Most reviews for Fiber One Chewy bars appear united that the Chicory Root Extract causes great amount of flatulence.

For example:

Tasted good but had no idea why I suddenly had such painful and relentless gas. This is not normally an issue with me. When I read the label I didn't see anything that seemed like it would cause such a problem. Then I realized that the first ingredient on the list was something I didn't recognize: Chicory Root Extract. I Googled it and discovered that it is actually a mild laxative and well known for causing terrible gastric issues.

Are these claims exaggerated or is Chicory Root Extract indeed known to cause such symptom?

  • 100% true. But not for everyone. “Your small intestine does not absorb inulin. When it reaches your large intestine (colon), bacteria ferment it.” webmd.com/vitamins-and-supplements/inulin-uses-and-risks Ergo smelly fermentation farts and painful gas. Any product that contains inulin really. Jerusalem artichokes/Sunchokes (fartichokes), Quaker Oats Granola, Kashi Go cereals, and many more.
    – Brian D
    Apr 21, 2020 at 5:39

3 Answers 3


Chicory root extract is a dietary supplement/food additive which is used as a source of soluble fiber produced by mixing dried, ground chicory root with water. Fresh chicory root contains 68% inulin (fructans), 14% sucrose, 5% cellulose, 6% protein, 4% ash, and 3% other compounds while dried chicory root extract contains approximately 98% inulin (fructans) and 2% other compounds.

Per Brian E. Lacy in 2011, due to absence of large, randomized, controlled studies performed in patients with functional bloating, research data obtained from patients with irritable bowel syndrome show that avoiding food products that readily ferment within the colon such as fructans and fiber improved bloating.

A careful dietary history should be taken from each patient, with an emphasis on food products that readily ferment within the colon (eg, dairy, fructose, fructans, fiber, and sorbitol). A recent study showed that bloating improved in IBS patients who avoided these fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. Gastroenterologists usually direct patients to remove one possible offending substance at a time (ie, dairy first, then fructose-containing liquids, then fiber, and so on). Some patients have noted symptom improvement after minimizing carbohydrates and gluten, although this approach has not been well studied.


Chicory contains inulin, a type of fiber classified as a fructan. A large body of research implicates fructans, alongside other carbohydrates that ferment in the colon, in irritable bowel syndrome. The acronym researchers have chosen for this is FODMAPs(fermentable oligosaccharides, disaccharides, monosaccharides and polyols). Mechanisms and efficacy of dietary FODMAP restriction in IBS (Staudacher et al. Nature Reviews Gastroenterology & Hepatology 2014) says:

The inulin-type fructans are a major dietary source of fermentable carbohydrates. They are either linear or branched fructose oligosaccharides that include inulin, (DP 2–60), oligofructose (DP 2–8) and fructo-oligosaccharides (<10 DP).50 Minimal digestion of fructans occurs in the small intestine51 due to the absence of enzymes in the human gastrointestinal tract that are able to digest the β-(2–1) fructosyl–fructose glycosidic bonds.

Fructans are present as storage carbohydrates in plants.52, 53, 54, 55 Most dietary fructans are obtained from wheat and onion,54, 56 which are fairly low in fructans but are consumed in large quantities. Commercial fructans derived from sucrose or chicory root are increasingly added to pre-prepared foods due to their textural and sensory properties and potential health benefits, including their low-energy content.57 Fructans are also prebiotic, as they are “nondigestible, fermentable compounds that lead to selective stimulation of growth and/or activity of one or a limited number of microbial genera/species in the gut microbiota that confer health benefits to the host”

Limited trials of inulin have shown it can worsen IBS symptoms. Dietary Triggers of Abdominal Symptoms in Patients With Irritable Bowel Syndrome: Randomized Placebo-Controlled Evidence tested inulin itself, though there are more trials on the fructans in wheat.

However for average people, most trials show inulin from chicory is well-tolerated., though Gastrointestinal Tolerance of Chicory Inulin Products shows " inulin fibers tended to increase GI symptoms mildly. Most frequently reported symptoms were flatulence followed by bloating" and Fn-type Chicory Inulin Hydrolysate Has a Prebiotic Effect in Humans found " one case of increased flatulence, three cases of intestinal distension and two cases of cramps in the intestine" in a trial of 8 people.

  • I think a good answer should also explain that soluble fibre is more prone for bad odour flatulence than insoluble fibre, which may often cause flatulence with no smell. (I mean, is it?)
    – cnst
    Nov 20, 2015 at 0:14
  • @cnst I don't think you're understanding what this answer means. This answer is stating that inulin can cause gas/bloating in people with IBS. Chicory is a source of inulin. This answer makes no claim regarding dietary fiber and bloating/gas; they are unrelated.
    – user70848
    Nov 24, 2015 at 3:09

High fiber foods, such as these Fiber One bars, are known to cause excess gas and other intestinal issues. The gas you and others may experience from eating these bars could be due to the high amounts of fiber in each bar. You can read the side of the box, via that Amazon link, to see how much fiber is in each bar (35% DV).

