title: Re-evaluation of the mechanisms of dietary fibre and implications for macronutrient bioaccessibility, digestion and postprandial metabolism.
abstract: The positive effects of dietary fibre on health are now widely recognised; however, our understanding of the mechanisms involved in producing such benefits remains unclear. There are even uncertainties about how dietary fibre in plant foods should be defined and analysed. This review attempts to clarify the confusion regarding the mechanisms of action of dietary fibre and deals with current knowledge on the wide variety of dietary fibre materials, comprising mainly of NSP that are not digested by enzymes of the gastrointestinal (GI) tract. These non-digestible materials range from intact cell walls of plant tissues to individual polysaccharide solutions often used in mechanistic studies. We discuss how the structure and properties of fibre are affected during food processing and how this can impact on nutrient digestibility. Dietary fibre can have multiple effects on GI function, including GI transit time and increased digesta viscosity, thereby affecting flow and mixing behaviour. Moreover, cell wall encapsulation influences macronutrient digestibility through limited access to digestive enzymes and/or substrate and product release. Moreover, encapsulation of starch can limit the extent of gelatinisation during hydrothermal processing of plant foods. Emphasis is placed on the effects of diverse forms of fibre on rates and extents of starch and lipid digestion, and how it is important that a better understanding of such interactions with respect to the physiology and biochemistry of digestion is needed. In conclusion, we point to areas of further investigation that are expected to contribute to realisation of the full potential of dietary fibre on health and well-being of humans.
authors.affiliation: 1Biopolymers Group,Diabetes and Nutritional Sciences Division,King's College London,Franklin-Wilkins Building,150 Stamford Street,London SE1 9NH,UK.
authors.forename: Myriam M-L
authors.initials: MM
authors.lastname: Grundy
authors.affiliation: 1Biopolymers Group,Diabetes and Nutritional Sciences Division,King's College London,Franklin-Wilkins Building,150 Stamford Street,London SE1 9NH,UK.
authors.forename: Cathrina H
authors.initials: CH
authors.lastname: Edwards
authors.affiliation: 2Institute of Food Research,Norwich Research Park,Colney,Norwich NR4 7UA,UK.
authors.forename: Alan R
authors.initials: AR
authors.lastname: Mackie
authors.affiliation: 3ARC Centre of Excellence in Plant Cell Walls,Centre for Nutrition and Food Sciences,Queensland Alliance for Agriculture and Food Innovation,The University of Queensland,Brisbane 4072,Qsd,Australia.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Gidley
authors.affiliation: 1Biopolymers Group,Diabetes and Nutritional Sciences Division,King's College London,Franklin-Wilkins Building,150 Stamford Street,London SE1 9NH,UK.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Butterworth
authors.affiliation: 1Biopolymers Group,Diabetes and Nutritional Sciences Division,King's College London,Franklin-Wilkins Building,150 Stamford Street,London SE1 9NH,UK.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Ellis
mesh_terms: D001682:Biological Availability; D004043:Dietary Fiber / Q000378:metabolism*; D004063:Digestion / Q000502:physiology*; D005504:Food Analysis; D006801:Humans; D009753:Nutritive Value; D019518:Postprandial Period / Q000502:physiology*
keywords: Bioaccessibility; Dietary fibre; Food structure; GI gastrointestinal; Gastrointestinal functions; Plant cell walls