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Food and Nutrition
• Food is the main source of energy
• It is essential for us to take food
because of:
energy, growth, repair of body,
protection against diseases, healthy
skin, strong bones, teeth, and blood.
What we eat and why
Food
•Any materials that provides the nutritive
requirements of an organism to maintain
growth and well being.
• Foods are those chemical substances which an
individual takes, digests, assimilates and that
provides the nutritive requirements of an
individual to maintain growth and physical
well being.
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Functions of food :
a. It supply energy for production of heat and for all
types of activities.
b. Essential for growth of human body.
c. Essential for the repair of the daily wear & tear.
d. Protects for body from various types of diseases.
Last in general way, it is involved in the function of
the body processes.
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What’s in food
Food contains a mixture of substances. They are• 1. Proteins
• 2. Carbohydrates
• 3. Fats
• 4. Vitamins
• 5. Minerals
• 6. Water
Calorie value of food :
a) Carbohydrate
b) Fat
c) Protein
- 4.4 k.cal/g.
- 9.3 k.cal/g.
- 4.0 k.cal/g.
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Classification of foods: (with example)
A. According to the source of origin
1. Animal foods
2. Plant foods
B. According to the calorigenicity
1. Calorigenic foods
2. Non- Calorigenic foods
C. According to the main function
1. Energy yielding foods
2. Body building foods
3. Protective foods
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Balanced Diet :
Balanced diet is a diet containing all the
proximate principles of food in adequate and
proportionate amounts; including essential
amino acids and fatty acids for normal growth,
activity, reproduction.
• Adequate : Means the amount that supply the
exat caloriess.
• Proportionate amount : Means presence of
appropriate proportion of food stuffs.
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Criteria of a balanced diet :
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It should contain all the proximate principles of food in
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adequate and proportionate amount.
One third to half of protein
And fat should come from animal sources.
It should contain sufficient fruits and vegetables.
It should be easily digestable , absorbable and assimilable.
It should be easily available.
It should contain certain amount of cellulose to promote
peristalsis.
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Factors considered to formulate a balanced diet:
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Age
•
Sex, height, wt
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Quality and quantity of food.
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Socioecomincal value
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Seasonal factor
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Geographical
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Allergic condition
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Balanced diet chart :
=>
Protein
50 gm
=>
Fat
40 gm
=>
Carbohy drate 310 gm
=>
Green leafy vegetables 100 gm
=>
Fruits
30 gm
=>
Others vegetable
75 gm
=
200 k cal.
360 k cal.
1364 k cal.
25 k cal.
15 k cal .
45 k cal.
2000 k cal
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Factors in relation to Food
The important factors in relation to Food are:
1. Energy Value
2. Quality and Quantity of Primary Foods
3. Variation in the diet
4. Digestibility
5. Cooking
6. Psychological factors
7. Cost
1. Energy Value: The average calorie requirement of adult is
2,400 to 3,000
2. Quality and Quantity of the constituents of Food
(a) Primary Foods (Protein (p), fat (f) and Carbohydrate (c)
 p, f, c are consumed in the ratio of 1:1:4 in this country
3,000 calories are provided by 100gms of p, 100 gms of f
and 400 gms of c.
Although the 1:1:4 ratio is prevalent in this country, still
wide variations of c and f may occur without harm
It is advisable that 10-15% of the total calories should be
obtained from protein, 20-35% from fat and 50-65% from
carbohydrate
What foods do for you
• Proteins
1. Although the expected amount of protein is 100 g per day,
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less amount can also maintain health
Even, 1g per kg body weight may be sufficient
Larger amounts are necessary for growth, pregnancy and
lactation
The requirement of protein in the diet is not only
quantitative but also qualitative aspect is also important
Qualitative aspect of protein is connected with that of its
constituent amino acid i.e. essential amino acid – which
cannot be synthesized by body but has to be given from
out side. Others which can be synthesized in the body are
called as Non essential amino acids
contd.
Proteins (contd)
6. Qualitative aspect of protein is connected with that of its
constituent amino acid i.e. essential amino acid – which
cannot be synthesized by body but has to be given from out
side. Others which can be synthesized in the body are called as
Non essential amino acids
Example of Essential Amino Acids:
Methionine, Tryptohane, Valine, Leucin, Isoleucin,
Phenylalanine, threonine, Lysine
Example of Non Essential Amino Acids:
Proline, Hydroxyproline, Cysteine, Tyrosine
7. Protein gives 4 KCal/g of energy
What foods do for you
FATS:
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1. Fats are high fuel value (9.3 Kcal/g)
2. Increases the palatability of foods
3. Has got high capacity to be stored as energy in the body
4. Fats provide the essential fatty acids such as linoleic acid,
linolenic acid etc.
