Table 1: Categorization of recent definitions of fiber based on whether or not a distinction in dietary fiber source is made.

Plant source only

Food and Agriculture Organization (FAO)/World Health Organization (WHO):
“Dietary fibre consists of intrinsic plant cell wall polysaccharides” [40]

Categorize fiber types based on source

Institute of Medicine (IOM):
“Dietary fiber consists of nondigestible carbohydrates and lignin that are intrinsic and intact in plants
Functional fiber consists of isolated, nondigestible carbohydrates that have beneficial physiological effects in humans
Total fibre is the sum of dietary fibre and functional fiber” [368]
Health Canada1:
“Dietary fibre consists of the endogenous components of plant material in the diet which are resistant to digestion by enzymes produced by
humans. They are predominantly nonstarch polysaccharides and lignin and may include, in addition, associated substances” [369]
“Novel Fibre or Novel Fibre Source means a food that is manufactured to be a source of dietary fibre, and
 (i) that has not traditionally been used for human consumption to any significant extent, or
 (ii) that has been chemically processed, for example, oxidized, or physically processed, for example, very finely ground, so as to modify
 the properties of the fibre contained therein, or
 (iii) that has been highly concentrated from its plant source” [370]
Codex Alimentarius Commission2:
“Dietary fibre means carbohydrate polymers with ten or more monomeric units, which are not hydrolysed by the endogenous enzymes in
the small intestine of humans and belong to the following categories:
 (i) edible carbohydrate polymers naturally occurring in the food as consumed,
 (ii) carbohydrate polymers which have been obtained from food raw material by physical, enzymatic, or chemical means and which
  have been shown to have a physiological effect of benefit to health as demonstrated by generally accepted scientific evidence to
  competent authorities,
Synthetic carbohydrates polymers which have been shown to have a physiological effect of benefit to health as
demonstrated by generally accepted scientific evidence to competent authorities” [30]

No categorization of fibers based on source

European Food Safety Authority (EFSA):
“Nondigestible carbohydrates plus lignin” [371]
Food Standards Australia New Zealand (FSANZ), formerly Australia New Zealand Food Authority (ANZFA)
“Dietary fibre means the fraction of the edible part of plants or their extracts, or synthetic analogues that
 (a) are resistant to the digestion and absorption in the small intestine, usually with complete or partial fermentation in the large
 (b) promote one or more of the following beneficial physiological effects:
  (i) laxation,
  (ii) reduction in blood cholesterol,
  (iii) modulation of blood glucose,
and includes polysaccharides, oligosaccharides (DP < 2), and lignin” [372]

1Health Canada is currently reviewing its definition for fiber and proposed a new definition in December 2010 which has not yet been accepted [373].
2Two footnotes have been included with this definition, the first indicates that substances associated with fibre (e.g., lignin, waxes, saponins, etc.) are included in this definition, unless they are isolated and reintroduced into a food. The second footnote states that the decision on whether to include carbohydrates from 3 to 9 monomeric units is up to the discretion of national authorities.