What Is Inulin?

Inulin is a type of prebiotic, a compound that encourages the healthy growth of gut bacteria. Beneficial gut bacteria support gut health and immunity, as well as reduce disease risk. Inulin is also a type of fermentable fiber, meaning bacteria metabolize it in the large intestine.

Inulin is a type of oligosaccharide called a fructan. Fructans are a chain of fructose (sugar) molecules strung together. Inulin is found naturally in the roots of many foods, such as whole wheat, onions, garlic, and artichokes. It is commonly extracted from chicory root and added to foods.

This article explains inulin's uses and potential benefits and side effects. It also covers where to find inulin and how to incorporate it into your diet.

Uses of Inulin

Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian, pharmacist, or doctor. No supplement is intended to treat, cure, or prevent disease. 

Inulin is considered a functional food, which means it has a potential benefit on health. Some people incorporate inulin-containing foods and supplements into their diet to support gut health, manage blood sugar, control weight, and reduce cancer risk. Some of these uses have more evidence than others.

Gut Health

As a prebiotic, inulin can stimulate the growth of beneficial bacteria such as Bifidobacterium. Since increasing the number of good bacteria in your gut can help to decrease harmful bacteria, some research has focused on whether inulin could support gut health.

A 2020 meta-analysis published in the European Journal of Clinical Microbiology & Infectious Diseases looked at the effect of inulin on the gut microbiome. Most of the nine studies evaluated were randomized, double-blind, placebo-controlled trials.

The most consistent change researchers noted with inulin supplementation was an increase in Bifidobacterium. In addition, Anaerostipes, Faecalibacterium, and Lactobacillus (more types of health-promoting bacteria) increased, while Bacteroides ("bad" bacteria) decreased with inulin supplementation.

Another 2019 study published in The American Journal of Clinical Nutrition evaluated the effects of an inulin-rich diet on human gut health. The single-group trial included 26 healthy adults. For two weeks, participants ate a diet of 15 grams (g) of inulin-type fructans per day.

During the intervention, participants had increased Bifidobacterium, decreased Clostridiales, and a tendency to decreased Oxalobacteraceae ("bad" bacteria). In addition, during the trial, participants felt full longer and had fewer unhealthy food cravings. However, three weeks after the diet intervention, these changes were reversed.

Blood Sugar Control

Since low-fiber diets are a risk factor for type 2 diabetes, some research has evaluated whether inulin could affect insulin resistance (when your body doesn't respond to insulin as it should). Insulin is a hormone that regulates glucose (sugar) levels in the blood.

In a 2019 systematic review and meta-analysis published in the Journal of Diabetes Research, researchers evaluated the effect of inulin-type carbohydrates (ITCs) on insulin resistance in people with type 2 diabetes and obesity. The meta-analysis combined 11 randomized clinical trials (RCTs) and systematically reviewed another 14 RCTs. It included 634 participants who received either dietary ITC intervention or placebo.

The results showed that ITC intervention significantly decreased fasting plasma glucose, fasting insulin, HbA1c (blood sugar attached to hemoglobin), and homeostatic model assessment IR (an estimation of insulin resistance). However, it did not find that ITC supplementation reduced body mass index (BMI).

On the other hand, another 2021 study published in Nutrients examined whether inulin supplementation affected insulin sensitivity in adults with prediabetes (impaired glucose tolerance, a risk factor for developing type 2 diabetes). The randomized controlled trial included 24 participants at risk for type 2 diabetes.

Participants received either 10 g/day of inulin or a placebo for six weeks. The results showed that when a controlled diet stabilized body weight and composition, inulin supplementation did not improve peripheral insulin sensitivity.

Finally, in a systematic review and meta-analysis published in the European Journal of Clinical Nutrition, researchers evaluated the effect of inulin on blood lipids and glucose levels. In 20 RCTs with 607 adult participants, researchers found that inulin-type fructans (ITFs) reduced low-density lipoprotein cholesterol (LDL, "bad" cholesterol).

In addition, they found that supplementation with ITFs helped to lower fasting blood sugar, reduce fasting insulin, and improve good (HDL) cholesterol in people with type 2 diabetes.

