What are the different types of fibre in food?

December 25, 2025 •

3 min read

According to the Mayo Clinic, most Americans consume only about 15 grams of fibre per day, far below the recommended 25 to 38 grams. Understanding what are the different types of fibre in food is key to increasing your intake and reaping their unique health benefits. Fibre, the indigestible part of plant foods, is crucial for digestive health, blood sugar control, and even disease prevention.

Quick Summary

This article explores the major classifications of dietary fibre, primarily focusing on soluble and insoluble types. It details their distinct functions within the body, providing a comprehensive list of food sources and health benefits. The guide offers actionable advice for incorporating more fibre into your daily diet effectively.

Key Points

Soluble vs. Insoluble: Fibre is primarily classified into two types, soluble and insoluble, based on whether or not it dissolves in water.
Soluble Fibre Forms Gels: Soluble fibre creates a gel-like substance in your digestive tract, helping to slow digestion and absorb water.
Insoluble Fibre Adds Bulk: Insoluble fibre does not dissolve in water and acts as a bulking agent to promote regular bowel movements.
Diverse Food Sources: Both soluble and insoluble fibres are found in a wide range of plant foods, including whole grains, fruits, vegetables, and legumes.
Supports Gut Health: Some soluble fibres are fermented by gut bacteria, producing beneficial compounds that support a healthy gut microbiome.
Boosts Overall Health: An adequate intake of both fibre types helps manage cholesterol, regulate blood sugar, and lower the risk of chronic diseases.
Varies by Plant Part: The type and amount of fibre can differ depending on which part of the plant you consume, such as the skin versus the flesh of a fruit.
Increase Intake Gradually: To avoid digestive discomfort, it is recommended to increase fibre intake slowly and ensure you drink enough water.

Soluble Fibre: The Water-Dissolving Gel

Soluble fibre dissolves in water to form a gel in the digestive tract, slowing digestion. This can help lower blood cholesterol by binding to cholesterol particles. It also slows sugar absorption, aiding blood glucose regulation, which is beneficial for managing type 2 diabetes. Soluble fibre is fermented by gut bacteria in the large intestine, acting as a prebiotic that supports a healthy gut microbiome and produces beneficial short-chain fatty acids.

Common sources of soluble fibre include:

Legumes (lentils, peas)
Oats and barley (beta-glucans)
Fruits (apples, berries, bananas)
Root vegetables (carrots, sweet potatoes)
Nuts and seeds (chia, flaxseeds)

Insoluble Fibre: The Bulking Agent

Insoluble fibre does not dissolve in water and passes through the digestive system mostly intact, adding bulk to stool. This helps speed up the passage of food and waste, preventing constipation and promoting regular bowel movements. It supports bowel health and may lower the risk of diverticular disease and hemorrhoids. While not lowering cholesterol like soluble fibre, its bulking action is vital for digestive health. Most plant foods have both types, but some are richer in insoluble fibre.

Common sources of insoluble fibre include:

Whole grains (wheat bran, brown rice)
Nuts and seeds (almonds, walnuts)
Vegetables (green beans, cauliflower, potatoes with skin)
Fruits with edible skins (apples, pears)

The Rise of Prebiotic and Functional Fibres

Beyond soluble and insoluble, categories can include prebiotic and functional fibres. Prebiotic fibres are fermentable soluble fibres that nourish beneficial gut bacteria, supporting a healthy gut microbiome linked to overall well-being. Functional fibres are isolated, extracted, or manufactured non-digestible carbohydrates with proven health benefits, often added to foods or supplements (e.g., psyllium husk, inulin). Obtaining fibre from whole foods is generally preferred for a wider range of nutrients.

Comparing the Types of Fibre

Here is a comparison of soluble and insoluble fibre:


Feature	Soluble Fibre	Insoluble Fibre
Dissolves in Water?	Yes	No
Forms a Gel?	Yes	No
Digestion Speed	Slows it down	Speeds it up
Key Function	Lowers cholesterol and blood sugar	Adds bulk to stool; prevents constipation
Fermentable?	Highly fermentable	Less fermentable
Source Foods	Oats, beans, apples, carrots	Whole grains, wheat bran, nuts, seeds
Associated Benefit	Blood sugar control, heart health	Bowel regularity, prevention of constipation

Conclusion: Incorporating a Variety of Fibre

Both soluble and insoluble fibre are essential for health. The best approach is to eat a variety of plant foods to get a mix of both types. Include whole grains, fruits, vegetables, legumes, nuts, and seeds. Increase fibre gradually and drink plenty of water. A fibre-rich diet supports long-term well-being. For more, see the Harvard T.H. Chan School of Public Health: https://nutritionsource.hsph.harvard.edu/carbohydrates/fiber/.

Frequently Asked Questions (FAQs)

Q1: Is one type of fibre more important than the other? A1: Both soluble and insoluble fibres are crucial, each with different roles. Soluble fibre helps with blood sugar and cholesterol, while insoluble fibre aids bowel regularity. Consume a mix from various plant foods.

Q2: Can eating too much fibre cause problems? A2: A sudden large increase can cause gas and bloating. Increase intake gradually and drink plenty of water to help your digestive system adjust.

Q3: What role do supplements play in fibre intake? A3: Supplements can help but shouldn't replace fibre from whole foods. Whole foods offer more nutrients like vitamins and minerals.

Q4: Do fruits and vegetables lose their fibre content when juiced? A4: Juicing removes most insoluble fibre found in pulp and skin. Eating whole fruits and vegetables is generally more beneficial.

Q5: How does fibre help with weight management? A5: Fibre-rich foods are filling, helping control appetite. Soluble fibre slows digestion and promotes fullness.

Q6: What is a prebiotic fibre? A6: Prebiotic fibre is fermentable fibre that feeds beneficial gut bacteria. This supports a healthy gut microbiome, linked to better digestion and reduced inflammation.

Q7: Is fibre only found in whole grains? A7: No, fibre is in all plant foods: whole grains, fruits, vegetables, legumes, nuts, and seeds. Legumes are high in both soluble and insoluble fibre.

Q8: Can fibre from supplements interfere with medication? A8: Some supplements can interfere with medication absorption. Take supplements at a different time than medication and consult a healthcare provider.

Frequently Asked Questions

Soluble fibre dissolves in water to form a gel-like substance, which helps lower blood cholesterol and sugar levels. In contrast, insoluble fibre does not dissolve in water and adds bulk to stool, promoting regular bowel movements and preventing constipation.

Excellent sources of soluble fibre include oats, barley, nuts, seeds, beans, lentils, peas, and many fruits and vegetables like apples, carrots, and citrus fruits.

Foods rich in insoluble fibre include whole-wheat flour, wheat bran, brown rice, whole-grain cereals, and many vegetables such as green beans, cauliflower, and potatoes with the skin on.

Yes, soluble fibre is particularly effective at controlling blood sugar levels. By slowing the absorption of sugar, it helps prevent rapid blood glucose spikes after eating, which is especially important for people with diabetes.

Drinking plenty of water is essential when increasing your fibre intake. Fibre absorbs water, and without enough fluid, it can cause constipation, bloating, and other abdominal discomforts. Proper hydration is necessary for fibre to move through your system effectively.

While fibre supplements can help meet your daily needs, they are not a substitute for dietary fibre from whole foods. Whole plant foods offer a complete package of nutrients, including vitamins, minerals, and various phytonutrients, that supplements lack.

Certain types of soluble, fermentable fibre act as prebiotics, which are food for the beneficial bacteria in your gut. This fermentation process produces short-chain fatty acids that nourish the gut lining and reduce inflammation.