This soluble fiber is gaining popularity, but not all sources are created equal.

Christine Byrne
August 14, 2020
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What Is Inulin?

If you're in the habit of reading food labels, you may have noticed inulin listed as an ingredient on packaged food items and wondered what it was. In a nutshell, inulin is fiber. It can help you feel satisfied after eating and might help control your blood sugar levels. It's found naturally in certain foods and is added to others to increase the fiber content and help with texture. Let's dig a little deeper into how inulin works, where you can find it and its potential health benefits.

Inulin is a soluble fiber and a fructan

You likely already know that fiber is good for you. In fact, the Dietary Guidelines for Americans recommend that adults get 25 to 38 grams per day, as there's significant evidence to show that getting adequate fiber can help reduce the risk of diabetes, heart disease and certain cancers. It can also help with diabetes management and healthy bowel movements.

More specifically, inulin is a type of soluble fiber. "Soluble fiber is able to hold onto water and in turn gels up and turns viscous," says Amy Kimberlain, RDN, a spokesperson for the Academy of Nutrition and Dietetics. (Think of the thick texture of oatmeal or the creamy texture of bananas, both of which are rich in soluble fiber.) "Soluble fibers additionally slow down the transit time in digestion, which can lead to satiety as well as a possible benefit in helping to manage blood sugar levels," Kimberlain says.

While getting plenty of soluble fiber is a good thing, inulin is also classified as a fructan, which is a prebiotic fiber that ferments in your gut and feeds the good bacteria. While this is usually a good thing, eating too much inulin or other prebiotic fiber at one time can lead to too much fermentation, which in turn causes uncomfortable gas and bloating.

Inulin has some unique health benefits

Because soluble fiber can hold onto water and gel things up, inulin can help with constipation. "It has been shown to make stools softer, as well as possibly increase the number of stools per day," Kimberlain says. There's also evidence that inulin can be helpful in diabetes management, as it "may possibly improve blood sugar levels (in the short-term) as well as help [reduce] insulin resistance when inulin is taken along with a patients' diabetes medications," Kimberlain says. Note: It's a little confusing that the spelling of the fiber (inulin) is so close to that of the hormone (insulin).

Another possible benefit: as with other soluble fibers, inulin might help lower LDL cholesterol levels (the unhealthy kind) by binding to these triglycerides in your bloodstream.

And just a side note: Possible side effects (common when consuming a high-fiber diet) include abdominal pain, flatulence, bloating and possible belching, so someone with IBD would want to steer clear of products with this added in.

Inulin is found naturally in plant foods

Even if you've never heard of inulin, chances are you've eaten it before. Here are a few natural food sources:

  • Jerusalem artichokes

  • Jicama

  • Asparagus

  • Onion

  • Leeks

  • Garlic

  • Bananas (unripe)

  • Chicory root

In addition to inulin fiber, these plant foods also contain important vitamins and minerals. Kimberlain recommends adding these foods to your diet (or eating them more often, if they're already staples) if you're hoping to reap the health benefits of inulin.

Inulin improves taste, texture and fiber content of processed foods

"There are many reasons why inulin is added to products," Kimberlain says. For starters, it has a naturally sweet taste, which means it can add some sweetness to products without adding any calories. Secondly, inulin can add creamy texture and some bulk to packaged foods like yogurt, protein drinks and powders, and sugar-free desserts like chocolate or ice cream, again without adding any calories. It's also cheap, which makes it attractive to food manufacturers.

Prioritize naturally fiber-rich foods over added inulin

While added inulin isn't unhealthy, Kimberlain warns of the "health halo" effect. "Many products sell based on how they're marketed," she says. Added inulin means more grams of fiber on the nutrition label, and maybe a high-fiber claim on the front of the packaging. "It creates the idea that if it has fiber, it must be healthier," she says. However, packaged foods with added inulin are usually lacking in the vitamins and minerals that whole-food fiber sources provide. "I always recommend food first (in its natural form) when possible," Kimberlain says. That is, eating a diet rich in high-fiber foods like fruits, vegetables, whole grains, beans, legumes, nuts and seeds.

If it's impossible to get enough fiber from whole foods, taking an inulin supplement could help with constipation, blood sugar control and possibly lowering LDL cholesterol. However, getting too much inulin (which is much easier to do when you take supplements or eat enriched products) can lead to gas and bloating, and can also worsen symptoms for people with irritable bowel disease, irritable bowel syndrome or other GI issues.

Bottom line: Inulin is great, but there's no need to overdo it

You can reap all of the potential benefits of inulin by eating a few servings each week of inulin-rich whole foods. If you want to try a supplement that's up to you, but be aware that too much inulin can lead to uncomfortable side effects.