What is Fiber ?

Fiber, or fibre in British English, is a term often used to refer to dietary fiber.  So what is dietary fiber? 

Dietary fiber is a broad category that is applied to a class of food materials with specific physical and chemical properties.  Unlike fats, carbohydrates, and proteins, dietary fiber is not digested by the enzymes in the stomach nor is it absorbed by the body.  Instead, dietary fiber pushes through the digestive system:  it may be fermented in the large intestine or be passed through the body intact.

What is fiber?



Graph: NUTRIOSE® digestion pattern

Dietary fiber, often referred to as roughage, is the indigestible part of plant foods, seeds, and grains.  It may also include components from plan and grain sources that are minimally processed.  Generally, there are two broad classifications of fibers based on their solubility in water:  soluble and insoluble fibers.

Insoluble fibers, as their name suggests, do not dissolve in water. In general, insoluble fibers are associated with roughage and bulk and have been shown to promote passage of foodstuffs through the digestive tract. Consumption of insoluble fibers has been shown to alleviate the symptoms of constipation and laxation or loose bowel movements.

Soluble fibers dissolve in water although with different dissolution times and extent, and can be further classified into high viscosity and low viscosity fibers. High viscosity soluble fibers often have gelling properties and many have been shown to lower blood cholesterol and blood glucose levels. 

Low viscosity soluble fibers dissolve quickly in water without significantly changing the liquid’s texture or viscosity.  In the digestive system, many soluble fibers ferment in the large intestine, and it is this fermentation which results in what are referred to as prebiotic effects, notably the stimulation of good bacteria (microflora) in the digestive system that are said to be beneficial to one’s digestive health.

Fiber digestion pattern

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Why eat fiber ?

Eating fiber has many health benefits and fiber is an essential part of a healthy diet. But beyond normal digestive function, fiber has been shown to contribute beneficially to health in other ways. Some fibers have been shown to lower blood cholesterol, to change the balance of microflora in the gut in beneficial ways, and to promote a feeling of satiety, or fullness after eating which can impact weight loss and management.

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