Weight and Appetite Control

Fiber is the zero-calorie indigestible part of a carbohydrate. It helps to keep you full by slowing down the rate at which food empties from your stomach. Therefore, some research has centered on inulin's potential to control appetite.

In a 2017 randomized controlled trial published in The American Journal of Clinical Nutrition, researchers evaluated whether inulin supplementation could affect the appetites of children with excess weight and obesity. Researchers randomly assigned 42 children ages 7-12 with BMIs greater than the 85th percentile to 8 g of oligofructose-enriched inulin per day or placebo for 16 weeks.

Compared with placebo, the inulin group had significantly higher feelings of fullness and lower food consumption at 16 weeks. In addition, supplementation significantly reduced energy intake at 16 weeks in 11- and 12-year-olds but not in 7- to 10-year-olds.

The verdict was mixed in another systematic review conducted on randomized control trials featuring adolescents and adults. The study included four pediatric RCTs and 15 adult RCTs. In infants, limited evidence showed no effect of ITF supplementation on body weight. However, in non-obese adolescents, after one year of supplementation, participants had a reduced increase in body weight and BMI.

In adults, results were inconsistent. For example, one small RCT found significant differences in appetite and energy between experiment and control groups, while all other studies found no significant effect of supplementation.

Other

Some people also use inulin for the following:

• Colorectal cancer prevention
• Calcium absorption
• Heart health

There is little evidence to support inulin for these uses, but research is ongoing.

What Are the Side Effects of Inulin?

Your healthcare provider may recommend taking inulin for gut health, diabetes, insulin resistance, or appetite control. However, consuming a supplement like inulin may have potential side effects. These side effects may be common or severe. 

Common Side Effects

The FDA has categorized inulin as "generally recognized as safe" (GRAS). However, inulin can cause gastrointestinal side effects, including:

• Diarrhea or increased bowel movements
• Bloating
• Flatulence (gas)
• Abdominal cramping

To reduce experiencing these side effects, talk to a healthcare provider before beginning inulin supplementation. In addition, start slow and stay hydrated.

Severe Side Effects

If you have a pollen allergy, you should be careful with consuming chicory root. Some evidence indicates that chicory may produce oral allergy syndrome (OAS) in some people. OAS is a cross-reaction with an inhaled allergen that can cause mouth itching. In 2003, researchers suggested adding chicory to the list of foods that can cross-react with birch pollen and cause OAS symptoms.

In addition, chicory is part of the Asteraceae plant family. These plants also include sunflowers, dahlias, daisies, chamomile, and dandelion. Therefore, if you are allergic to these pollens, you should avoid inulin derived from chicory root because it belongs to the same family.

Anaphylaxis, a severe allergic reaction, is rare. However, since it can occur in any allergy without warning, it's good to know the signs, which include:

• Itching
• Rash
• Swelling
• Wheezing
• Difficulty breathing
• Unconsciousness

Anaphylaxis is a life-threatening medical emergency. Therefore, any symptoms warrant immediate medical attention.

Precautions

Many people with irritable bowel syndrome (IBS) benefit from eating a low FODMAP diet. A low FODMAP diet restricts certain types of carbohydrates. These carbohydrates include fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (hence the acronym FODMAP).

Therefore, if you follow a low FODMAP diet, you will likely need to avoid inulin, since it is a fermentable oligosaccharide. However, you may be able to add it back into your diet if you find out it is not an offender for you. Working with a registered dietitian specializing in this type of dietary regimen is the best way to navigate such a scenario.

As with any medication or supplement, discuss supplementation with a healthcare provider first if you are pregnant or lactating.

Dosage: How Much Inulin Should I Take?

Always speak with a healthcare provider before taking a supplement to ensure that the ingredients and dosage are appropriate for your individual needs. 

According to the U.S. Department of Agriculture (USDA), you should get between 25 to 36 grams of fiber daily (or 14 grams for every 1,000 calories per day). However, more than 90% of Americans fail to meet this recommendation.

There is no recommended dosage for inulin supplements. In some research, participants consumed 8 to 10 g of inulin. Many available supplements contain 2 to 3 g of inulin.

