Dietary fibre

1. {
Dietary Fibre
Chair person: Dr. Chandrashekar K
Student: Dr.Chetan Rangappa

2. Introduction
 The term Dietary Fibre was coined by Hipsley in 1953 to
denote Indigestible plant cell wall material
 In the olden days dietary fibre (DF) was known as 'roughage
or bulk'.
 Nowadays dietary fibre is also referred to as non-starch
polysaccharide (NSP).
 Fibres help us clean our digestive tracts ( i.e,“Our Body's
Broom").

3.  Plant cell walls are the major source of dietary fiber. The major
fibres of foods are cellulose, hemicelluloses, β- glucans and
pectins.
 Gums and lignin are minor fibres of foods.

4.  Definition:
“Dietary fibre 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 fibre includes
polysaccharides, oligosaccharides, lignin and associated
substances (Anon 2001, adopted by American Association of
Cereal Chemists, AACC).
 Dietary fibres promote beneficial physiological effects
including laxation, and blood cholesterol attenuation,
and blood glucose attenuation (AACC annual meeting)

5. The dietary fibre hypothesis
Dietary fibre hypothesis was based upon the pioneering
observations of physicians and epidemiologists (Burkitt and
Trowell 1975, Burkitt 1983).It is postulated that a high intake of
fibre – containing foods is directly related to or is associated
with a low incidence of many disorders and diseases common
with a western lifestyle (e.g., chronic bowel diseases, diabetes,
coronary heart disease, obesity and colon cancer).

6.  ANALYTICAL FIBRE FRACTIONS
 Total fibre – it is the aggregate amount of fibre in a food
product. In other words total fibre is the sum of dietary fibre
and functional fibre.
 Functional fibre – it consists of isolated or purified
nondigestible carbohydrates that have beneficial physiological
effects in humans. It is also referred to as “isolated” or “novel”
fibre mostly from animal sources. Cellulose, chitin, beta
glucans, gums, inulin, oligofructose, fructoligosaccharides,
lignin, pectins, psyllium, and resistant starches are forms of
functional fiber when added to foods.

7.  Crude fibre (CF) - It is the residue of plant food left after
extraction with solvent, dilute acid and dilute alkali (Williams
and Olmstead, 1935). Crude fibre is only 1/7 to ½ of total
dietary fibre.
-whereas crude fiber is the material that in chemical analysis
remains after vigorous treatment with acids and alkalies
(Mehta and Kaur 1992)

8.  Total dietary fibre (TDF) - refers to total amount of
nondigestible (unavailable) material naturally occurring in
foods and mainly of plant origin and it includes fiber from
foods such as whole legumes, vegetables, fruits, seeds and
nuts, undigested products, and undigested biosynthetic
polysaccharides.

12. Hemicellulose Cellulose
 Present along with cellulose in
almost all plant cell walls.
 Cellulose is an important structural
component of the primary cell wall of
green plants.
 Hemicellulose has a random,
amorphous structure with little
strength. It is easily hydrolyzed
by dilute acid or base as well as
myriad hemicellulase enzymes
 Cellulose is the most abundant
organic polymer on Earth.
Hemicellulose and Cellulose

13. Cellulose Hemicellulose Gums Lignin Pectin
 Whole
wheat flour
 Brans
 Cabbage
Family
 Apple
 Root
Vegetables
 Brans
 Cereals
 Whole
grains
 Oat meal
 Dried beans
 Other
Legumes
 Wheat
 Mature
vegetables
 Apple
 Citrus
fruits
 Straw berry
Dietary fibre components & their Sources

14. Physico-chemical Properties

15. Chemical composition of dietary fibre
 Dietary fibre is made up of 3 components.
 The largest component consists of polysaccharides or plant
fibres such as bran, pectins from fruits and vegetables, various
gums and beta-glucans from oats and rye.
 The second – largest component is lignin, which is made up of
poly-phenyl-propane molecules and found in stalks and stems
of plant products.
 The third component includes resistant starches and non-
digestible oligosaccharides. The heterogeneity of dietary fibre
is the primary reason for the diversity of its physiological
effects.

16. Dilute acid
• Cellulose
Dilute alkali
•Cellulose
•Hemicellulose
•Lignin
Water
•Cellulose
•Pectin
•Gums
Solubility

17.  Although solubility of fiber was thought to determine
physiological effect,
More recent studies suggest other properties of fiber,
like fermentability or water Holding capacity or
viscosity are important parameters.
 High-fiber diets provide bulk, are more satiating,
and have been linked to lower body weights.

