Inulin: Is This Commonly Used Fiber Additive Friend or Foe?

Ariel Harsinay


September 18, 2019

Inulin-Induced Digestive Discomfort

Many Americans consuming high levels of inulin may not know that they are doing so because labeling it is not required on processed food products, yet they may be experiencing the common side effects: cramping, bloating, and increased frequency of bowel movements. These symptoms tend to appear when alterations in diet cause a high fiber intake that was not previously present, and they subside as the body adjusts.[3] While natural sources of fiber are difficult to overconsume, diets centered on processed foods may leave some with resulting digestive discomfort.[2]

The amount of inulin that should be consumed depends on individual tolerance and goals. In adults with specific conditions, the following amounts are recommended[19]:

  • For those with diabetes: 10 g/day for 8 weeks

  • For weight loss: 10-30 g/day for 6-8 weeks

  • To lower high triglycerides: 14 g/day

  • To relieve constipation: 12-40 g/day for 4 weeks

Registered dietitians like Tamara Duker Freuman, MS, RD, CDN, whose work focuses on digestive and metabolic diseases, often recommend gradually building up a tolerance to inulin.

"There is no single food or ingredient that is so essential to good health that it is worth putting yourself through severe cramping or gas pain, and that includes inulin," she says. "For people who are able to tolerate it, including inulin-rich foods in the diet makes a lot of sense. Inulin is an objectively health-promoting type of fiber with particular prebiotic benefits, and it seems to aid in dietary calcium absorption as well." Natural sources of inulin are encouraged over manufactured forms, she adds.

William Chey, MD, a gastroenterologist from the University of Michigan, echoed the need to balance inulin's benefits and potential side effects.

"On the one hand, inulin is a form of soluble fiber that has prebiotic properties. On the other hand, inulin is universally nondigestible and nonabsorbable by the human small intestine," he says. "Depending upon the types of bacteria that are living in the bowel, this can lead to issues with gas, bloating, cramping, or even diarrhea, particularly in patients with irritable bowel syndrome who have underlying problems in gut motility and sensation. That said, there is emerging evidence to suggest that some people's GI symptoms can decrease over time with continued ingestion of inulin related to adaptation of the gut microbiome."

Next Steps

While the health benefits seem promising, bloating and discomfort owing to overconsumption remain a primary concern. And because food manufacturers are currently not required to specify the amount of inulin in their products, it can be difficult to know just how much we are consuming each day. In 2018, the US Food and Drug Administration officially classified inulin as a fiber on nutrition labels. However, if other sources of fiber are present in a food item, determining what percentage is from inulin, based on the label alone, is impossible.[2] Given its rising prominence, separately labeling the amount of inulin in foods may be coming soon, which could mitigate the adverse effects caused by overconsumption.[4]

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