Dietary Fiber Definitions: From a Historical Perspective to the Way Forward Jan Delcour KU Leuven 22 e Voedings- en Gezondheidscongres, Brussel, November 15 2019
Outline • The concept of dietary fiber: yesterday • The concept of dietary fiber: today • Dietary fibers with established health effects • Are prebiotics prebiotics ? • Conclusions Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition 2 Research Centre (LFoRCe)
Outline • The concept of dietary fiber: yesterday • The concept of dietary fiber: today • Dietary fibers with established health effects • Are prebiotics prebiotics ? • Conclusions Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition 3 Research Centre (LFoRCe)
The concept of dietary fiber: yesterday Hipsley (1953): “dietary fiber” (DF): shorthand term for non -digestible constituents that make up plant cell walls. Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition 4 Research Centre (LFoRCe)
The concept of dietary fiber: yesterday Hipsley (1953): “dietary fiber” (DF): shorthand term for non -digestible constituents that make up plant cell walls. Trowell (1972): “DF is the proportion of food derived from cellular walls of plants which is digested very poorly in human beings”. Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition 5 Research Centre (LFoRCe)
The concept of dietary fiber: yesterday Hipsley (1953): “dietary fiber” (DF): shorthand term for non -digestible constituents that make up plant cell walls. Trowell (1972): “DF is the proportion of food derived from cellular walls of plants which is digested very poorly in human beings”. Trowell et al (1976): DF definition broadened to include indigestible polysaccharides such as gums, modified celluloses, mucilages, oligosaccharides , and pectins. Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition 6 Research Centre (LFoRCe)
The concept of dietary fiber: yesterday Trowell, Burkitt, Walker, and Painter (1972-1976): Used the term DF in conjunction with DF hypotheses postulating the inverse relationship between insufficient DF consumption, colon cancer and heart disease incidence. Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition 7 Research Centre (LFoRCe)
The concept of dietary fiber: yesterday Trowell, Burkitt, Walker, and Painter (1972-1976): Used the term DF in conjunction with DF hypotheses postulating the inverse relationship between DF consumption, colon cancer and heart disease incidence. American Association of Cereal Chemists (2001): “DF 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. DF includes polysaccharides, oligosaccharides, lignin, and associated plant substances. DFs promote beneficial physiological effects including laxation, and/or blood cholesterol attenuation, and/or blood glucose attenuation” . Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition 8 Research Centre (LFoRCe)
The concept of dietary fiber: yesterday Institute of Medicine (IOM, 2002): “DF consists of non -digestible carbohydrates and lignin that are intrinsic and intact in plants. Added fiber consists of isolated, non-digestible carbohydrates that have beneficial physiological effects in humans . Total fiber is the sum of DF and added fiber.” Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition 9 Research Centre (LFoRCe)
The concept of dietary fiber: yesterday Codex Alimentarius (2007): DF means carbohydrate polymers with a degree of polymerisation (DP) not lower than 3 , which are neither digested nor absorbed in the small intestine. A DP not lower than 3 is intended to exclude mono- and disaccharides.... DF consists of one or more of: • edible carbohydrate polymers naturally occurring in the food as consumed, • carbohydrate polymers, which have been obtained from food raw material by physical, enzymatic or chemical means, • synthetic carbohydrate polymers. Continued… Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition 10 Research Centre (LFoRCe)
The concept of dietary fiber: yesterday Codex Alimentarius (2007): DF generally has properties such as: • decreases intestinal transit time and increases stool bulk, • fermented by colonic microflora, • reduces blood total and/or LDL cholesterol levels, • reduces post-prandial blood glucose and/or insulin levels. Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition 11 Research Centre (LFoRCe)
The concept of dietary fiber: yesterday Codex Alimentarius (2007): DF generally has properties such as: • decreases intestinal transit time and increases stool bulk, • fermented by colonic microflora, • reduces blood total and/or LDL cholesterol levels, • reduces post-prandial blood glucose and/or insulin levels. With the exception of non-digestible edible carbohydrate polymers naturally occurring in foods as consumed … where a declaration or claim is made with respect to DF, a physiological effect should be scientifically demonstrated by clinical studies and other studies as appropriate. Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition 12 Research Centre (LFoRCe)
Outline • The concept of dietary fiber: yesterday • The concept of dietary fiber: today • Dietary fibers with established health effects • Are prebiotics prebiotics ? • Conclusions Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition 13 Research Centre (LFoRCe)
The concept of dietary fiber: today • Recommendations from the US IOM: … adults should consume 20– 35 grams of DF/day • Average intake of DF/day: … only 12– 18 grams of DF/day. Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition 14 Research Centre (LFoRCe)
The concept of dietary fiber: today European Commission Directive (October 28 2008): “ Fibre means carbohydrate polymers with 3 or more monomeric units , which are neither digested nor absorbed in the human small intestine and belong to following categories: • edible carbohydrate polymers naturally occurring in foods as consumed, • edible carbohydrate polymers, which have been obtained from food raw material food by physical, enzymatic, or chemical means and which have a beneficial physiological effect demonstrated by generally accepted scientific evidence, • edible synthetic carbohydrate polymers which have a beneficial physiological effect demonstrated by generally accepted scientific evidence .” Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition 15 Research Centre (LFoRCe)
The concept of dietary fiber: today European Commission Directive (October 28 2008): “ Fibre means carbohydrate polymers with 3 or more monomeric units , which are neither digested nor absorbed in the human small intestine and belong to following categories: • edible carbohydrate polymers naturally occurring in foods as consumed Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition 16 Research Centre (LFoRCe)
Wheat dietary fiber European Commission Directive (October 28 2008): edible carbohydrate polymers naturally occurring in foods as consumed Dietary Fiber content 8.3 g/100 g 3.3 g/100 g Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition 17 Research Centre (LFoRCe)
Wheat dietary fiber • Soluble & insoluble dietary fiber • Proteins Starchy endosperm • Antioxidants (80-85%) (phenolic acids) Aleurone layer • Starch • Vitamin E • Proteins (6-9%) Bran • B vitamins • Choline, betaine • Minerals • Phytic acid • Lipids Inner • Antioxidants • Insoluble dietary and • Vitamin E fiber ARABINOXYLAN outer • B vitamins • Antioxidants Germ pericarp • Minerals (phenolic acids) (3%) (4-5%) Courtesy of Healthgrain Forum Laboratory of Food Chemistry and Biochemistry Leuven Food Science and Nutrition Research Center
Wheat dietary fiber 4 O 4 O 5 5 2 O O 2 O O 1 1 H O 3 H O 3 OH O O 2 1 OH A B OH H O 4 3 5 4 O 4 O 5 5 O 2 O 2 O O 1 1 O 3 O 3 O O O OH 2 1 OH 2 O 1 OH OH H O O O OH 2 4 1 OH 3 Arabinoxylan 4 3 OH H O 5 5 4 3 C D 5 H 3 CO OH
Wheat dietary fiber Pericarp: 40% AX Technical bran 35% AX Seed coat: 40% AX Aleurone: 30% AX Starchy endosperm 2% AX Courtesy of Karin Autio, VTT Red: protein, blue: cell walls, yellow: lignified cell walls
Wheat dietary fiber …. and minerals Laboratory of Food Chemistry and Biochemistry Leuven Food Science and Nutrition Research Center
Wheat dietary fiber European Commission Directive (October 28 2008): edible carbohydrate polymers naturally occurring in foods Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition 22 Research Centre (LFoRCe)
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