Components of food
Food is a
nutritive substance taken by an organism for growth work, repair and
maintaining life processes. Food is a kind of fuel for the living things.
Just as petrol fuel for our car, in the same way, food is a fuel for our
We must eat to provide us energy s known as staple food. The study of
compositions of food materials and the quantities of food materials required
by our body for growth, maintenance and survival is called Nutrition. A
nutrient is an organic a or inorganic substance required for the survival of
a living being.
Food has many different components and each component is necessary for one
function or the other. The major components of our food are:
The carbohydrates proteins, fats, minerals salts and vitamins are called
nutrients because they are required for the survival of living beings like
human beings. Thus water is an important constituent of our food and makes
up for two third of our body- weight, it is usually not considered a
nutrient. Our diet usually contains the entire nutrient in varying amounts.
For example, egg or meat give us proteins, butter and ghee give us fats,
whereas fruits and vegetables give use minerals and vitamins. We shall now
discus all the components of food in detail, one bye.
are the compound a made up of three elements: carbon, hydrogen and oxygen,
proportion of hydrogen and oxygen being the same as in water (the term
carbohydrates actually means hydrates of carbon)
sucrose, and starch are example of carbohydrates. Carbohydrates are the
main source of energy in our body. Though carbohydrates are not the
trichest source of energy, they are the cheapest source of energy.
The carbohydrates produce energy when they are the oxidized in the body. I
gram of carbohydrates produce kilojoules of energy and about 60 percent to
8- percent of the total energy contained in our diet (or good) comes from
carbohydrates present in it. For a normal person, an about 400-500 gram of
carbohydrate is requiring daily. A growing child, a nursing mother or a
sports man, however, ended more carbohydrate than a cellulose, which forms
the cell wall of plants, is also a carbohydrate, but is not a food this is
because cellulose can not be digested or absorbed in the body. When eaten,
however, cellulose acts as a roughage & help in keeping the intestinal
tract in good working order that is, cellulose helps in the maintaining
healthy digestive system. For example sugar is a type of carbohydrates
which is sweat in taste There are two kinds of sugar simple sugar &
SOURC OF CARBOHYDRATES
carbohydrates in our food are obtained mainly from the plants sources like
wheat, rice maize, potatoes, potatoes, sago (sabu-dana), peas, beans&
fruit. Mile also contains a sugar called lactose. The sugar is also
obtained from food. The world’s three main cereal crops (or starchy food)
which provide us carbohydrates are: wheat rice and maize. In the words,
wheat rice& maize are abundant in starch. Our of these, food from wheat is
prepared in the form of roti, bread. Rice is used as such or in or in
various other form of food products such as rote, bread, noodles, rice,
dosa, idli, potatoes.
esters of long chain fatty acids and an alcohol called glycerol. The fats
are actually made of the same three elements, hydrogen, and oxygen, of
which the carbohydrates are made. The difference lies in the fact that
fats contain less proportion of oxygen as consists of three molecules of a
fatty acid and one molecule of glycerol. Fats are the members of a
heterogeneous group of organic compounds known as lipids. Like
carbohydrates, the main function of fats in the body is to provide a
steady source of energy, and for this purpose they are deposited in
various fat depots within the body and under the skin. In fact, fats
provide twice as much energy as that provided by the same amount of a
carbohydrate. For example, I gram of a carbohydrates on oxidation in the
body during respiration gives about 17 Kilojoules of energy whereas I gram
of a fat (or oil) gives about 37Kilojoules of energy which is more than
double than that given by carbohydrates. The fats provide more energy than
carbohydrates because fat molecules contain higher percentage of carbon
and hydrogen but less percentage of oxygen than that of carbohydrates. Due
to less percentage of oxygen present in it, a fat molecule requires more
oxygen for it combustion and hence produces less heat energy. Form this
discussion we conclude that both, carbohydrates and fats, serve mainly as
sources of energy to our body actually, fats are the richest source of
energy to our body, but they are more expensive than carbohydrates. Fats
can also be stored in the body for subsequent use. The fats present in our
food cannot be absorbed by our body as such because they are complex
organic molecules which are insoluble in water.
