Is Fibre Part of the Classes of Food?

December 18, 2025 •

3 min read

According to the Centre for Health Protection, dietary fibre is one of the seven major groups of nutrients, alongside carbohydrates, proteins, fats, vitamins, minerals, and water. This classification solidifies its status and emphasizes that fibre is part of the classes of food, serving distinct and essential functions for human health.

Quick Summary

Fibre is an essential nutrient and is categorized as a carbohydrate, though it remains largely undigested by the body. It is found in plants and is crucial for digestive health, blood sugar regulation, and cholesterol management. Dietary fibre is vital for overall health and is often classified into soluble and insoluble types.

Key Points

Fibre is a Nutrient Class: Dietary fibre is officially recognized as a major nutrient group, along with carbohydrates, proteins, fats, vitamins, minerals, and water.
Not Digested Like Other Carbs: Though a carbohydrate, fibre is not broken down into sugar for energy, instead passing largely intact through the digestive system.
Two Main Types: Fibre is split into soluble and insoluble types, with soluble fibre dissolving in water and insoluble fibre adding bulk to stool.
Multiple Health Benefits: Adequate fibre intake supports digestive regularity, helps regulate blood sugar, lowers bad cholesterol, and is associated with a reduced risk of heart disease, diabetes, and certain cancers.
Weight Management Aid: Fibre-rich foods promote a feeling of fullness, which can assist in weight management by reducing overall calorie consumption.
Best Sourced from Whole Foods: The best way to increase fibre intake is by eating a variety of whole plant foods, including fruits, vegetables, whole grains, and legumes, rather than relying on supplements.
Crucial for Gut Microbiome: Fermentable fibre feeds beneficial gut bacteria, contributing to a healthier gut and producing beneficial compounds like short-chain fatty acids.

Understanding the Classes of Food

Nutrients are the compounds in foods essential for life and health. They are traditionally classified into several major groups. The most common classification includes macronutrients, which are needed in larger quantities, and micronutrients, which are required in smaller amounts.

The Major Nutrient Classes

Historically, many sources refer to six primary nutrient classes: carbohydrates, proteins, fats, vitamins, minerals, and water. However, modern nutrition science, and some health organizations, also explicitly include dietary fibre as its own distinct category, bringing the total to seven essential nutrient groups. This distinction is made because, despite being a carbohydrate, fibre functions very differently within the human body compared to starches and sugars.

Why Fibre is Classified Separately

Fibre is a type of carbohydrate, but unlike other carbs that are broken down into glucose and absorbed by the body, fibre remains largely undigested. It passes through the stomach and small intestine relatively intact, continuing to the large intestine where it is partially or fully fermented by gut bacteria, depending on its type. This unique physiological path is what warrants its separate classification and recognition as a vital component of a healthy diet, rather than simply being lumped in with other carbohydrates.

Soluble vs. Insoluble Fibre

To fully appreciate fibre's role, it's helpful to understand its two main types. Most plant-based foods contain a mix of both soluble and insoluble fibre, each offering unique health benefits.

Soluble Fibre: This type of fibre dissolves in water and forms a gel-like substance in the digestive tract. It helps lower blood cholesterol and stabilize blood glucose levels, also contributing to a feeling of fullness. Sources include oats, beans, apples, and carrots.

Insoluble Fibre: This type of fibre does not dissolve in water. It adds bulk to stool and promotes digestive regularity, helping to prevent constipation. Sources include whole grains, nuts, seeds, and fruit and vegetable skins.

Health Benefits Beyond Digestion

A high-fibre diet is linked to a reduced risk of several chronic diseases.

Impact on Gut Health

Certain fibres act as prebiotics, feeding beneficial gut bacteria. This fermentation produces short-chain fatty acids beneficial for gut health and potentially anti-inflammatory.

Chronic Disease Prevention

Fibre-rich diets can lower the risk of cardiovascular disease, type 2 diabetes, and some cancers by binding to cholesterol and slowing sugar absorption.

Weight Management

Fibre adds bulk with fewer calories and soluble fibre can prolong fullness, aiding appetite control.

Fibre vs. Other Nutrient Classes


Feature	Dietary Fibre	Other Carbohydrates (Starches & Sugars)	Protein	Fats (Lipids)
Digestion	Mostly indigestible.	Broken down for energy.	Broken down for tissue repair.	Broken down for energy and storage.
Primary Function	Digestive health, gut support, cholesterol/blood sugar.	Primary energy source.	Building and repairing tissues.	Energy storage, organ protection.
Source	Plants only.	Plants and processed foods.	Animal and plant sources.	Animal and plant sources.
Caloric Value	Minimal calories.	4 calories/gram.	4 calories/gram.	9 calories/gram.

How to Increase Your Fibre Intake

Most adults don't meet the recommended 25g (women) or 38g (men) daily intake. Increase gradually and drink water.

Choose Whole Grains: Opt for whole-grain versions of bread, pasta, and rice.
Healthy Snacks: Eat whole fruits, nuts, seeds, and raw vegetables.
Add Legumes: Include beans, lentils, and peas in meals.
Eat Fruits and Vegetables: Consume plenty daily, including skins.

Conclusion

Is fibre part of the classes of food? Yes. While a carbohydrate, its unique function and benefits solidify its place as an essential nutrient class. Fibre is vital for digestion, blood sugar/cholesterol, and reducing chronic disease risk. Prioritizing diverse fibre-rich plant foods over supplements is key to better health.

Frequently Asked Questions

Fibre is a type of carbohydrate. However, unlike starches and sugars that are digested and used for energy, fibre is largely indigestible and serves unique functions in the body.

The two main types are soluble and insoluble fibre. Soluble fibre dissolves in water and helps lower cholesterol, while insoluble fibre adds bulk to stool to aid digestion.

The primary function of fibre is to maintain a healthy digestive system, prevent constipation, and support the beneficial bacteria in the gut microbiome.

Yes, fibre can help with weight management. Fibre-rich foods often have a lower calorie density and help you feel fuller for longer, which can reduce overall food intake.

For adults, the recommended daily intake is approximately 25 grams for women and 38 grams for men. However, most people consume much less than this recommended amount.

Good sources include whole grains (oats, brown rice), fruits (apples, berries), vegetables (broccoli, carrots), legumes (beans, lentils), nuts, and seeds.

While fibre supplements are available, it is generally recommended to get fibre from whole foods. Whole foods provide a mix of soluble and insoluble fibre, along with other essential vitamins and minerals that supplements often lack.