What is the Difference Between Dietary Fibre and Crude Fibre

The main difference between dietary fibre and crude fibre is that dietary fibre is the sum of soluble and non-soluble fiber from plant-based foods that contain pectins, gums, and mucilage, whereas crude fibre is the insoluble part of the cell wall of plants which mostly consists of cellulose, lignin, and pentosan.

Dietary fibre and crude fibre are two types of fibre that occur in the diet. Usually, dietary fibre is the indigestible part of the food, mainly derived from plant materials. Therefore, crude fiber is a type of dietary fiber. However, there are two types of dietary fibre; soluble and insoluble fibre.

Key Areas Covered

1. What is Dietary Fibre
   • Definition, Features, Importance
2. What is Crude Fibre
   • Definition, Features, Importance
3. Similarities Between Dietary Fibre and Crude Fibre
   • Outline of Common Features
4. Difference Between Dietary Fibre and Crude Fibre
   • Comparison of Key Differences

Key Terms

Crude Fibre, Dietary Fibre, Plant Materials

What is Dietary Fibre

Dietary fibre or roughage is the portion of plant-derived food that cannot be completely broken down by human digestive enzymes. Therefore, it contains indigestible complex carbohydrates. Dietary fibers perform important biological functions, though they supply no calories or nutrients and are resistant to digestive enzymes. Usually, dietary fibre contains pectins, gums, and mucilage. Generally, there are two types of dietary fibre: soluble fibre and insoluble fibre. Moreover, many food products list total fiber content in grams, which includes both soluble and insoluble fiber.

Figure 1: Wheat Bran is a Good Source of Insoluble Fibre 

Soluble Fiber

Water-soluble fibre absorbs water and becomes a gel during the digestive process. As a gel, it slows digestion. On the other hand, soluble fibre, such as pectin and lignin, helps to prevent cholesterol from building up in blood vessel walls and thus helps to prevent heart disease. It can also help to stabilize blood sugar levels, which is beneficial for individuals with diabetes. Good sources of soluble fibre include barley, oat bran, seeds, nuts, peas, beans, and lentils, as well as some vegetables and fruit. Normally, plant-based foods typically contain 25 percent to 30 percent soluble fibre, which usually is less than their insoluble fibre content.

Insoluble Fiber

Insoluble fibre passes through the stomach and intestines undigested. But it absorbs water and organic toxins and waste. Insoluble fibre also adds bulk to stool and encourages food to pass through the digestive tract more quickly. Good sources of insoluble fibre include whole grains, wheat bran, and vegetables such as celery, spinach, and fresh tomatoes.

What is Crude Fibre

Crude fiber refers to one type of dietary fiber, the type that remains as residue after food receives a standardized laboratory treatment with dilute acid and alkali. The treatment dissolves all the soluble fiber and some of the insoluble fiber in a food. More importantly, the residue or crude fiber is primarily composed of cellulose and lignin.

Figure 2: Crude Fibre

Normally, crude fiber measurements, the result of lab analysis, may underestimate the actual dietary fiber in a food item by 50 percent or more.

Similarities Between Dietary Fibre and Crude Fibre

• Dietary fibre and crude fibre are two types of fibre that occur in food.
• They are plant materials.
• They are indigestible.

Difference Between Dietary Fibre and Crude Fibre

Definition

Dietary fibre or roughage refers to the part of plant-derived food that cannot be completely broken down by human digestive enzymes while crude fibre refers to a measure of the quantity of indigestible cellulose, pentosans, lignin, and other components of this type present in food.

Components

Soluble and insoluble fibres are the two types of dietary fibre while crude fibre is the insoluble part of the plant cell walls.

Include

Dietary fibre includes pectins, gums, and mucilage while crude fibre contains cellulose, pentosan, and lignin.

Function

Dietary fibres are carbohydrates that increase the size of stool to decrease the chance of constipation while crude fibres are insoluble and stimulate digestion and also encourage the production of important intestinal bacteria. 

Sources

Dietary fibre occurs in whole grain products, fruits, vegetables, beans, peas, legumes, nuts, and seeds while crude fiber occurs in the walls of plants. 

Conclusion

In brief, dietary fibre and crude fibre are two types of fibres that occur in food. Both are plant cell wall materials and are indigestible. However, dietary fibre includes pectins, gums, and mucilage. But crude fibre includes cellulose, pentosan, and lignin. On the other hand, the two types of dietary fibre are soluble fobre and insoluble fibre. The main difference between dietary fibre and crude fibre is their origin.

References:

1. Wikimedia Foundation. (2022, August 13). Dietary fiber. Wikipedia. Retrieved August 23, 2022.
2. Crude fiber. Food Science. (n.d.). Retrieved August 23, 2022.

Image Courtesy:

1. “WheatBran” By Alistair1978 – Own Work (CC BY-SA 2.5) via Commons Wikimedia
2. “Fruit, Vegetables and Grain NCI Visuals Online” By Unknown – Own Work (Public Domain) via Commons Wikimedia