AACC challenges fiber definitions

The American Association of Cereal Chemists (AACC) is challenging the definitions for dietary, functional, and total fiber published by the Food Nutrition Board (FNB) of the Institute of Medicine and the National Academies last year.

The definitions proposed by FNB separate fiber into two categories (dietary fiber and functional fiber), which according to AACC, are arbitrary and could both confuse the consumer and present problems for food manufacturers trying to raise fibre levels in finished products.

In its September 2002 Dietary Reference Intakes report, the FNB defines dietary fiber as consisting of non-digestible carbohydrates and lignin that are intrinsic and intact in plants. Foods with dietary fiber include cereal bran, flaked corn cereal, sweet potatoes and onions. Functional fiber refers to those fiber sources that are shown to have similar health benefits as dietary fiber, but are isolated or extracted from natural sources or are synthetic, such as pectin extracted from citrus peel and used as a gel for jams and jellies. 'The definition of functional fiber aims to exclude fiber-like products, whether extracted or synthesized, that cannot be shown to have proven health benefits,' said FNB at the time.

However Jon DeVries, a member of the AACC Dietary Fiber TechnicalCommittee, says the FNB definitions not only present analytical andscientific concerns, but they are also confusing to the consumer andcould have a negative impact on nutritional research and education.

"A definition for dietary fiber must be scientifically sound, promoteinternational harmonization, and define the constitution and makeup ofmacrocomponent food based on its physiological or physical-chemicalproperties, not its state of being. The FNB definitions do not satisfythese requirements, do not reflect current scientific consensus on thephysiology of the dietary fiber, and are operationally impractical,"​DeVries said.

AACC, an organisation of around 3,500 grain scientists, also said that if dietary fiber is divided into two 'arbitrary categories', a 'severe limitation will be placed on food manufacturers trying to produce foods with the elevated fiber content necessary to meet daily recommended intakes'.

Based on the views of a global scientific review committee, the organisation has produced an alternative definition: 'Dietary fiber is the edible parts of plants or analogous carbohydrates that are resistant to digestion and absorption in the human small intestine with complete or partial fermentation in the large intestine; dietary fiber includes polysaccharides, oligosaccharides, lignin, and associated plant substances; dietary fibers promote beneficialphysiological effects including laxation, and/or blood cholesterolattenuation, and/or blood glucose attenuation.'

AACC said that this definition should form the basis of regulatory policy around the world, challenging the recommended fibre intakes from the FNB, the first issued on fibre, which were aimed at regulatory bodies in both the United States and Canada. FNB however claimed the categories were a way of clarifying the usefulness of content claims on the growing numbers of foods marketed as containing fiber.

For more information from the AACC, see the full report​.