18. Water holding capacity is generally influenced by
 Chemical composition
 Physical structure
 Particle size
It is Highest for Wheat bran
Water Holding capacity

19.  Water soluble dietary fibre contributes to the
viscosity
 Added to the food as thickeners
Viscosity

20. The non-digestible fructo-oligosaccharides (FOS)
fibres
 Help keep the digestive tract healthy by nourishing
and promoting friendly bacteria (Bifidobacteria,
Lactobacilli).
 These microbes use some of the "prebiotic fibres,” in
the food as fuel for their own growth, and through
their own metabolism produce molecules called
short-chain fatty acids (SCFA).

21.  SCFA production by these microbes has been
associated with a decrease in cancerous colonic cells,
reduction of serum cholesterol, and maintenance of
healthy blood sugar levels and healthy intestinal tract
cell walls.
 Natural food sources of FOS include onions, garlic
and asparagus.
 FOS helps to heal irritable bowel syndrome by
exerting a regulatory action on bowel movement.

22. Recommended dietary intake
 The American Dietetic Association (ADA)
recommends an intake of 20 to 30 g fibre/day for
adults.
 The World Health Organization (WHO) recommends
an upper limit of 40 grams of dietary fibres a day.

23.  Experts hypothesize that primitive diets contained between 80
and 250 grams of dietary fibre/ day (Sobolik 1994, Dreher
2001), Whereas
the mean dietary fibre intakes of the present are only
13 -18g/day (Institute of Medicine, 2002)
 The average daily intake of fibre in the United States is about
12g/day.
 The average daily intake of dietary fibre in the United
Kingdom is around 12g/day in both men and women
 In the developing tropical countries, the dietary fibre intake of
people eating rice as a staple food (India, China, South
America) are similar to Western intakes.

24.  The adequate intake (AI) of total dietary fibre for children,
adolescents and adults was set to 14 g dietary fibre / 1000 kcal
by the Institute of medicine, National Academy of Sciences,
USA.
 The National Cancer Institute recommends an intake of 20 –
30 g fibre/day because it helps to reduce the risk certain types
of cancer.

25.  Cardio vascular diseases
 Diabetes mellitus
 Obesity
 Colon cancer
 Constipation
 Diverticular disease
 Gall stones
 Dermatological disorders
Nutritional and Health Benefits

26.  Because dietary fibre retains its ‘bulk’ as it moves
through the digestive system, it creates a sense of
fullness and satiety.
 The promotion of satiation, lower calorie intake, and
more feelings of fullness play a positive role in
preventing obesity.
 Dietary fibres even control the rate of digestion.

27.  High fibre intakes promote bowel health by
preventing constipation and diverticular disease.
 Dietary fibres positively modulate the colonic
microflora and increase colonic fermentation.
 The production of volatile short chain fatty acids is
used by the microflora to derive energy or for
inhibiting pathogens.

28.  Viscous fibres such as those found in oats and
legumes can lower serum LDL cholesterol levels and
normalize blood glucose and insulin responses.
 Dietary fibres bind to bile salts and they are valuable
in the treatment of recurrent gall stones.
 The binding of dietary fibres with bile acids is
integral to cholesterol homeostasis and fat absorption
 Dietary fibre tends to absorb the intestinal toxins or
carcinogens that build up in the large intestine and
carries them out of the body.

29.  High fibre intake is recommended (20-30g/day) in
irritable bowel syndrome, haemorrhoids, diabetes
mellitus and hypercholesterolemia.
 High fibre intake has a 40% lower risk of heart
disease.
 Some researchers found that increasing fibre intake
decreases the body’s need for insulin.

30.  Some people experience abdominal cramping, bloating or
gas, when they suddenly increase their dietary fibre intake
 Too much of fibre intake may lead to malnutrition and
decreased absorption of minerals
 Another disadvantage of foods rich in fibres is that they
contain a large amount of phytic acid. Phytic acid hinders the
absorption of calcium, zinc and iron.
 Fluid imbalance (leading to dehydration)
Some Disadvantages of High Fibre Intake

31.  Natural
 Processed
 Fibre Concentrates
Food Sources of Fibers

32.  Cereals
 Pulses
 Leafy vegetables
 Roots and tubers
 Other vegetables
 Nuts and oil seeds
 Fruits
Natural Sources

33.  Processing of Food brings about change in the
particle size of fibre
 Water holding capacity also get reduced
Processed Foods

34.  Concentrated forms containing very high TDF (Total
Dietary Fibre)
 Supplement the regular diet with fibre
 Eg: dehydrated fruit and vegetables
 Oat fibre

Fibre Concentrates

35. To Summarise