What Happens If I Take Too Much Inulin?

To avoid toxicity, be aware of the appropriate dosage (above) and keep the upper limit in mind. According to the FDA, studies have found no significant adverse effects in healthy adults who consumed as much as 40 grams of inulin per day. At high doses (greater than 40 grams), gas and loose stools are the most common adverse effect.

If you consume more than this amount or more than what is recommended by a healthcare provider, you may want to seek medical attention. 

How to Store Inulin

Foods rich in inulin should be stored using best practices for preventing spoilage. For example, most inulin-containing foods do best in a cool, dry place away from sunlight.

Also store inulin supplements in a cool, dry place, and keep them away from direct sunlight. Discard after one year or as indicated on the packaging.

Similar Supplements

Some similar supplements include other prebiotics and fibers, such as:

• Psyllium
• Galactooligosaccharides (GOS)
• Fructooligosaccharides (FOS)
• Resistant starch
• Wheat dextrin
• Fine wheat bran

Talk to a healthcare provider to determine which type of prebiotic or fiber supplement is right for you.

Sources of Inulin

Inulin is widely available in food, which is the best way to get inulin because the body more readily absorbs nutrients through food sources.

When you want to increase your fiber intake, it's always a good idea to eat whole foods like fruits, vegetables, whole grains, nuts, seeds, and legumes. Eating many different foods will ensure that you include all different types of fibers in your diet and reduce the chance of adding unwanted sodium and sugar.

In addition to food sources, inulin is available as a supplement.

Food Sources of Inulin

If you are looking for foods that contain inulin specifically, you can find a good amount in:

• Wheat
• Asparagus
• Leeks
• Onions
• Garlic
• Chicory
• Oats
• Soybeans
• Artichokes

In addition to whole food sources, food companies also add inulin to processed foods. Inulin has no calories and can function as a fat substitute in margarine and salad dressings. In baked goods, it may be used to add fiber and can substitute for some flour without affecting taste and texture. If you are looking for a food with added inulin, the label will likely list "inulin" or "chicory root fiber" as an ingredient.

Good ways to ensure you are eating a wide range of fibrous foods include:

• Aim to eat at least one fruit or vegetable at every meal.
• Try to eat at least three servings of whole grains daily, such as whole-grain bread, oats, quinoa, barley, bulgur, brown rice, farro, and wheat berries.
• Eat a serving of nuts or seeds daily.
• Make half of your plate non-starchy vegetables.
• Snack on fiber-rich foods like whole-grain air-popped popcorn, carrots with hummus or guacamole, and whole fruit with nut butter.
  

Currently, the FDA is working to ensure that the types of dietary fibers added to foods provide health benefits. It has provisionally approved inulin as one of these fibers.

Inulin Supplements

Inulin supplements are available in various forms, including:

• Powders
• Chewables (like gummies)
• Capsules

Often, inulin supplement labels may list the product as a "prebiotic," or state that it is used for "intestinal health" or "weight control." However, keep in mind that the FDA does not regulate supplements.

Most inulin supplements provide around 2 to 3 g of fiber per serving. When using a supplement, calculate your total fiber consumption through food sources and supplements to ensure you stay in the recommended range.

Inulin supplements may be extracted from artichokes, agave, or chicory root. If you have allergies to any sources, read labels carefully for those and other potential allergens, like wheat or egg.

Before starting any supplement, consult with your healthcare team. When adding fiber sources like inulin to your diet, you should do so slowly and drink adequate amounts of fluid to prevent constipation, gas, and bloating.

Summary

Inulin is a fermentable prebiotic fiber beneficial for a healthy gut microbiome. Some research supports its use for gut health, blood sugar control and diabetes, and appetite management. People also use inulin for cancer prevention and heart health, but there is less evidence to support those uses.

The FDA considers inulin a generally recognized as safe, or GRAS, food. However, side effects from larger doses may include gas and loose stools. In some cases, people who have certain pollen allergies may have allergic reactions to inulin from chicory root.

Onions, garlic, artichokes, leeks, wheat, and oats naturally contain inulin. Supplements are usually derived from chicory root.