Dietary fiber or roughage is the indigestible portion of food derived from plants. It has two main components: Soluble fiber, which dissolves in water, is readily fermented in the colon into gases and physiologically active byproducts, and can be prebiotic and viscous.

1. FIBER IN FOODS
Presented by
Dr.T.Poongodi Vijayakumar
Head
Department of Food Science & Nutrition
Periyar University
Salem-11

2. Fiber is the fibrous
material present in plants
and their products like
fruits and vegetables.
Dietary fibre is defined
as that portion of food
derived from plant cells
which is resistant to hydrolysis /
digestion by the elementary
enzyme system in human being.
FIBRE IN FOODS

3. • Dietary fiber (fibre), sometimes called roughage, is the indigestible
portion of plant foods having two main components — soluble
(prebiotic, viscous) fiber that is readily fermented in the colon into
gases and physiologically active byproducts, and insoluble fiber that
is metabolically inert, absorbing water throughout the digestive
system and easing defecation. It acts by changing the nature of the
contents of the gastrointestinal tract, and by changing how other
nutrients and chemicals are absorbed.
• Dietary fiber can be soluble (able to dissolve in water) or insoluble.
Fiber cannot be digested by humans. However, soluble fiber
absorbs water to become a gelatinous, viscous substance and is
fermented by bacteria in the digestive tract. Insoluble fiber has
bulking action and is not fermented, although a major dietary
insoluble fiber source — lignans — may alter the fate and
metabolism of soluble fibers.
• Chemically, dietary fiber consists of non-starch polysaccharides
such as arabinoxylans, cellulose and many other plant components
such as dextrins, inulin, lignin, waxes, chitins, pectins, beta-glucans
and oligosaccharides. The term "fiber" is somewhat of a misnomer,
since many types of so-called dietary fiber are not fibers at all.

4. TYPES OF DIETARY CARBOHYDRATES
Dietary Carbohydrates
Available Unavailable
Simple Sugars /
carbohydrates
Complex
Carbohydrates
Monosaccharide
Disaccharides
Starches
Dextrins
Dietary fiber
(intrinsic and
intact)
Functional
fiber (isolated
and
manufactured)
Water Soluble Water insoluble

5. Categories of Dietary Fiber
• Cellulose, found in bran, legumes, peas, root vegetables,
cabbage family, outer covering of seeds, and apples
• Hemicellulose, found in bran and whole grains
• Polyfructoses (Inulin and Oligofructans)
• Galactooligosaccharides
• Gums, found oatmeal, barley, and legumes.
• Mucilages
• Pectins, found in apples, strawberries, and citrus fruits
• Lignin, found in root vegetables, wheat, fruits with edible
seeds (such as strawberries)
• Resistant Starches, found in ripe bananas, potatoes

6. DIETARY FIBER
• Plant non-starch
polysaccharides
(cellulose, pectin, gums,
hemicellulose, β-glucan,
fiber in oat and wheat
bran)
• Plant carbohydrates not
recovered by alcohol
precipitation (inulin,
oligosaccharides and
fructans)
• Lignin
• Some resistant starch
(RS1 and RS2)
FUNCTIONAL FIBER
Isolated or extracted non
digestible carbohydrates
using chemical,
enzymatic and aqueous
steps of 3-4 degrees of
polymerisation
• Plant (resistant starch,
pectin and gums)
• Animal (chitin and
chitosan)
• Commercially produced
(resistant starch,
polydextrose, inulin,
indigestible dextrins)

10. DIGESTION OF FIBER
FIBER
Anaerobic fermentation by colonic microflora
Short chain fatty acids (Acetate, Butyrate, Propionate)
Reduces pH of the gut
Favorable environment for
probiotic colonization
Fosters the growth of
Lactobacillus & Bifidobacterium
Butyrate –
preferred fuel
substrate for
colonocytes
where it
metabolised to
acetoacetate
and β-hydroxy
butyrate
Acetate and
Propionate enters
into liver and
metabolized into
source of energy;
propionate utilized
by the liver for
gluconeogenesis
and acetate
metabolized
peripherally

11. Products of fiber fermentation
• Volatile fatty acids
– acetate – liver
– Propionate – liver
– Butyrate – colonocytes
• Gases
– Methane – flatus and breath
– Hydrogen - flatus and breath
– Carbon dioxide - flatus and breath
• Energy for microbial growth - feces

12. • When soluble fiber is fermented, short-chain fatty acids (SCFA) are produced. SCFA
are involved in numerous physiological processes promoting health, including:
• stabilize blood glucose levels by acting on pancreatic insulin release and liver control
of glycogen breakdown
• stimulate gene expression of glucose transporters in the intestinal mucosa, regulating
glucose absorption
• provide nourishment of colonocytes, particularly by the SCFA butyrate
• suppress cholesterol synthesis by the liver and reduce blood levels of LDL cholesterol
and triglycerides responsible for atherosclerosis
• lower colonic pH (i.e., raises the acidity level in the colon) which protects the lining
from formation of colonic polyps and increases absorption of dietary minerals
• stimulate production of T helper cells, antibodies, leukocytes, cytokines, and lymph
mechanisms having crucial roles in immune protection
• improve barrier properties of the colonic mucosal layer, inhibiting inflammatory and
adhesion irritants, contributing to immune functions
• SCFA that are not absorbed by the colonic mucosa pass through the colonic wall into
the portal circulation (supplying the liver), and the liver transports them into the
general circulatory system.
• Overall, SCFA affect major regulatory systems, such as blood glucose and lipid
levels, the colonic environment, and intestinal immune functions.[51][52]
• The major SCFA in humans are butyrate, propionate, and acetate, where butyrate is
the major energy source for colonocytes, propionate is destined for uptake by the
liver, and acetate enters the peripheral circulation to be metabolized by peripheral
tissues.

