Transcript Slide 1 - Food a fact of life

Dietary fibre and water
(Extension)
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Learning objectives
• To know the functions and
sources of dietary fibre.
• To understand the health
benefits of dietary fibre.
• To know the functions and
sources of water.
• To understand the principles
of fluid balance.
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Dietary fibre
Dietary fibre is a diverse group
of carbohydrate found almost
exclusively in plants, including
non-starch polysaccharides
such as cellulose and pectin,
and lignin.
Unlike other types of
carbohydrate, these are not
absorbed in the small intestine
to provide energy, although it
is digested in the large bowel
by bacteria, providing
2kcal/8kJ per gram on
average.
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Sources of dietary fibre
Components of dietary fibre
are found in different
proportions in food, therefore it
is important to eat a variety of
fibre-containing foods.
Dietary fibre is found in:
• wholegrain cereals and
cereal products;
• beans;
• lentils;
• fruit and vegetables;
• nuts and seeds.
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Fibre in the diet
Different types of dietary fibre have
different functions in the body:
• some help prevent constipation
(water intake must also be
increased) to reduce the risk of
diverticulitis and bowel cancer;
• some help maintain normal blood
cholesterol levels;
• some help reduce the rise of
blood glucose after a meal;
• some are associated with feelings
of fullness to help control food
intake, because foods high in fibre
are often low in energy density.
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How much fibre do we need?
Most people do not eat
enough dietary fibre.
The recommended average
intake for dietary fibre is 18g
per day for adults. Children
need proportionately less.
Young children are advised
against consuming too much
dietary fibre as it can make it
too bulky. This may make them
become full before they have
eaten enough food to give
them the vitamins, minerals
and energy they need.
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Fibre on food labels
European regulations on nutrition and
health claims state that a product
claiming to be a ‘source of’ fibre should
contain at least 3g of dietary fibre per
100g, and for a product which contains at
least 6g of dietary fibre per 100g, this can
be labelled as ‘high in’ fibre.
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Can you think of ways to increase fibre in your
diet?
Here are some ideas.
Have a bowl of wholegrain breakfast cereals,
served with a handful of dried fruit.
Switch from white to wholemeal or granary
bread.
Add oats to fruit or vegetable crumble toppings.
Serve a side salad with a sandwich or pasta dish.
Add beans and pulses to casseroles and soups.
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Water
Water is essential for life. It is the
major component of body
fluids and helps to maintain
normal physical and cognitive
functions, as well as the normal
regulation of the body’s
temperature. Water also helps
to get rid of waste substances
in the body.
The body is nearly two-thirds
water, so it is important to
consume enough fluid to stay
hydrated. If we do not
consume enough water, we
become dehydrated.
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Water
Our bodies lose water all the
time, when we go to the toilet,
from sweat and also through
respiration. We need to replace
this water by drinking regularly
to prevent dehydration.
Even mild dehydration can lead
to headaches, irritability and loss
of concentration.
Did you know?
Humans can survive for a few
weeks without food, but they
cannot go without fluids for
more than two to three days.
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Sources of water
Water is provided by food such
as soups, yogurts, fruit and
vegetables (around 20% of our
total fluid intake), as well as
drinks such as milk and juice
(around 80% of our total fluid
intake).
Water is a good choice of drink
because it hydrates without
the provision of energy.
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How much water do we need?
The amount of water and other
fluids that we need to drink
each day varies from person to
person.
The recommendation is to drink
about 6 to 8 glasses of fluids a
day to prevent dehydration. This
is in addition to the fluid we get
from food.
We need to drink more when
the weather is hot or when we
are active.
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What is thirst?
The body’s first response when
dehydration is detected is to signal the
kidneys to conserve water.
The thirst response is initiated when 1-2%
of body mass is lost due to dehydration
so it is important to drink if we are thirsty.
The easiest way to spot that you might
not be getting enough water is if your
urine is a dark yellow colour during the
day. If you are getting enough water
your urine should be a pale straw
colour.
Headache and tiredness are also
symptoms.
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Which population groups may
be at risk of dehydration?
• Older adults may have a
weaker sense of thirst. If
necessary they should be
helped and encouraged to
drink regularly.
• Children need plenty of fluid
and they should be
encouraged to drink regularly,
especially if they are very
active.
• People who are very physically
active should drink enough fluid
to replace the water loss
through sweating.
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What happens if we drink too
much water?
It can lead to ‘water
intoxication’ with potentially life
threatening hyponatraemia.
This is caused when the
concentration of sodium in the
blood gets too low.
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Question
True or false?
All types of dietary fibre have
the same functions.
True
False
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False. Different types of dietary
fibre have different functions in
the body – some help prevent
constipation, some help
maintain normal blood
cholesterol levels.
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Next
question
Question
On average, how much
dietary fibre should adults eat
each day?
10g/ day
14g/ day
18g/ day
22g/ day
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Wrong answer.
Try again
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Next
question
Correct answer.
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Next
question
Question
True or false?
The easiest way to check for
dehydration is by looking at
urine colour.
True
False
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True. If you are dehydrated,
your urine is a dark yellow
colour; if you are getting
enough water your urine
should be a pale straw colour.
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Next
question
Question
What proportion of the body is
water?
About one-third
About one-half
About two-thirds
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Wrong answer.
Try again
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Next
question
Correct answer.
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Next
question
Question
Which of the following is/are
symptom(s) of mild dehydration?
a) Headaches
b) Irritability
c) Thirst
d) Loss of concentration
e) All of the above
a)
b)
c)
d)
e)
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Wrong answer.
Try again
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The end
Correct answer.
The end
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Telephone: 020 7557 7930
Email: [email protected]
Web: www.nutrition.org.uk www.foodafactoflife.org.uk
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