Sources of fat
supplied to our body by many foods like butter, milk, egg etc. All
the cooking oils provide us fats The fats which we eat in our food
or dietary fats. All the above given food items contains dietary fats. We
shall now discuss the major fatty acids resent in some common dietary
IN BUTTER :
The major fatty acid present in butter is butyric acid. Butyric acid
is a fatty acid because it contains a single bond.
OIL : The major fatty acid present in coconut oil is octanoic acid. This
is also a saturated fatty acid.
FATS ; The major fatty acid present in animal fat is stearic acid.
IN PLAN T FATS :
The major fatty acid present in plant fats is oleic acid. It will be
good to note here that the fatty acid containing only single bond in there
molecules are called saturated fatty acid.
highly complex organic compound made up of carbon, hydrogen, oxygen and
nitrogen. some of the protein also contain elements such as sulphur and
phosphorus. protein are very important in our food for growth and repair
of the body. In other words, protein are the materials required to build
and repair our body. protein are essential for the growth of the child and
teenagers, and protein are needed for maintenance and making good the wear
and tear of body tissues in adults. In addition to all this,
proteins also supply some energy to the body. Protein are made up of
nitrogen containing compounds called amino acids. Amino acids link
through peptide bonds to fro m protein molecules. There are more than 20
of these amino acids and they all occur in almost all proteins. But
the relative amount of each amino acid present differs in different
proteins. Most of the proteins which are required to perform
different function in our body are prepared with in the body form the
unbounded amino acids.
It should be
noted that the proteins consumed in our food are not used by our body in
their original from. This is because of tow reasons. Firstly
because proteins are insoluble in water and secondly because they are very
complex molecules. We shall now describe what happens when a
protein-containing food is consumed by us. When the food is digested
in small intestine, the proteins present in the food are broken down into
simpler substances called amino acids. The amino acids are water
soluble and less complex molecules. The amino acids thus formed are
absorbed from the intestine into the blood. The blood carries these free
amino acids to the various body cells where they are regrouped to form
specific proteins such as skin, muscle, blood & bones.
Some Important proteins and their Functions
or function of food proteins depend on the amino acids of which they are
made some proteins contain all the amino acids required by our body where
as others contain only some of them. Some of important type of
proteins required by our body is; Enzymes, Hormones, Transport proteins,
contractile proteins, structural proteins & Protective proteins.
The function of enzyme proteins is to catalyzed the biochemical reaction
like digestion taking place in the body. Pepsin & trypsin are enzyme
The function of hormone proteins is to regulate the various body
functions. Insulin is a protein hormone.
function of transport proteins is to carry different substances from the
blood the various tissues of the body. Hemoglobin is an example of
function of contractile proteins is to help in the contraction of
muscles and other cells -- of our body. Myosin and Actin are
The function of
structural proteins is to from the structural elements of the cells and
tissues of our body. Collagen is an example of structural proteins.
function of protective proteins is to help fight infection in our body.
Gamma globulins present in blood is an example of protective proteins.
SOURCES OF PROTEINS
We can get
proteins from plant sources as well as animal sources. Some of plant
proteins are; Ground-nuts, Beans, Whole Cereals like
Wheat and Maize,
and Pulses. Some of the best sources of animal proteins are; Lean
Meat (meat without fats), Fish, Eggs, Milk and Cheese. These are all
body building foods. The most valuable proteins are found in milk,
eggs. They contain all the amino acids required by our body.
These proteins are particularly need by children.
OF FOOD; -
Most of the foods contain all the major nutrients like
carbohydrates, fats, proteins but in the varying amounts. Some foods
contain more of carbohydrates where as others may contain more of fats.
So, by eating a variety of different foods, we can ensure that our body
gets all the essential nutrients in adequate quantity. The amount of
major nutrients like carbohydrates, fats and proteins in some the common
food item is given below;
Ground nut is
however, one food which contains a good percentage of the three major
nutrients, carbohydrates, fats, as well as proteins. In this
respect, ground-nuts is a more nutritious food than wheat because wheat
contains some proteins but very little fats.
