Dietary Fiber and Health

AF3210-Food and Nutrition

AG/2019/080
A.D.K.Nanayakkara
Faculty of Agriculture
Rajarata University of Sri Lanka
What are dietary fibers?
Dietary fiber is the edible part of plant or comparable carbohydrate that is resistant to digestion
and adsorption in the human intestine and ferments completely or partially in the large intestine.
Polysaccharides, oligosaccharides, lignin, and plant compounds are all components of Dietary
fiber. Dietary fiber promotes physiological benefits such as laxation and/or blood cholesterol
reduction.

Dietary fibers are mostly cell wall components such as

non-starch polysaccharides and lignin. These fibers can
be divided into two categories:
 Water-soluble – soluble fiber tend to sow the
movement of food through digestive system.
And Non-water-soluble/ Water-insoluble. –
Insoluble fiber tends to accelerate the movement
of food through the digestive system. Pectin,
gums are examples of soluble fibers. Insoluble
fibers include cellulose, the majority of
hemicellulose (or non-cellulosic polysaccharides), and lignin.

How fiber works?

Soluble fiber absorbs water and transforms into a gel, which binds food, carbohydrates,
cholesterol, and fats in the stomach and transports them through the digestive tract. Insoluble
fibers are largely unaffected by the system. The physiological response to specific fiber can be
understood with the help of the properties such as ( Schneeman, 1999)

Characteristics Response to small intestine Physiological implication

Water dispensability Increase volume in intestinal Sower digestion of
contents; dilution of carbohydrate and lipids, which
compounds. promote nutrient absorption
more distal in the intestine and
is associated with reduction of
plasma cholesterol and
blunting the glucose and
insulin response to a
carbohydrate load and satiety.
Bulk Expand bulk material phase of
contents; alters mixing of
contents.

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Viscosity Slow gastric emptying ; alters
mixing and diffusion.
Adsorb / bind compounds Increased excretion of bile Reduction in plasma
acids and other bound cholesterol.
compounds

Structural aspects of dietary fiber

Dietary fiber consists mostly of polysaccharides, but also of oligosaccharides and plant cell wall
components related with non-starch polysaccharides. The most common characteristic is that
these avoid digestion in the small intestine and reach the large intestine, where a portion
ferments; thus, the intrinsic effect on metabolism and disease risk is likely to be mediated by
their properties as they pass through the gastrointestinal tract. Carbohydrates make up the vast
bulk of dietary fiber constituents: Polysaccharides and oligosaccharides

Polysaccharides' physical properties are influenced by their conformation and interaction with
one another. Dietary fibers' physical characteristics, such as hydration, solubility, rheological
properties, bulk , fermentability, and surface area, significantly impact their physiological role as
digest constituents.

Benefits of fiber
1) Consumption

Because insoluble fiber binds water, making stools softer and bulkier, fiber particularly that
contained in whole grain products is beneficial in the treatment and prevention of constipation,
hemorrhoids, and diverticulosis. Diverticula are pouches of the intestinal wall that can become
inflamed and uncomfortable. A low-fiber diet was formerly suggested for this ailment. Once the
inflammation has reduced, a high-fiber diet yields greater results.

Constipation reduces one's quality of life and raises the risk of colon cancer. Some fibers can
absorb water in our colon, giving our stool bulk. This increased bulk permits our stool to pass
more quickly through our colon, which aids in constipation relief.

2) Lower the cholesterol level

 Low blood cholesterol levels (below than 200 mg/dl.) have been linked to a lower risk of
coronary heart disease.
 The body removes cholesterol by excreting bile acids.
 Because water-soluble fiber binds bile acids, a high-fiber diet may result in increased
cholesterol excretion.
 Some fibers appear to have a stronger impact than others.

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 The fiber in rolled oats is more effective than wheat fiber in decreasing blood cholesterol
levels.
 Pectin has a similar impact in that it, too, can lower blood cholesterol levels.

3) Reduce the risk of some cancers

 Dietary fiber may help reduce the incidence of certain cancers, particularly colon cancer.

 This theory is based on evidence that insoluble fiber enhances the pace at which wastes are
eliminated from the body, implying that the body may be exposed to less hazardous
compounds created during digestion.
 A high-fat, high-protein diet may potentially contribute to the development of colon cancer.
 By trapping bile acids and carcinogenic chemicals, the fiber bulk traveling through the colon
is hypothesized to minimize the risk of pancreatic cancer and colorectal cancer.

4) Useful for losing weight

People who want to lose weight may benefit from high-fiber diets. Fiber offers no calories but
provides a "full" feeling due to its propensity to absorb water. Foods high in fiber sometimes
take more chewing, making it difficult to consume a big number of calories in a short period of
time. This implies we eat less, which may contribute to a decrease in overweight and obesity.
Fibre fermentation and the generation of short-chain fatty acids provide less energy than carbs
like sugars and flour, which may enhance our body's energy balance.

