What Is Inulin? | Benefits, Dosage & Side Effects

Inulin is a supplement that you may have only recently heard of, or not at all. Inulin has recently taken centre stage with its appearances in BBC documentaries which sparked new investigations within scientific literature.

Inulin’s time in the spotlight is no surprise, as this soluble fibre is said to have a whole host of health benefits including improvements in blood sugar control, weight management, and digestive health.

So, what do the facts say? Here, we take a look at inulin in more detail, investigating the evidence for its use, and the variety of ways it can be added to your diet.

What is inulin?

Inulin is a type of soluble fibre commonly found in a variety of vegetables. It belongs to a class of carbohydrates known as fructans, meaning that they’re made up of fructose molecules that are specifically linked together to prevent digestion within the small intestine. Instead of being digested, inulin travels to the gut, where it acts as a prebiotic. Prebiotics help to feed and increase the number of good bacteria within our digestive system.

Is inulin classed as a fibre?

Inulin is a low-calorie soluble fibre containing 1.5 calories per gram. Although inulin is a form of carbohydrate, given it is made up from fructose molecules, it contains significantly fewer calories than carbohydrates as the fibre can’t be broken down or absorbed by the digestive system. When consumed, soluble fibre absorbs water and subsequently turns into a gel-like substance.

Health benefits of inulin

Feeling forever hungry along every step of your weight loss journey? Inulin has been regularly shown to help achieve your weight loss goals by helping to regulate your appetite and reduce those common feelings of hunger. ^{(1, 5, 13, 14)}

Inulin works by making changes to specific hormones that control your appetite levels, and helps to reduce the number of calories you eat by decreasing your feelings of hunger — and the results appear quite impressive. For example, studies have shown that individuals are able to lose between 1-6 kg across 12-18 weeks through the addition of inulin powder to their diet. ^{(5, 14)}

Not only are these individuals potentially able to reduce their body weight with the addition of inulin powder, but they’re also able to reduce ectopic fat storage. ⁽⁵⁾ Ectopic fat relates to fat that is stored within other areas of the body, such as the liver and muscle tissue.

Inulin could help to improve blood sugar levels in those with type II diabetes or pre-diabetes. ^{(3, 4, 6)} This is important as spiralling blood sugar levels can lead to a number of other metabolic disorders and ill health. One of the ways inulin does this is by reducing the amount of fat stored within the liver which may help improve our sensitivity to a hormone called insulin. ⁽⁹⁾

Insulin is a key hormone in controlling blood sugar levels as it helps to remove glucose from the blood into the liver or muscle where it can be stored for energy later. So, if inulin can improve sensitivity to insulin, we become more efficient at removing glucose from the blood and have better control over our blood sugar levels in the long term.

The large intestine is home to more than 400 kinds of bacteria that are commonly referred to as being either ‘good’ or ‘bad’ bacteria. High quantities of certain bacteria are important for our health, but imbalances can also lead to disease.⁽¹⁶⁾

Inulin plays an important role in keeping this balance in check by working as a prebiotic which help to feed and increase the number of these good bacteria. Keeping these ‘good bacteria’ within the body is important as they play a key role in digesting food amongst many other benefits.

Inulin can also provide benefits to a number of specific digestive issues such as constipation.^{(12, 17)}

Best inulin sources

Whilst inulin can be found in over 3000 vegetables, the primary sources of it come from foods such as garlic, asparagus roots, Jerusalem artichoke and chicory root, which all possess a 15-20% inulin content. It can also be found in a range of more commonly consumed foods such as bananas, onions, leeks, and barley although many of these only possess a 1-5% inulin content.

However, given that the average fibre intake within the UK is 10-15g lower than recommended values, many will find it difficult to obtain enough soluble fibre within their diet.⁽⁷⁾ As such, it may be beneficial to consume inulin in the form of a supplement.

Inulin dosage

When starting to take inulin, it’s commonly advised to start slow, perhaps by adding foods that are rich in it into your regular diet to begin with. If you decide to begin to supplement inulin, then begin with small doses between 2-3g per day for the first two weeks, followed by small increases of 1-2g per week up until a dose of around 10g per day. Although some studies have used intakes of between 20-30g per day, intakes within these ranges are more likely to result in greater side effects.^{(5, 14)}

Side effects of inulin

Whilst all individuals will respond differently to increases in inulin intake, those who consume a low FODMAP diet (restricting the amount of certain ‘short-chain’ carbohydrates) will generally experience significant side effects and are advised to avoid it.

Side effects range from slight discomfort to increases in gas and bloating when taken within the range with 7-10g per day.⁽¹⁵⁾

How to take inulin powder

Inulin powder can be added to any of your meals or drinks and can also be used to bake with. It’s commonly added worldwide to a number of food products as it doesn’t affect the taste or appearance of our food. For those who experience issues tolerating it, it’s advised to consume with meals in smaller divided doses across the day in order to improve tolerance.⁽¹¹⁾

Take home message

Inulin provides several important health benefits including improvements in glucose control, weight management and digestive health. It's safe for most people although those following a low FODMAP diet should likely avoid its consumption. For everyone else, when starting supplementing with inulin, start out with small doses (2-3g per day) and gradually increase to reduce potential side effects.