FUNCTION OF THE DIGESTION PROCESS
So far we have
discussed that the major nutrients of our food are carbohydrates, fats &
proteins. It is important to note here that the foods which we
consume are not used by our body cells in there original form. This
is because of the fact that most of the ingredients of our body are
complex molecules which are insoluble in water, & and hence cannot be
absorbed by the blood as such.
function of the digestion process is to convert the food that we eat in
the such a form which can be easily absorbed & assimilated by our body.
This point will become more clear from example. Our food contain
mainly carbohydrates, fats & proteins, which are all complex organic
compounds insoluble in water and hence cannot be absorbed by the blood
directly & assimilated by our. During the digestion process,
carbohydrates, fats and proteins undergo mechanical and chemical treatment
due to which they are spilt into simpler water.
metals, non metals & their salts are called minerals because they are
mined form the soil, ground and the earth. Our body needs minerals for its
proper functioning, normal growth and good heath. Minerals are needed to
build bones, teeth, formation of red blood corpuscles, and coagulation of
blood, functioning of muscles, never & thyroid gland etc. Several minerals
are needed to enzymes to do their work. Some of the important minerals
needed by our body are: iron, iodine, calcium, phosphorus, sodium
potassium., Zinc, copper magnesium chlorine fluorine and sulphur. the
deficiency of minerals in the body causes many diseases. Minerals,
however, do not supply any energy to our body. They are essential for the
metabolic activities of the contraction for certain tissues our body can
use minerals in the compound from and not as pure elements. For example,
we can not leat sodium metal or chlorine gas in their element from as
such; because they are toxic (poisonous) and can even kill a person. But
their compound called sodium chloride is a mineral salt which is harmless
and, in fact, essential for our body. We get most of the minerals form
plant sources. This is because plants take the various minerals form the
soil through their roots and supply them to man and animals through the
food chain. So, even the minerals which we get from some animals are, in
fact, derived form the plants which the animals eats.
are the complex organic compounds found in some foods which are necessary
for the well-being of the entire body. Vitamins are necessary for
normal growth, good health, good vision, proper digestion, healthy teeth,
gums, and bones, and for life to be maintained. Vitamins act as
catalysts in certain chemical reaction of metabolism in our body, which
laid to normal growth and good health. Vitamins do not provide
energy to our body, so in this respect they differ from carbohydrates and
fats which provide energy. Though vitamins are needed by our body in
minute quantities but their presence is essential in our diet.
were discovered their chemical composition were not known immediately, so,
initially, the vitamins were represented by letters like A,B,C,D, etc.
More than 15 vitamins are known at present and each one of these is needed
for a specific purpose is the body. Some of the important vitamins
are; vitamin A, Vitamin B, complex, vitamin C, vitamin D, Vitamin E, and
Vitamin K. Most of vitamins cannot be made by body, so they have to supply
through various foods which contain them. Only two vitamins called vitamin
D and vitamin K can be made in our body.
All the vitamins are prepared in plants. Al most all the food items
contain more than one vitamin in varying amounts. These days,
however, all the vitamins are also being produced synthetically. It
should be noted that unlike carbohydrates, fats, and proteins, the amount
of minerals and vitamins needed in our diet is not large, but we must have
them in the diet is not large, but we must have them in the died since the
body does not make these substance.
Some of vitamins
are soluble in water whereas others are soluble only in fats or oils, so,
on the basis of their solubility, all the vitamins can be divided into two
classes or two groups; water soluble vitamins and fat soluble vitamins.
soluble vitamins are;- vitamin B-complex and Vitamins C
soluble vitamins are;- Vitamin-A, Vitamin-D, Vitamin-K Vitamin-E
Called pernicious anemia. The various source of this vitamin are : meat,
liver milk & eggs etc.
name of vitamin c is ascorbic acids. It is a water soluble vitamin.
