FUNCTIONS OF NUTRIENTS
The foods which we use daily include rice, wheat,
dal, vegetables, fruits, milk, eggs, fish, meat, sugar, butter, oils, etc.
These different foods are made up of a member of chemical components called
nutrients. These are classified according to their chemical composition.
Each nutrient class has its own function, but the
various nutrients must act in unison for effective action. The nutrients found
in foods are --- carbohydrates, proteins, fats, minerals, vitamins and water.
Fiber is also an essential component of our diet. The functions of nutrients
are given below.
Carbohydrates:
Starch
found in cereals and sugar in sugar-cane and fruits are examples of
carbohydrates in foods. The chief function of carbohydrates is to provide
energy needed by our body. Those not used immediately for this purpose are
stored as glycogen or converted to fat and stored, to be mobilized for energy
supply when needed.
Fats:
Oils
found in seeds, butter from milk, and lard from most, are examples of fats found
in foods. Fats are concentrated sources of energy, carriers of fast soluble
vitamins and a source of essential fatty acids. If excess fats are taken in the
diet, these are stored as fat reserves in the body. Energy taken in excess of
body needs, is stored as fat in the body.
Proteins:
Casein
from milk, albumin in egg and gluten in wheat, are examples of proteins
occurring in foods. The main function of protein is the building of new tissues
and maintaining and repair of those already built. Synthesis of regulatory and
protective substances such as enzymes, hormones and antibodies is also a
function of food proteins. About 10 per cent of the total energy is supplied by
proteins in the diet. Protein, when taken in excess of the body’s need, is
converted to carbohydrates and fats and is stored in the body.
Materials:
The
minerals calcium, phosphorus, iron, iodine, sodium and others are found in
various foods in combination with organic and inorganic compounds. Materials
are necessary for body – building, for building of bones, teeth and structural
parts of soft tissues. They also play a role in regulation of processes in the
body, e.g., contraction, clotting of blood, nerve stimuli, etc.
Vitamins:
Fat-
soluble vitamins A, D, E and K and also water – soluble vitamins C and B group
are found in foods. These are needed for growth, normal function of the
body and normal body processes.
Water:
We
get water in foods we eat and a major part from the water we drink as such and
as beverages. Water is an essential part of our body structure and it accounts
for about 60 per cent of our body weight. Water is essential for the
utilization of food material in the body and also for elimination of food
waste. It is a regular of body processes such as maintenance of body temperature.
All individuals need the same nutrients for the same
body function. The only variation is in the amounts of each nutrient
requirement according to age, size, activity, etc. For example, all persons
need energy for work, but a man, who carries loads may need more energy than a
man, who works in an office at a desk job.
As you know, we get the nutrients from the foods and
the beverages we consume. Most foods contain the nutrients in varying amounts.
Let us understand the nutrient composition of the foods we use everyday.
Nutrient
density: It refers to
the quantity of one or more nutrients supplied by a food in reference to
its calorie content. For example, if one compares the protein content of
isocalorie portions of dals, bread and milk, one can see that the dal has the
highest nutrient density for protein, milk next and bread the least.
Food
|
Calories
|
Protein
|
Dal
|
8.5
|
5.5
|
Milk
|
8.5
|
4.0
|
Bread
|
8.5
|
2.4
|
Thus nutrient density is an important aspect to be
considered in selection foods, especially in diets of children, pregnant women,
nursing mothers and in therapeutic diets for patients.
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