13. Beneficial effects of fiber
• low energy valve ( 1.5 – 2.5 kcal/g)
• increase in stool volume
• Promote laxation, blood cholesterol and blood
glucose attenuation (SCFA – effective inhibitor of
fatty acid and cholesterol synthesis and release
glucose slowly) thereby reducing the risk of non
communicable diseases
• Increases the colonic blood flow
• Lower luminal pH and modulation of the colonic flora
by stimulation of beneficial bacteria and inhibition of
undesirable bacteria
• Viscous fibers reduce the risk of duodenal ulcer by
delaying the gastric emptying

14. Benefits continued….
• prevention of intestinal infection (butyrate down
regulate the activity of transcription factor Nuclear
Factor kappa – B (NF kB) – central regulator of
immune and inflammatory responses)
• prevention of colorectal cancer (low pH depress the
conversion rate of primary bile acids to secondary
and lower their carcinogenic potential)
• improved bio availability and increased mineral
uptake in intestine
• modulation of immune response (produce number of
pro inflammatory cytokines and express the number
of receptors on B and T-lymphocytes and
macrophages required for initiation of immune
response)

15. • Fiber does not bind to minerals and vitamins and
therefore does not restrict their absorption, but
rather evidence exists that fermentable fiber
sources improve absorption of minerals,
especially calcium. Some plant foods can reduce
the absorption of minerals and vitamins like
calcium, zinc, vitamin C, and magnesium, but
this is caused by the presence of phytate (which
is also thought to have important health
benefits), not by fiber.

17. Adverse effect of fiber
• Intake of dietary fiber in excess of 50 grams per day may
cause an intestinal obstruction in susceptible individuals.
In most individuals, however, this amount of fiber will
improve (rather than compromise) bowel health.
• Excessive intake of fiber can also cause a fluid
imbalance, leading to dehydration. Individuals who
decide to suddenly double or triple their fiber intake are
often advised to double or triple their water intake for this
reason.
• In addition, excessive intake of nonfermentable fiber,
typically in supplemental form, may lead to mineral
deficiencies by reducing the absorption or increasing the
excretion of minerals, especially when mineral intake is
too low or when mineral needs are increased such as
during pregnancy, lactation, or adolescence.

18. Drug-Nutrient Interactions
• Dietary fiber, especially the fiber found in fruit, beans, and oat bran,
reduces the absorption of a class of cholesterol-lowering
medications called HMG-CoA reductase inhibitors (for example,
lovastatin) by binding to the drug in the gastrointestinal tract.
• Dietary fiber decreases the absorption of hydralazine, digoxin, and
lithium.
• Diets high in dietary fiber may improve glucose control in people
with type 2 diabetes, thereby reducing the dose of insulin or oral
glucose lowering medications needed to control blood sugar.
• Certain medications, including pain medications (for example,
codeine) and calcium channel blockers (for example, verapamil) can
cause constipation.
• Increased intake of dietary fiber can reduce the constipation caused
by these medications.

19. Safe level of total fiber
consumption
AI for Children
• 1–3 years 19 g/d
• 4–8 years 25 g/d
AI for Boys
• 9–13 years 31 g/d
• 14–18 years 38 g/d
AI for Girls
• 9–13 years 26 g/d
• 14–18 years 26 g/d
AI for Men
• 19–30 years 38 g/d
• 31–50 years 38 g/d
• 51–70 years 30 g/d
• > 70 years 30 g/d
AI for Women
• 19–30 years 25 g/d
• 31–50 years 25 g/d
• 51–70 years 21 g/d
• > 70 years 21 g/d

20. Fiber and calories
• Because soluble fiber is changed during fermentation, it could
provide energy (Calories/kilojoules) to the body. As of 2009
nutritionists have not reached a consensus on how much energy is
actually absorbed, but some approximate around 2 Calories (8.5
kilojoules) per gram of soluble fiber.
• Regardless of the type of fiber, the body absorbs fewer than 4
Calories (16.7 kilojoules) per gram of fiber, which can create
inconsistencies for actual product nutrition labels. In some countries,
fiber is not listed on nutrition labels, and is considered 0
Calories/gram when the food's total Calories are computed. In other
countries all fiber must be listed, and is considered 4 Calories/gram
when the food's total Calories are computed (because chemically
fiber is a type of carbohydrate and other carbohydrates contribute 4
Calories per gram). In the US, soluble fiber must be counted as 4
Calories per gram, but insoluble fiber may be (and usually is) treated
as 0 Calories per gram and not mentioned on the label.

21. RESISTANT STARCH
• RS1 – native starch inaccessible to α-
amylase
• RS2 – native starch accessible to α-
amylase by gelatinization
• RS3 – retrograded starch formed during
cooking, cooling, extruding the starchy
foods
• RS4 – chemically modified starch (starch
esters, starch ethers and cross bonded
starches

22. Points to remember for healthy
life style
• Stop eating fast food
• Drink plenty of water (2-3 liters per day)
• Eat your food slowly
• Eat 3 main meals and 2 small meals per day
• Eat vegetables first in each meal
• Make last meal 3 hours before bed time
• Try to do exercise at least 20 minutes per day

26. With healthy practices and
sustain the ecosystem

27. T H A N K
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