Dietary fibres for nutrition formulations

Dietary fibres are carbohydrate polymers which are neither digested nor absorbed in the small intestine. They can be divided into two main types, the soluble dietary fibres and the insoluble dietary fibres.

Soluble fibres dissolve in water and form a gel-like substance in the gut. They come from different sources such as:

• Pectin from apples, carrots, citrus, orange, and pea.
• Beta-glucans from barley
  Inulin, oligofructose from chicory and agave
• Micronized cellulose from mechanical processed cellulose
• Arabinoxylan from psyllium

Soluble fibres are a heterogeneous group with varying chemical compositions and physicochemical properties, such as degree of polymerization. These properties influence microbial fermentation in the intestines and determine whether the fibres can be classified as prebiotic. Fibres such as beta-glucans and pectin process have high solubility and add viscosity – they are highly fermentable. The inulin-type fructans – inulin and oligofructose – are non-viscous, soluble fibres that are also highly fermentable. Micronized cellulose, with its small particle size, can be more readily fermented by microorganisms. Psyllium fibres are soluble and highly viscous. They are slowly and only partially fermented, which may provide prolonged support to the microbiome over time.

Insoluble fibres do not dissolve in water and are generally poorly fermented in the gut. They add bulk to stools and stimulate bowel movements. The insoluble fibres include cellulose, hemicellulose, and lignin and come from sources like bamboo, buckwheat, cocoa, maize, and wheat bran. Some sources like apples, pea, and carrots have a good balance of both soluble and insoluble fibres containing both soluble pectin fibres, and insoluble cellulose, hemicellulose and lignin fibres.