If you've been reading up on gut health, then you may have heard of inulin.
Inulin is a fiber that has been linked to several health benefits, and is added to many foods.
However, some people have concerns about its side effects and how well it works.
This article takes a detailed look at inulin and its health effects.
What is inulin?
Inulin is a type of soluble fiber found in many plants.
It is a "fructan" - meaning that it is made up of chains of fructose molecules that are linked together in a way that cannot be digested by your small intestine.
Instead, it travels to the lower gut, where it functions as a prebiotic, or food source for the beneficial bacteria that live there.
Your 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 a very long time, and some early humans consumed much more inulin than we do today (3).
While inulin is found in many plants, it also comes in supplement form, generally as a powder. This is what it looks like.
Bottom line: Inulin is a soluble fiber found in many plants. Your gut bacteria convert it into short-chain fatty acids, which provide several health benefits.
Where does inulin come from?
Inulin is naturally found in many plants, but can also be modified for commercial use.
Natural Sources of Inulin
Although many plants contain only small amounts of inulin, others are excellent sources. Here's how much inulin is in 3.5 oz, or 100 grams, of the following foods:
- Asparagus: 2-3 grams.
- Chicory root: 36-48 grams.
- Garlic: 9-16 grams.
- Jerusalem artichoke: 16-20 grams.
- Jicama: 10-13 grams.
- Onions: 1-8 grams.
- Yacon root: 7-8 grams
Manufactured sources of inulin
Inulin is also available in supplement form or as an ingredient in protein bars, cereal bars, yogurt and other products. Manufactured inulin comes in several forms (2):
- Native chicory: Extracted from chicory root.
- Oligofructose: Made by removing the longer molecules from inulin.
- HP: High-performance (HP) inulin is created by removing the shorter molecules from it.
- FOS: Fructooligosaccharides (FOS) consist of short inulin molecules synthesized from table sugar.
Bottom line: Inulin is found naturally in several foods. It's also modified for commercial use, and there are several varieties.
Health benefits of inulin
Improves digestive health
The gut microbiota is the population of bacteria and other microbes that live in your gut. This community is highly complex, and contains both good and bad bacteria.
Having the right balance of bacteria is essential for keeping your gut healthy and protecting you from disease (4).
Inulin can help promote this balance. In fact, studies have shown that inulin can help stimulate the growth of beneficial bacteria. Increasing the amounts of these bacteria can help improve digestion, immunity and overall health (1, 2, 5, 6, 7).
Bottom line: Inulin supports the growth of beneficial gut bacteria. This keeps the gut bacteria balanced and may have various health benefits.
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 (8).
In another 4-week study, older adults who were given 15 grams of inulin per day reported less constipation and better digestion (9).
That being said, several studies have found no effects on bowel frequency (10).
Bottom line: For many people, inulin can help relieve constipation by causing more frequent bowel movements and better stool consistency.
Promotes weight loss
When overweight and obese adults took 21 grams of inulin per day, their hunger hormone levels decreased and their fullness hormone levels increased (13).
On average, the people taking inulin lost over 2 lbs (0.9 kg), while the control group gained about 1 lb (0.45 kg) during the 12-week study.
In another weight loss study, people with prediabetes took inulin or another fiber called cellulose for 18 weeks. Those taking inulin lost 7.6% of their body weight, while the cellulose group lost only 4.9% (14).
Bottom line: Inulin and oligofructose supplements may help regulate appetite in adults, leading to weight loss.
Helps control diabetes
However, this may depend on the type of inulin, and 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 reducing fat in the liver can help reduce insulin resistance and potentially reverse type 2 diabetes (20).
In another study, women with type 2 diabetes were given 10 grams 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 10.5% (17).
Bottom line: HP inulin has been shown to reduce blood sugar levels in people with diabetes, but other forms may not be as beneficial.
Other potential benefits
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.
May support heart health
A human study found that women given 10 grams of HP inulin for 8 weeks experienced significant decreases in both triglycerides and LDL cholesterol (17).
However, other human studies reported less reductions in triglycerides, and no improvements in other markers.
Bottom line: Several studies indicate that inulin may improve certain risk factors for heart disease, but the evidence is mixed.
May improve mineral absorption and bone health
Bottom line: A few studies show that inulin may increase absorption of calcium and magnesium, and improve bone mineralization in children.
May help prevent colon cancer
It's thought that the fermentation of inulin into butyrate protects colon cells. For this reason, several studies have looked into the effects on colon health (30).
One review looked at 12 animal studies, and found that 88% of the groups given inulin saw a reduction in precancerous colon growths (31).
Bottom line: Animal studies have found that inulin can reduce gut inflammation and reduce the growth of precancerous cells. This may lead to a reduced risk of colon cancer, but more research is needed.
May help treat inflammatory bowel disease
Several animal studies suggest that inulin supplements may have benefits against inflammatory bowel disease (IBD) (34).
Nevertheless, researchers are not yet ready to recommend the use of inulin in treating IBD (37).
Bottom line: Inulin may also have benefits against inflammatory bowel diseases, including ulcerative colitis and Crohn's disease.
Safety and side effects
The different forms of inulin have been studied extensively, and appear to be safe for most people when consumed 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 have worsened symptoms after taking it. Additionally - and very rarely - people with a food allergy to inulin may experience an anaphylactic reaction, which can be dangerous (38).
If you take more than a small amount, then you're likely to experience some side effects in the beginning.
The most common side effects are:
For example, oligofructose (a type of inulin) has been shown to cause significant flatulence and bloating for people taking 10 grams per day (39).
Inulin from chicory root can generally be taken at higher dosages, but some people reported slight stomach discomfort at 7.5 grams a day (40).
You can minimize your risk of discomfort by slowly increasing your intake over time, which helps your body adjust.
Bottom line: Although inulin is safe for most people when taken at recommended dosages, people with certain allergies or a FODMAP intolerance should avoid it.
Dosage and how to take
Although all types of inulin are safe for most people, some are more likely to cause side effects.
Therefore, it's best to start slow. Begin by adding some inulin-rich foods to your diet on a regular basis.
If you decide to supplement, begin with no more than 2-3 grams a day for at least 1-2 weeks.
Then, slowly increase your intake by 1-2 grams at a time, until you're taking 5-10 grams a day. Most of the studies used 10-30 grams per day, gradually increasing over time.
The side effects should also improve with continued use. However, not everyone may be able to tolerate the amounts listed here.
Bottom line: Start by taking 2-3 grams a day for at least 1-2 weeks. Then gradually increase your dosage.
Should you take inulin?
Inulin has several important health benefits. It may promote gut health, help you lose weight and help manage diabetes.
However, while it is safe for most people, you should be careful if you have a FODMAP intolerance or certain allergies.
Additionally, start with a low dose of inulin and gradually increase your intake over the course of a few weeks.
Remember that if a little of something is good, more is not always better.