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The
importance of food
Joanna
George-Johnson, Contributor
In
the previous lesson, we looked at where food is digested and the enzymes involved.
Today, we will be looking at the importance of the food to our bodies. The
table below shows the uses of the digested food to the body | Food | Product
of digestion | Main
regions of digestion | Use
in the body | | Carbohydrate
(bread-starch) | Sugar/glucose | Mouth
Stomach Small Intestine | Energy | | Protein
(cheese) | Peptides
and amino acids | Stomach
Small intestine | Growth | | Fat
(butter) | Fatty
acid and glycerol | Small
intestine | Energy
store |
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| These
Ascot High School students are revising from a text book at the Portmore Mall
on Friday, October 19. |
The large
intestine (colon) is used to take back the water from the digestive system before
passing out undigested food. The
wholemeal fibre found in wholemeal bread is a form of roughage; it eases the passage
of food through the alimentary canal. It remains undigested by the body. This
undigested food, among other things, pass out of your body as faeces. This process
is called egestion. Vitamins
and minerals do not have to be digested, as they are already small enough to get
into the blood directly. A
balanced diet A
balanced diet contains carbohydrates, proteins, fats, vitamins, mineral salts,
fibre and water. These substances must be present in the correct proportions.
The components in foods have important uses in the body and are obtained from
different sources. | Carbohydrate | Fat
and Oil | Protein
Rich | | | | | Componeut | Use
in the body | Typical
Food source | | Carbohydrates | Provide
energy | bread,
potatoes | | Fats | store
energy, insulate | butter,
oil | | Fibre | provide
roughage | vegetables,
bran | | Minerals | maintain
cells | spinach,
milk, salt | | Proteins | growth
and repair | meat,
fish, cheese | | Vitamins | maintain
cell processes | dairy
food, fruit, vegetables | | Water | cell
and body fluids | fruit
juice, milk, vegetables |
Energy
value of food There
is a relationship between our food intake and the energy we use up. The amount
of food needed depends on age, body mass (biomass) and work done. The energy value
of foods is measured in kilojoules (kJ). A small one-year-old baby needs 3850
kJ daily to maintain body mass and continue to grow, whereas an adult olympic
swimmer in training needs 15,600 kJ daily. When
the amount of food eaten equals the amount of food needed for energy, growth and
repair, the diet is described as balanced. An unbalanced diet with overeating
and lack of exercise can lead to obesity; the diet is also unbalanced if there
is undereating. This is called starvation. Both obesity and starvation are forms
of malnutrition. Check
your understanding Study
the tables of carbohydrate (CHO), fat and protein-rich (P) foods. Then answer
the questions below. 
Questions
1.
Name one food which does not contain any fat. 2.
Name the food that is a good source of protein and also provides substantial carbohydrates.
3. What
groups of food have a high water content? Milk
is an ideal source of food for all developing mammals, including human infants.
Look at the data in the table on different types of milk, then answer the following
questions. | Human
breast milk | Cows'
milk (Whole) | Cows'
milk (Skimmed) | | Energy
kJ/100g | 295 | 276 | 146 | | Protein
% | 1.3 | 3.3 | 3.4 | | Fat
% | 4.1 | 3.8 | 0.1 | | Carbohydrate
% | 7.2 | 4.7 | 5.0 | | Minerals
% | 0.2 | 0.6 | 0.5 | | Water
% | 87.1 | 87.6 | 90.9 |
4.
Which milk has the greatest energy value and why? 5.
Compared with human breast milk, cows' milk has high levels of two particular
food types, and so, should not be given to babies under six months (as it may
cause kidney failure). What are these two food types? 6.
Why is skimmed milk recommended as part of a low cholesterol diet, for people
who are at risk from heart-disease? Joanna
George-Johnson teaches at Ardenne High School.
Email: Masterbio@gmail.com.
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