In addition, chicory root is a natural source of inulin, which is also associated with gas/bloating for people.

So not only is chicory root extract a good source of dietary fiber, which is itself associated with digestive side-effects like gas/bloating, it is also a natural source of inulin which is also associated with gas/bloating.

Short Answer/Summary

  • Chicory root extract, like whole grains and beans, is a source of dietary fiber
  • Chicory root is a natural source of inulin, like garlic and bananas
  • Sudden increases in fiber is a source of digestive problems
  • Sudden increases in inulin can be a source of gas/bloating
  • Reduce negative side effects of dietary fiber and/or inulin-rich foods by increasing them slowly in your diet while your body adjusts
  • Experts advise drinking extra water to help the fiber pass through the system

Regarding Fiber

SF Gate writes:

Some high-fiber foods may lead to uncomfortable bloating and gas. This is a natural side effect as the bacteria in your intestinal tract work to help fiber pass through. Reduce your chances of having gas by limiting certain types of foods or taking an over-the-counter supplement to prevent gas. and Consuming too much fiber at one meal or suddenly increasing your fiber intake may increase uncomfortable gas and bloating in your gut. Reduce this uncomfortable effect by slowly increasing your fiber intake over a period of days or weeks. This gives the natural digestive flora in your gut ample time to adjust to the increase in fiber http://healthyeating.sfgate.com/ease-gas-eating-fiber-2694.html

Additionally, Everyday Health (EH) notes:

Unfortunately, when you start to include more fiber-rich foods in your diet, you may start to notice an undesirable side effect: excessive gas. Flatulence and bloating can result, which can be embarrassing and uncomfortable, to say the least.

Livestrong also notes:

If, however, you eat more fiber than you are accustomed to, it can cause gas and bloating.... Eating a lot of fiber in one sitting, even if you normally consume a fair amount of fiber, can also cause gas. (emphasis added)

The University of Maryland Medical Center notes:

Fiber can cause gas and bloating.... Add fiber gradually over a period of a few weeks to avoid stomach distress. Water helps fiber pass through the digestive system. Drink plenty of fluids (about 8 glasses of water or noncaloric fluid a day).

The Harvard School of Public Health notes:

Experts recommend increasing fiber intake gradually rather than suddenly, and because fiber absorbs water, beverage intake should be increased as fiber intake increases.

** Regarding Chicory ** Specifically for chicory root, Wikipedia states that chicory root is a natural source of inulin, which is type of carbohydrate. Extracted chicory root is commonly used by food manufacturers in such things as breakfast bars because of it's smooth texture as a carbohydrate fiber - it's a way to add fiber without changing the taste or texture of the food. Inulin can also be found naturally in bananas, onions, and garlic.

Dr. Weil on Chicory and Fiber:

The only problem with inulin may be that it doesn't have the texture or taste of fiber. This can make it easy to consume too much, bringing on the same kind of digestive problems caused by an excess of any fiber: gas/bloating, nausea, flatulence, stomach cramping, diarrhea, constipation and digestive "rumbling."

As Wikipedia states

Inulins are a group of naturally occurring polysaccharides produced by many types of plants, industrially most often extracted from chicory.... Inulin-containing foods can be rather gassy, in particular for those unaccustomed to inulin, and these foods should be consumed in moderation at first...

  • 1
    No parts of this answer attempt to reference any scientific sources! Moreover, you're giving a bad name to all "fibre" period, whereas it's only the soluble fibre that truly deserves the bad name.
    – cnst
    Nov 18, 2015 at 22:19
  • 1
    Welcome to Skeptics! These are very unreliable references. Livestrong often appears in questions because people don't trust it. Please link to some empirical results supporting your claims.
    – Oddthinking
    Nov 19, 2015 at 1:26
  • Where does the Skeptics meta specifically require "scientific sources"? Just because someone doesn't trust Livestrong does not disqualify it from being a reference - Livestrong isn't banned.
    – user70848
    Nov 19, 2015 at 22:11
  • No, it isn't banned. Your answer hasn't been deleted. But it is earning downvotes, and I expect it will continue to until you fix it with references with empirical data.
    – Oddthinking
    Nov 19, 2015 at 22:43
  • 1
    I've never heard of anyone smelly farting from almonds; the picture of almonds on Livestrong is completely inappropriate, and a good reason to discard it as a source (I've never heard of it before, but now I know that it's not a site to be trusted) -- most fibre in almonds is insoluble fibre, which does not ferment in the colon the way inulin does.
    – cnst
    Nov 19, 2015 at 22:50

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