[PPT] - Dietary Fiber Definitions: From a Historical Perspective to the Way PowerPoint Presentation

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Jan Delcour KU Leuven 22e Voedings- en Gezondheidscongres, Brussel, November 15 2019

Dietary Fiber Definitions: From a Historical Perspective to the Way Forward

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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 Research Centre (LFoRCe) 2

Outline

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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 Research Centre (LFoRCe) 3

Outline

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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 Research Centre (LFoRCe) 4

The concept of dietary fiber: yesterday

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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 Research Centre (LFoRCe) 5

The concept of dietary fiber: yesterday

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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 Research Centre (LFoRCe) 6

The concept of dietary fiber: yesterday

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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 Research Centre (LFoRCe) 7

The concept of dietary fiber: yesterday

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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

r partial fermentation in the large intestine. DF includes polysaccharides,
ligosaccharides, 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 Research Centre (LFoRCe) 8

The concept of dietary fiber: yesterday

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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 Research Centre (LFoRCe) 9

The concept of dietary fiber: yesterday

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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.

Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 10

The concept of dietary fiber: yesterday

Continued…

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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 Research Centre (LFoRCe) 11

The concept of dietary fiber: yesterday

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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 Research Centre (LFoRCe) 12

The concept of dietary fiber: yesterday

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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 Research Centre (LFoRCe) 13

Outline

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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 Research Centre (LFoRCe) 14

The concept of dietary fiber: today

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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 Research Centre (LFoRCe) 15

The concept of dietary fiber: today

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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 Research Centre (LFoRCe) 16

The concept of dietary fiber: today

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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 Research Centre (LFoRCe) 17

Wheat dietary fiber

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Laboratory of Food Chemistry and Biochemistry Leuven Food Science and Nutrition Research Center

Aleurone layer

(6-9%)

Starchy endosperm (80-85%)

Starch
Proteins
Lipids
Antioxidants
Vitamin E
B vitamins
Minerals
Soluble &

insoluble dietary fiber

Proteins
Antioxidants

(phenolic acids)

Vitamin E
B vitamins
Choline,

betaine

Minerals
Phytic acid

Germ (3%)

Insoluble dietary

fiber ARABINOXYLAN

Antioxidants

(phenolic acids)

Inner and

uter

pericarp (4-5%)

Bran

Courtesy of Healthgrain Forum

Wheat dietary fiber

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5

O O O O H OH

5 4 3 2 1

A

O OH OH O H O O O O H O

5 4 3 2 1 1 2 3 4

B D

5 4 3 2 1 5 1 2 3 4 5

O OH OH O H O O OH OH O H O O O O

1 2 3 4 5 4 3 2 1 5

O OH OH O OH O O O O O OH H3CO

1 2 3 4

C

Wheat dietary fiber

Arabinoxylan

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Seed coat: 40% AX Pericarp: 40% AX Aleurone: 30% AX Starchy endosperm 2% AX Technical bran 35% AX

Red: protein, blue: cell walls, yellow: lignified cell walls Courtesy of Karin Autio, VTT

Wheat dietary fiber

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Laboratory of Food Chemistry and Biochemistry Leuven Food Science and Nutrition Research Center

Wheat dietary fiber …. and minerals

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European Commission Directive (October 28 2008): edible carbohydrate polymers naturally occurring in foods

Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 22

Wheat dietary fiber

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European Commission Directive (October 28 2008): 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,

Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 23

Isolated dietary fiber

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European Commission Directive (October 28 2008): Whereas … “Fibre has been traditionally consumed as plant material and has one or more beneficial physiological effects such as decrease intestinal transit time, increase stool bulk, is fermentable by colonic microflora, reduce blood total cholesterol, reduce blood LDL cholesterol levels, reduce post-prandial blood glucose, or reduce blood insulin levels. Recent scientific evidence has shown that similar beneficial physiological effects may be obtained from other carbohydrate polymers that are not digestible and not naturally occurring in the food as consumed…”

Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 24

The concept of dietary fiber: today

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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 Research Centre (LFoRCe) 25

Outline

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CLAIMS: Wheat bran and wheat bran enriched foods (EFSA):

Regular consumption of wheat bran significantly reduces intestinal transit time
Wheat bran promotes intestinal health by significantly decreasing intestinal

transit time

Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 26

Dietary fibers with established health effects

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CLAIMS: Wheat bran and wheat bran enriched foods (EFSA):

Regular consumption of wheat bran significantly reduces intestinal transit time
Wheat bran promotes intestinal health by significantly decreasing intestinal

transit time

Regular wheat bran consumption significantly increases faecal bulk
Wheat bran promotes intestinal health by significantly increasing faecal bulk

Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 27

Dietary fibers with established health effects

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CLAIMS: Oat and barley beta-glucan (EFSA):

Oat beta-glucans have been shown

to lower/reduce blood cholesterol.

High cholesterol is a risk factor in the

development of coronary heart disease.

Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 28

Dietary fibers with established health effects

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CLAIM: Wheat endosperm arabinoxylan (EFSA):

Consumption of arabinoxylan contributes

to a reduction of the glucose rise after a meal.

Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 29

Dietary fibers with established health effects

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CLAIM: Chicory inulin (EFSA):

Chicory inulin contributes to maintenance of normal defecation by increasing

stool frequenc

Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 30

Dietary fibers with established health effects

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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 Research Centre (LFoRCe) 31

Outline

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Prebiotics are “non-digestible food ingredients that selectively stimulate the

growth and/or activity of one or a limited number of bacteria in the colon which improve host health” (Journal of Nutrition, 1995, 125, 1401)

“A prebiotic is a selectively fermented ingredient that allows specific changes

both in the composition and/or activity of the gastrointestinal microflora that confer benefits upon host wellbeing and health” (Nutrition Research Reviews, 2004, 17, 259)

Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 32

Are prebiotics prebiotics ?

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Prebiotics: criteria (Nutrition Research Reviews, 2004, 17, 259):

Resistance to acidity
Resistance to hydrolysis by mammalian enzymes
Resistance to gastrointestinal absorption
Fermentation by intestinal microflora
Selective stimulation of growth and/or activity of intestinal bacteria associated

with health and wellbeing

Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 33

Are prebiotics prebiotics ?

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Prebiotics and dietary fibers: shared criteria

Resistance to gastric acidity: YES
Resistance to hydrolysis by mammalian enzymes: YES
Resistance to gastrointestinal absorption: YES
Fermentation by intestinal microflora: YES
Selective stimulation of growth and/or activity of intestinal bacteria associated

with health and wellbeing: NO

Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 34

Are prebiotics prebiotics ?

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Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 35

Are prebiotics prebiotics ?

Stimulating beneficial bacteria

(e.g.Bifidobacterium)

Suppressing pathogenic bacteria

(e.g.Salmonella)

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Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 36

Are prebiotics prebiotics ?

carbohydrates positive effects butyrate propionate acetate proteins NH3 phenols thiols isobutyrate isovalerate negative effects NH3 phenols thiols proteins carbohydrates

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Prebiotics

Inulin and fructo-oligosaccharides (GFn, FOS)
Xylo-oligosaccharides (XOS)
Arabinoxylan oligosaccharides (AXOS)
Galacto-oligosaccharides (GOS)
Synthetic fibres

Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 37

Are prebiotics prebiotics ?

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Prebiotics (EFSA): Claimed effects:

“beneficial effect on intestinal microflora”,
“gut integrity, digestion”,
“intestinal bifidobacteria”,
“prebiotic effect”,
“prebiotic”,
“intestinal health”.

Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 38

Are prebiotics prebiotics ?

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Prebiotics (EFSA): The Panel

considers that the evidence … does not establish that increasing numbers of

gastro-intestinal microorganisms is a beneficial physiological effect.

concludes that a cause and effect relationship has not been established

between the consumption of the foods/food constituents which are the subject

f the health claims and a beneficial physiological effect related to increasing

numbers of gastro-intestinal microorganisms.

Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 39

Are prebiotics prebiotics ?

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Inulin type fructans (EFSA): The Panel

considers that … inulin-type fructans, which are the subject of the health

claims, are not sufficiently characterised in relation to the claimed effects …

concludes that a cause and effect relationship cannot be established between

the consumption of inulin-type fructans and the claimed effects …

Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 40

Are prebiotics prebiotics ?

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More work is needed to link the impact of prebiotics on the composition and/or

activity in the gastrointestinal microbiota to benefits for host wellbeing and health.

A successful outcome of such work can lead to a prebiotics health claim.

Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 41

Are prebiotics prebiotics ?

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Q: Are prebiotics prebiotics ?

A: No, today, prebiotics are not prebiotics …

Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 42

Are prebiotics prebiotics ?

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Q: Are prebiotics prebiotics ?

A: No, today, prebiotics are not prebiotics …

Q: Can prebiotics become prebiotics ?

A: Yes, prebiotics can become prebiotics …

Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 43

Are prebiotics prebiotics ?

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Q: Are prebiotics prebiotics ?

A: No, today, prebiotics are not prebiotics …

Q: Can prebiotics become prebiotics ?

A: Yes, prebiotics can become prebiotics …

Q: Are prebiotics DF ?

A: Yes, prebiotics are DF…

Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 44

Are prebiotics prebiotics ?

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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 Research Centre (LFoRCe) 45

Outline

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Over time, DF definitions have increasingly taken into account beneficial

physiological effects.

Even today, there are different DF definitions.
Some DF has beneficial physiological effects that have been translated in

specific end points and therefore have resulted in a health claim.

Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 46

Conclusions

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More work is needed to link the impact of prebiotics on the composition and/or

activity in the gastrointestinal microbiota to benefits for host wellbeing and health.

A successful outcome of such work can lead to prebiotic health claim.
In a worst case scenario, one may consider to abandon the term prebiotics

as such term would offer little benefit over the use of the term DF.

Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe) 47

Conclusions

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