Vitamin C is necessary for keeping teeth, gums & joints
healthy. It is also increase the resistance of our body to infection &
help fight diseases. The various source of vitamin c are amla ,
lime, orange & tomatoes.
VITAMIN - D
name of vitamin D is calciferol. Vitamin D is a fat soluble vitamin .
Vitamin d is necessary for the normal growth of bones & teeth
because it increase the absorption of calcium & phosphorus
into the body. The various sources of vitamin D are : milk, fish ,
egg & butter. Vitamin D are also produced in our body when the
skin is exposed to sunlight.
VITAMIN - E
The chemical name of Vitamin E
is tocopherol. It is faamily: Times New Roman">The chemical name of
Vitamin E is tocopherol. It is fat soluble vitamin. Vitamin E is necessary
for moral reproduction, normal functioning of muscles and protection of
liver. The various sources of vitamin E are: green leafy vegetables, milk,
butter, tomatoes and wheat germ oil.
Vitamin K is a fat soluble
vitamin which is known as phylloquinine. Vitamin K is necessary for the
normal clotting of blood and preventing hemorrhage. The various sources of
vitamin K are: green leafy vegetables like spinach, cabbage, tomatoes and
Important body minerals, their
function and sources:
Though our body requires a
large number of minerals, but the more important once are: Iron, Iodine,
Calcium, Sodium, and potassium.
: iron is the mist important
mineral required by our body. Iron is needed to prepare a protein called
Hemoglobin present in blood. This hemoglobin helps us in transporting
oxygen form the lungs to the body cells through the blood. Some of
major sources of iron are: Liver, Kidney, bajra ragi, eggs etc.
Iodine is another important minerals needed by our body. Iodine is needed
small quantities for the preparation of thyroid hormone called thyroxin.
Some of the major sources of iodine are: fish sea-food, and iodized salt.
Calcium salts are required for making bones and teeth, to help blood
clotting, and for the proper working of the muscles. The major sources of
calcium are: Milk, Milk products, Like Cheese, Beans, Green leafy,
vegetables, whole gram meat, fish, ragi etc.
phosphorus are also require for the formation of bones and teeth.
Phosphorus is also require for the conversation of carbohydrates in
energy. Phosphorus is important because it is a compound of A.T.P.,D.N.A.,
R.N.A. The major sources of phosphorus are: Milk, Vegetable, Bajra, Ragi,
Water is an inorganic substance made up of hydrogen & oxygen. Water is not
considered a food because it does not give energy like carbohydrates &
fats or builds body tissues like proteins. Water is however, an essential
part of a man’s diet because it helps in preparing food for assimilation
by the body. Water is present in the cell protoplasm, blood plasma & in
the intercellular fluid in the tissues. In fact, about two – third
of a man’s body weight is the water in the tissues of his body. Water
place an important role in a large number of process like
digestion, transport & helps in regulation of body
Water is the solvent for all
the salts in the body and it is the medium which all chemicals reaction
take place in the body. Water is a good solvent so it dissolves the
food nutrients which can then be absorbed or digested by the body. Water
acts as a solvent for transporting dissolved food materials from the
digestive tract to the blood. Water also dissolves the waste material of
our body and hence provide a good medium for excreting body wastes. An
important role of water in our body is to regulate the body temperature
the process of sweating and evaporation. when the outside temperature is
high, the water oozes out through the skin in the form of sweat. when this
water evaporates from our body, it takes the latent heat of vaporization
from skin. By losing heat, the skin cools down a little and we feel
comfortable. The survival time with out water is very short. With out
water, the body cells can not function and they die.
Sources of water in our
The amount of water needed by
body depends on one’s age type of work, and the climate. Our body gets a
lot of water from many of the food items which we eat. For
example, fruits, vegetables, meat and fish give a lot of water to our
body. Most of the water needed by our body, However, comes from the plain
“drinking water “, tea, coffee, milk etc. Some of the water in our body
comes as a by product of the oxidation of glucose during the digestion of
the food. In fact, 1 molecule of glucose on oxidation in the body produces
6 molecules of water.