2. A nutrient is a chemical from outside the cell and that it
needs to perform its vital functions. This is taken by the
cell and converted into a cellular component through a
process called anabolism biosynthetic metabolic or is
degraded to obtain energy and other molecules.
Food is a complex mixture of various substances, which
• To provide sufficient energy & heat for the various
activities & body work.
• In growth, repair & maintenance of body tissues.
• In adding bulk to the diet to keep the digestive system,
3. Classification of Nutrients:
Nutrients can be classified in accordance to their chemical property, to
their function, to their essentiality, to their concentration and to
their nutritive value.
A. According to the chemical nature: The dietary components of
food are classified according to its chemical nature like:
• dietary fiber
• Carbohydrates (sugar and starches) are the most efficient sources of
energy and are known as the “fuel of life.” They are abundantly
found in most plant food sources.
• Complex carbohydrates (starches) are in
breads, cereals, pasta, rice, dry beans and peas, and other
vegetables, such as potatoes and corn.
• Simple carbohydrates are found in sugars, honey, syrup, jam, and
• Each gram of carbohydrate yields 4 calories in the process of its
The main functions of carbohydrates are to;
furnish the main source of energy for muscular work and
nutritive processes, help maintain body temperature, form reserve
fuel, assist in oxidation of fats, and
• Spare protein for growth and repair. In a balanced diet, 60% of our
daily calorie requirement should come from carbohydrates. However
the amount can vary from 50%-70%.
The chief functions of fats are to supply energy and transport fat-soluble
vitamins. Each gram of fat yields 9 calories. Fats are found in both
the animal and vegetable kingdoms.
Fatty acids and glycerol are the end products of the digestion of fats.
Many fats act as carriers for the fat-soluble
vitamins A, D, E, and K. They also act both as a padding for vital
organs, particularly the kidneys, and as subcutaneous tissue to help
conserve body heat.
Fat is stored as adipose (fatty) tissue to form a reserve
supply in time of need. Excess calories from fats may produce
obesity, the forerunner of arteriosclerosis, hypertension, gallbladder
disease, and diabetes. A diet high in fat, especially saturated fat
and cholesterol, contributes to elevated blood cholesterol
levels in many people. Too little fat in the diet may lead to being
underweight, having insufficient padding for the vital organs, and
Butter, margarine, cream cheese, fatty meats,
whole milk, olives, avocados, egg yolks, nuts, commercial
bakery products, and vegetable oils are all sources of dietary fat.
- Proteins are the “building blocks” of the body
And provide important required nutritive elements.
- proteins are needed for growth, maintenance, and
replacement of body cells, repairing worn out tissues and
they form hormones and enzymes used to regulate body
-Animal sources of proteins are of better quality are readily
absorbed & utilized by the body. These include milk & milk
products, eggs, meat, poultry, fish, liver & an exception is
soybean, which is a plant source. Plant sources include
cereals, pulses, dry fruits, nuts, beans etc.
- Daily requirement of protein is 1g/kg body weight.
• Vitamins are essential compounds that are present in
food in minute quantities. Although vitamins do not
furnish energy or act as tissue-building materials, they
do act as catalysts in many body chemical reaction
s and are necessary for normal metabolic functions,
growth, and the health of the human body.
• These are required in very small amounts but are
important for our growth & development. They make
enzymes, which help to progress our body's chemical
• They should be regularly consumed as their deficiency
can lead to diseases such as night blindness, scurvy,
• There are fat-soluble vitamins (A, D, and E&K) and
water-soluble vitamins (B-complex & C).
• mineral elements constitute only a small
portion of the total body weight, they enter into the
activities of the body to a much greater degree than
their weight would indicate.
• These are also needed in small amounts but are important
for our body's basic growth & structure. There are some 50
minerals in our body serving important functions like
formation of bones & teeth, formation of blood, hair
growth, nail growth, skin integrity etc.
• Food sources include - egg, meat, milk, cheese, nuts,
vegetables, beans, banana, orange, melons, salt etc.
9. Dietary Fiber
Special mention must be made with the fibre,
since it is not strictly a nutrient. It is a type of
carbohydrate found in vegetables, fruits, &
whole grains, which absorbs water & increases
bulk of intestinal contents & helps in intestinal
movements. Its deficiency leads to
constipation. It also lowers cholesterol & helps
in weight reduction.
