What Is Inulin and How Does It Work?

Did you know that an unassuming fibre called inulin is found in some of your favourite foods like ice cream, bread, and cereals? In your body, it primarily serves as food for the microorganisms in your gut. But inulin is more than just a simple fibre. Here, we show you which foods contain inulin, how it works in the body, how much you should eat — and how it is even used in industry.

What Is Inulin?

Inulin, not to be confused with insulin, is a natural fibre found in many plants functioning as an energy reserve. It consists of a chain of fructose molecules attached to a single glucose molecule. Inulin is commonly used in the food industry as a stabiliser, texturiser, or fat replacer. Since the human body cannot digest inulin in the small intestine like other nutrients, it reaches the colon intact, where it is processed by the resident microorganisms (gut bacteria).

How Does Inulin Work in the Body?

Inulin is not digested in the upper gastrointestinal tract (stomach and small intestine) because our body lacks the necessary enzymes to break the bonds between fructose molecules in inulin.

When inulin reaches the colon, it is fermented by bacteria, especially bifidobacteria and lactobacilli, into short-chain fatty acids (SCFAs) such as butyrate, acetate, and propionate. These bacteria use inulin as food, breaking it down in the process.

SCFAs provide energy for intestinal cells, maintain the acid-base balance in the gut, and create an acidic environment that inhibits the growth of pathogenic bacteria. They also promote mineral absorption from the intestine.

Which Foods Contain Inulin?

Foods containing inulin:

- Chicory root – one of the richest sources of inulin
- Jerusalem artichoke (sunchoke) – a tuber with very high inulin content
- Garlic
- Onion
- Leek
- Asparagus
- Bananas – contain small amounts of inulin, especially when slightly green
- Wheat – particularly whole wheat is a good source of inulin
- Rye – similar to wheat, rye contains inulin
- Agave
- Yacon – a tuber closely related to sunchoke

Here are some examples of unulin-rich foods and their quantities.

How Much Inulin Is Healthy?

There is no general rule for how much inulin to consume daily. Inulin can be part of a healthy fibre intake. The German Nutrition Society recommends a daily fibre intake of 30 grams or more. Inulin can contribute to this amount. Depending on diet, people typically consume between 3 and 11 grams of inulin and other long-chain carbohydrates daily. Most people tolerate up to 30 grams of inulin spread throughout the day. Sensitive individuals may experience bloating or diarrhoea with less than 10 grams daily.

What You Should Consider:

As an inulin newbie, start with a small amount, such as 1 to 2 grams daily. This allows your digestive system to adjust, reducing the risk of side effects like bloating or diarrhoea. Consider your overall inulin intake, as it naturally occurs in many foods (see list above). Those with certain digestive disorders like irritable bowel syndrome or sensitive gut conditions should use inulin only under medical supervision.

In Which Industries Is Inulin Used?

Inulin is used in various sectors of the food industry due to its properties as both a fibre and a functional food additive. Check your pantry to see if you can spot inulin on ingredient lists.

Food Industry

• Texture Enhancer and Fat Substitute: Used in dairy products like milk ice cream, baked goods, and spreads to improve creaminess and mouthfeel without increasing fat content.
• Calorie Reduction: Inulin has a lower calorie density than many carbohydrates, making it ideal for reduced-calorie or light foods.
• Addition to Certain Foods: Added to yoghurts, beverages, and other foods to feed beneficial gut bacteria, such as in certain oat milk products.
• Improving Baking Properties: Used in baked goods to retain moisture and improve texture.

The History of Inulin

Inulin was discovered in 1804 by Valentin Rose, who described it as a white substance derived from the roots of the plant Inula helenium, part of the sunflower family. Confusion in the literature arose due to various substances mistaken for inulin. It was not until Karl Prantl's 1870 publication "Das Inulin: Ein Beitrag zur Pflanzenphysiologie" that inulin was clearly defined, describing its structure and chemical properties. Prantl left readers with two intriguing questions: "But why is inulin only deposited in the underground organs, and why is it formed only in a few plant families? These are questions we must leave to the future."