiber supplement, a prebiotic and even a sweetener to a wide range of processed foods from dairy products and infant formula to cereals and meal-replacement bars.

A large percentage of probiotic supplements also contain inulin for its prebiotic qualities. Most of this commercial inulin is extracted from chicory root. Take a look at the labels of your processed foods and especially your probiotics to see they contain this prebiotic food and fiber supplement.

The Evidence for Inulin Fiber

As a prebiotic, inulin is not digested by the small intestine and so arrives unaltered in the colon, where it serves as food for our beneficial bacteria.

Numerous scientific studies have shown that this prebiotic does indeed increase the numbers of beneficial bacteria, mainly those belonging to the bifidobacterium genus (family) of organisms1,2,3,4. These bifidobacteria are particularly useful to us, as they:

  • Manufacture B vitamins for our use.
  • Help with the functioning of the liver.
  • Produce lactic and acetic acids, which increase the acidity of the colon, making it less attractive for those alkaline-loving harmful bacteria.
  • Inhibit bacteria, which form nitrates in the bowel. Nitrates have been linked to cancer in many scientific studies.

As well as helping our all-important bifidobacteria populations, the consumption of inulin has also been shown to:

  • Reduce constipation.
  • Inhibit the growth of harmful bacteria including clostridia and E. Coli5.

It seems then that inulin fiber is very beneficial. But before you make your decision to take it, read on to learn about the other side of inulin....

The Evidence against Inulin Fiber

Inulin clearly serves as an energy source for our good bacteria, feeding them and ensuring they thrive. Unfortunately though, inulin fiber appears not only to feed good bacteria. It can also feed bad!!! If you know you have an unbalanced digestive flora or have symptoms of food intolerance or intestinal dysbiosis inulin fiber may feed your “bad bacteria” as well as your good. If this is you, then perhaps inulin is best left alone. For this reason, Professor John Hunter, Gastroenterologist at Addenbrookes Hospital, Cambridge, UK, advises his food intolerance patients to avoid inulin6.

Should I Try Inulin?

Confused About Whether or Not to Take Inulin Fiber?

It’s clear that the jury is out regarding inulin fiber. Clearly it has proven health benefits but it also has some disadvantages....

So...if you decide to try inulin fiber, be sure to consult your physician before you begin.

Be aware too that inulin works in conjunction with probiotics, so be sure to take a probiotic too. Begin with a small quantity only and be prepared for a temporary increase in gas and bloating. Remember to listen to your body. If the exacerbation of your symptoms persists, then it is possible that inulin is not for you.

Good luck!


1.Gibson, G.R. et al; Selective Stimulation of Bifidobacteria in the Human Colon by Oligofructose and Inulin; Gastroenterology; 108: 975-982

2.Jenkins J.A. et al; Inulin, Oligofructose and Intestinal Function; Journal of Nutrition; 1999;129:1431S-1433S

3.Kleeson B. et al; Effects of Inulin and Lactose on Fecal Microflora, Microbial Activity and Bowel Habit in Elderly Constipated Persons; American Journal of Clinical Nutrition; 1997; Vol 65, 1397-1402

4.Roberfroid M.B et al; The Bifidogenic Nature of Chicory Inulin and its Hydrolysis Products; Journal of Nutrition; 1998; 128:11-19

5.Cartwright P.; Probiotics for Crohn's and Colitis; Prentice Publishing; Ilford; 2003

6.Hunter J O et al; The Management of Multiple Food Intolerance, Foods Matter, 2009

Return from Inulin Fiber to Prebiotics

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