5) Source of fiber

 Only plant foods include dietary fiber: fruits, vegetables, nuts, and grains. Meat, milk, and
eggs are devoid of fiber.
 The fiber content of food may or may not be affected by its form.
 Canned and frozen fruits and vegetables provide the same amount of fiber as fresh fruits and
vegetables.
 However, other forms of processing may diminish fiber content.
 Drying and crushing, for example, degrade fiber's water-holding capacity.
 The removal of seeds, peels, or hulls reduces fiber content as well.
 Whole tomatoes contain more fiber than peeled tomatoes, which contain more fiber than
tomato juice, and whole wheat bread includes more fiber than white bread.

6) Lower risk of digestive condition

High fiber diet may lower the risk of specific disorders such as Heartburn , Gastritis ( acidity) ,
Hemorrhoids (piles) and irritable Bowel Syndrome, etc.

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 7) Lower the risk of Diabetics

Diabetes is characterized by elevated blood sugar levels. DF has a positive impact on blood
glucose (blood sugar). Soluble fiber slows the digestion and absorption of glucose into the blood,
which may help minimize blood glucose oscillations throughout the day. A high-carbohydrate,
high-fiber diet focused mostly on legumes, vegetables, fruits, and whole grains may be especially
beneficial for diabetic patients due to its many impacts on several cardiovascular risk factors,
including postprandial lipid abnormalities.

8) Mental health

The gut-brain axis, or the link between the intestines and the brain, has gained a lot of attention
recently. The gut-brain connections may influence emotional and cognitive processes, for
example, through short-chain fatty acids, which are involved in mental health (for example,
anxiety and depression). The gut-brain interface is well understood to play a function in
determining satiety, mood, and weight.

9) Oral health

Dietary fiber is also beneficial to our oral health. Fibre-rich foods need more chewing in the
mouth, which increases saliva production and cleans our teeth. Preventive effects on dental
caries and dental erosion have been demonstrated, which is not surprising.

10) Gut health and the micro biome

According to recent study on the gut micro biome, fiber diet has a direct influence on the makeup
of bacteria and other microbes in our intestine. The gut micro biota ferments fiber and produces
short-chain fatty acids, which can boost immune system function, increase anti-inflammatory
interactions in the gut, and manage overall energy balance.

11) Cardiovascular diseases

A high-fiber diet has been linked to a lower risk of cardiovascular disease (CVD) and coronary
heart disease; however, the benefit varies depending on the type of fiber consumed. This is due
to the fact that viscous fiber forms a gel in the small intestine, causing us to feel fuller for longer.
Furthermore, short-chain fatty acids produced by gut bacteria are involved in carbohydrate and
fat metabolism, reducing rises in blood glucose and lipids such as cholesterol after meals. They
serve as an energy source for the cells in our colon and safeguard our cardiovascular system.

High intake of dietary fiber lowers the risk of heart disease. In Harvard university study ,
researchers found that a high dietary fiber intake has reduced 40& risk of coronary heart disease.

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 1) Kidney stones

Since fiber can help to regulate blood sugar, it reduce the chance of insulin spikes that can
lead to formation of gallstones and kidney stones.

 Although fiber is vital, it is only one component of a well-balanced diet.

 Excessive fiber consumption may limit the amount of calcium, iron, zinc, copper, and
magnesium absorbed from diets.
 If the amount of fiber in the diet is excessive, deficiencies of these nutrients may occur,
especially in young children.
 Fiber supplements are available in a number of forms, ranging from bran tablets to
refined cellulose.
 Many laxatives labeled as stool softeners are actually fiber supplements.
 The role of fiber in the diet is still being researched.
 Because different forms of fiber play distinct roles in the body, fiber supplements should
be avoided.
 Helps you live longer. Studies suggest that increasing your dietary fiber intake —
especially cereal fiber — is associated with a reduced risk of dying from cardiovascular
disease and all cancers.

Recommendation
1. Include more fiber in your diet, and drink plenty of water. Fibre works by absorbing
water, which helps it travel through the digestive tract.
2. Incorporate fiber into your diet gradually. Increase your intake of fruits, vegetables, and
grains while decreasing your intake of fat and sugar. This minimizes extra calories while
maintaining a sensation of fullness. Remember that a healthy diet is all about making
better food choices.
3. Adding a natural supplement to your daily routine can help you get your 32 grams of
fibre.
4. Make a count! The only way to determine how much fiber you're consuming is to keep a
food diary.

References:

 PowerPoint Presentation (cutm.ac.in)

 What is dietary fibre and is it beneficial? | Eufic
 Dietary fiber: Essential for a healthy diet - Mayo Clinic