What to know about inulin, a healthful prebiotic

Inulin is a dietary fiber that may benefit gut health. Plants naturally contain inulin, and some manufacturers add it to processed foods.

Articles about gut health often talk about inulin, but some people have concerns about its side effects and how well it works.

This article takes a detailed look at inulin and its effects on health.

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Inulin is a type of soluble fiber found in many plants.

Inulin is also fructan. Like other fructans, it is a prebiotic, meaning that it feeds the good bacteria in the gut.

Fructans are chains of fructose molecules. The molecules link together in a way that the small intestine cannot break down. Instead, they travel to the lower gut, where they feed beneficial gut bacteria.

The gut bacteria convert inulin and other prebiotics into short-chain fatty acids, which nourish colon cells and provide various other health benefits (1).

Plants containing inulin have been around for thousands of years, and some early humans consumed much more inulin than we do today (2).

Manufacturers add inulin to processed products to (3):

• boost the prebiotic content of foods
• replace fat in foods
• replace sugar in foods
• alter the texture of foods
• improve the health benefits of foods due to its benefits for gut health

Inulin naturally occurs in many plants, but manufacturers can also modify it for commercial use.

Natural sources

Inulin occurs in around 36,000 species of plants, and researchers say that chicory roots are the richest source (3).

Many plants contain only small amounts of inulin, while others are excellent sources.

Here’s how much inulin is in 3.5 ounces (oz), or 100 grams (g), of the following foods (4):

• chicory root, 35.7–47.6 g
• Jerusalem artichoke, 16–20 g
• garlic, 9–16 g
• raw asparagus, 2–3 g
• raw onion pulp, 1.1–7.5 g
• wheat, 1–3.8 g
• raw barley, 0.5–1 g

Manufactured sources

Inulin is also available in supplement form or as an ingredient in:

• protein bars
• cereal bars
• yogurts and other milk products
• drinks
• baked goods
• desserts

Manufactured inulin comes in several forms (5):

• Chicory inulin: Extract from chicory root.
• High-performance (HP) inulin: Manufacturers create HP inulin by removing the shorter molecules from it.

Fiber supplements that are closely related to inulin are fructooligosaccharides, also known as oligofructose.

People take inulin for a variety of reasons. It may improve digestive health, relieve constipation, promote weight loss, and help control diabetes.

Improves digestive health

The gut microbiota is the population of bacteria and other microbes that live in the gut. This community is highly complex and contains both good and bad bacteria.

Having the right balance of bacteria is essential for keeping the gut healthy and protect the body from disease (6).

Inulin can help promote this balance. In fact, studies have shown that inulin can help stimulate the growth of beneficial bacteria (1).

Increasing the amounts of healthful bacteria can help improve digestion, immunity, and overall health.

Relieves constipation

For many people, inulin may also help relieve symptoms of constipation.

One analysis found that people taking inulin experienced more frequent bowel movements and improved stool consistency (7).

In another 4-week study, older adults who consumed 15 g of inulin per day reported less constipation and better digestion (8).

Promotes weight loss

Several studies indicate that inulin can also help with weight loss (9, 10).

In one weight loss study, people with prediabetes took inulin or another fiber called cellulose for 18 weeks. Those taking inulin lost significantly more weight between 9 and 18 weeks (10).

However, some studies of children with overweight or obesity have not found that oligofructose or inulin reduce calorie intake (11, 12).

Helps control diabetes

Several studies suggest that inulin may improve blood sugar control in people with diabetes and prediabetes (10, 13, 14).

However, this may depend on the type of inulin. The high-performance (HP) type may be especially beneficial. For example, one study found that HP inulin decreased fat in the livers of people with prediabetes (14).

This is significant, as some research says that reducing fat in the liver can help reduce insulin resistance and potentially reverse type 2 diabetes (15).

In another study, females with type 2 diabetes consumed 10 g of HP inulin per day. Their fasting blood sugar decreased by an average of 8.5%, while hemoglobin A1c — a marker for long-term blood sugar control — fell by an average of 10.4% (16).

However, although HP inulin may benefit diabetes and prediabetes, results from older studies using some other types of inulin are less consistent (17, 18, 19).

Improved mineral absorption and bone health

Animal studies have found that inulin improves calcium and magnesium absorption, resulting in improved bone density (20, 21).

Human studies have found similar benefits. According to a Food and Drug Administration (FDA) review, scientific evidence supports the idea that inulin-type fructans can benefit bone mineral density and how well the body absorbs calcium (22).

There is some evidence that inulin supplements may help other conditions, although the evidence is not as strong.

This includes benefits for heart health, mineral absorption, colon cancer, and inflammatory bowel disease (IBD).

May support heart health

Inulin may improve several markers for heart health.

In one study, females who received 10 g of HP inulin for 8 weeks had significant decreases in both triglycerides and low-density lipoprotein (LDL) cholesterol (16).

However, other studies have reported smaller reductions in triglycerides, and no improvements in other markers.

May help prevent colon cancer

Some researchers think that inulin could help protect the cells in the colon. This is because of how inulin ferments into butyrate. For this reason, several studies have looked into its effects on colon health (23).

One review looked at 12 animal studies and found that 88% of the groups that received inulin saw a reduction in precancerous colon growths (24).

In another study, inulin-fed rats showed fewer precancerous cell changes and less inflammation than the control group (25).

An older study on humans found that inulin caused the colon environment to be less favorable for cancer development, which is promising (26).

This may lead to a reduced risk of colon cancer, but more research is needed.

May help treat IBD

Research suggests that inulin, as a prebiotic, can have benefits for inflammatory bowel disease (IBD) by improving gut flora and decreasing inflammation in the gut (27).

A few small human studies have also found reduced symptoms of ulcerative colitis, and a reduction in inflammatory markers in Crohn’s disease (28, 29).

Nevertheless, researchers are not yet ready to recommend the use of inulin in treating IBD (30).

Researchers have studied the different forms of inulin extensively, and it appears to be safe for most people in small doses.

However, people who are intolerant to FODMAPs are likely to experience significant side effects.

Those who are allergic to ragweed may also experience worsened symptoms after taking chicory inulin. Additionally — and very rarely — people with a food allergy to inulin may experience anaphylaxis, which can be life-threatening.

When adding inulin to the diet, start with small amounts. Larger amounts are more likely to trigger side effects. Increasing intake slowly over time will help the body to adjust.

The most common side effects are:

• flatulence (gas)
• bloating
• abdominal discomfort
• loose stools and diarrhea

For example, studies have shown that oligofructose — which is related to inulin — can cause significant flatulence and bloating for people taking 10 g per day (31).

People can generally take inulin from chicory root at higher dosages, but some people reported slight stomach discomfort at 7.8 g a day (32).

Although all types of inulin are safe for most people, some are more likely to experience side effects.

When adding inulin to the diet, start with small amounts. Begin by adding small amounts of inulin-rich foods to the diet regularly.

When starting to take inulin supplements, some sources suggest beginning with no more than 2–3 g a day for at least 1–2 weeks. Slowly increase this before reaching 5–10 g a day.

Most studies into inulin use 10–30 g per day, gradually increasing the amount over time.

Any side effects should improve with continued use. However, not everyone can tolerate the amounts listed here.

Inulin has several potential health benefits. It may promote gut health, help with weight management, and help manage diabetes.

That said, scientists need to do more high quality research before they can know the actual health effects of inulin in the human body.

While it is safe for most people, those with a FODMAP intolerance or certain allergies should be cautious.

When adding inulin to the diet, people should start with a low dose and gradually increase their intake over a few weeks.

Inulin is widely available as a supplement in health food stores and online.