5. Fats are essential for the absorption of fat soluble protein
6. The consumption of fat usually is over 80 g per day
7. Fat provide fat soluble vitamins i.e. A and D
8. Excess fat result to coronary heart disiease, obesity. Cancer of
bowel and breast
What foods do for you
Carbohydrate:
1. Cheapest source of food.
2. Easily be digested, absorbed and utilized for
producing energy
3. Can furnish 60-80% of the total calorie intake in the
scarcity of proteins and fats
4. Examples of carbohydrates are starch and sugars
5. Carbohydrate provides 4.4 Kcal/g energy
6. Carbohydrates are almost entirely derived from
vagetables
Vitamins:
A vitamin is an organic compound required as a vital nutrient in tiny
amounts by an organism.
Vitamins are classified as i) water-soluble or
ii) fat-soluble.
In humans there are 13 vitamins: i) 4 fat-soluble : A, D, E, and K and
ii) 9 water-soluble (8 B vitamins and vitamin C).
Water-soluble vitamins dissolve easily in water and, in general, are readily
excreted from the body, to the degree that urinary output is a strong predictor of
vitamin consumption. Because they are not readily stored, consistent daily intake
is important. Many types of water-soluble vitamins are synthesized by bacteria.
Fat-soluble vitamins are absorbed through the intestinal tract with the help of
lipids (fats). Because they are more likely to accumulate in the body, they are
more likely to lead to hypervitaminosis than are water-soluble vitamins. Fat
soluble vitamin regulation is of particular significance in cystic fibrosis.
Minerals
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Some minerals are always required
Fruits, vegetables and cereals are
the chief sources of minerals
Milk products supply the majority
of calcium and phosphorous
Calcium:
Increased amount of calcium is
required by children, pregnant and
lactating women
The average intake should be about
800 mg per day
Best sources are milk and cheese.
Other sources are eggs, green
vegetables, oranges, nuts, beans,
carrots eggs
Minerals
Phosphorous:
1. Children should take 1 g per day, adults 1.3 g and a pregnant or
lactating woman 1.9 g
2. Sources of phosphorous are meat, fish, milk, cheese and eggs.
Vegetable foods such as beans, oatmeal and lentils
Iron:
1. Deficiency leads to anemia
2. Sources are bread, meat and potatoes. Also liver, kidney, egg
yolk, green peas, cabbage, carrots
3. Only 10% of iron is absorbed
4. Children up to 12 years require 15-20 mg. daily, adult 40 mg.
and pregnant and lactating women 50 mg
Minerals
Iodine:
1. The daily requirement of iodine is 0.05 mg. and is obtained from water,
vegetables and fish
2. Simple goitre results due to dietary deficiency
Magnesium:
1. The average daily consumption of about 0.2 is sufficient
2. Sources are meat, green vegetables and bread
Copper:
1. The daily requirment is 2 mg.
2. Sources are liver, cocoa, nuts
Sodium Chloride:
1. Usually 20 gm is consumed per day
2. The intake of salt is required only if abnormal quantities are lost e.g. severe
exercise due to sweat; diarrhea
3. Heat stroke is prevented by ingestion of salt solutions instead of water
3. Variation in the diet:
1. There is a risk of missing some essential elements or vitamins in
a varied diet
2. Eskimos live mainly on fish and meat but the poor orientals
chiefly live on rice with small amounts of fish
4. Digestibility of Food:
1. The food is of no use if it is not digested in the alimentary canal
2. Digestibility is more concerned with absorbability
3. When fats and starch are largely used, vegetables and animal
proteins are not absorbed
4. Absorption is more enhanced with a mixed diet that the
substance takes alone
5. Cooking:
1.
In cooking, food is considerably changed. Harmful organisms are destroyed
2.
Cooking makes meat easier for digestion. Overcooking decreases the digestibility
3.
Cooking increases the water content and digestibility of vegetables
4.
Fats are little changed in cooking. Cooking enhances the flavor of the food
5.
When vegetables are cooked, vitamin B2 and C are destroyed
6. Psychological Factors:
1.
Appetite is reduced by worry and anxiety and digestion is also upset due to
imperfect secretion of digestive juices
2.
Consumption of food is increased while taken in pleasant surroundings and good
company with different items
7. Cost:
1.
Dietary food is much influenced by family income
2.
When the income is good, consumption is high with all the protective foods. A poor
income has poor protective foods
3.
The lowest income groups having the low protective foods suffer from rickets and
nutritional anemia.