• Water is often called the “forgotten nutrie
nt.” Water is needed to replace body fluids lost
primarily in urine and sweat. Though not a food,
it is an important component of our diets. It is
required for our basic metabolism as serves as a
medium for all chemical reactions, maintains our
body's temperature, helps in nutrition processes
• A daily diet is not complete without consumption
of 8-10 glasses of water. An insufficient intake
may cause dehydration, evidenced by loss of
weight, increased body temperature, and
11. B. According to their function in the body
1. Energy giving foods: The Carbohydrates, fats and
the protein are considered as calorie nutrients
those that serve as metabolic substrate for
energy, so that the body can perform the
necessary functions. The vitamins as well as the
minerals are considered as non-calorie nutrients.
2. Body building foods (Plastic or structural): Foods
such as proteins, fats and carbohydrates are
called as body-building food. They are the
nutrients that form body tissues. Proteins make
up the 20 % or 1/5 of the total body weight. Fat
nutrients make up another 20 % or 1/5 of the
body weight while the carbohydrates make up
12. 3. Protective foods (Regulators): Vitamins and
minerals are the nutrients that function to
regulate body processes. The minerals make
up the 4% of the body weight and the
vitamins make up about 28 grams of the body
weight considering that they are not really a
part of the structural components of the body.
13. C. According to its chemical properties
• According to its chemical properties the
nutrients are further classified into organic and
• Those nutrients that contain the element of
carbon are called as organic nutrients, while
those nutrients that do not contain carbon
element are called as inorganic nutrients.
14. D. According to their essentiality
1. Nonessential Nutrients: which are not vital to
the body and that are synthesized via precursor
molecules (usually essential nutrients).
Therefore, the body does not need regular
intake of such a condition to obtain the
precursors of their environment. These are
produced by the body's metabolism.
2. Essential nutrients: those that are vital to the
body as the body can not synthesize. For
humans, these include essential fatty acids,
essential amino acids, some vitamins and certain
minerals. Oxygen and water are also essential
for human survival, but usually not considered
as nutrients when consumed in isolation.
15. E. According to its mass
Depending on the quantity necessary for cells and
organisms are classified as:
1. Macronutrients: Macronutrients are required
in large quantities daily. These nutrients are
involved as substrates in metabolic processes for
energy. Include proteins, carbohydrates and fats.
They are the basis of any diet.
2. Micronutrients: Micronutrients are needed in
small quantities (usually in amounts less than
milligrams). These nutrients are involved in
regulating metabolism and energy processes, but
not as substrates. They are vitamins and minerals.
16. F. According to its origin
• Depending upon the origin of food it has been
classified as animal food sources and plant
Foods are substances from animal and
plant sources that yield heat and energy
when ingested and absorbed by the
body. Food nutrients build and renew tissues
and regulate the body processes.
17. G. According to its nutritive value
1. Cereals and millets,
3. Nuts and oil seeds,
5. Green leafy vegetables
7. Roots and tubers
9. Milk and milk products
10. Animal foods—meat ,fish,liver, egg, etc.,
11. Carbohydrate foods,
12. Condiments and spices
18. Food group Foodstuffs Nutritional importance
1.cereals and millets Rice, wheat, bajra, jowra, ragi, maize, etc. Rich sources of carbohydrates, air sources of
proteins (6-12%) and B-vitamins and certain
2. Pulses Bengalgram,blackgram,greengram,red gram, peas,
beans masur dhal, etc.
Rich sources of proteins (18-28%) fat (20-60%)
certain B-vitamins and minerals.
3.Nuts and oilseeds Groundout, sesameseeds, cashewnutss, almonds,
walnuts, soybean etc.
Rich sources of proteins(18-28%) ,fat(20-60%)
certain B-vitamins and minerals.
a. green lefay
c. Roots and tubers
Brinjal, beans,cauliflower lady’s finger, pumpkin
,snake gourd ,ash gourd ,plantin ,etc..
Potato ,tapioca,sweet potato,carrot,radish,
Rich sources of carotene (pro-vitamin A) ,
vitamin C, calcium and iron.
Fair sources of vitamin C and minerals.
Good sources of carbohydrates which can be
used as partial substitutes for cereals.
5. Fruit s Amla,guava,papaya,lemon, orange, banana ,mango
and tomato .
Good sources of carbohydrates which can be used
as partial substitutes for cereals
6. Milk and milk products Milk and curds Good sources of nutrients and the most complete
of all foods.
7. Animal foods
Hen’s and duck’s
Rich sources of protein(18-22%) , B-vitamins and
Rich source of protein(18-22%), B-vitamins and
8.carbohydrates White and brown sugars,jiggery,honey,sago,arrow-
root flour and corn flour(custard powder)
These serve mainly as source of energy.
9.fats and oils Ground out oil, coconut oil,gingely oil , butter,ghee
Concentrated sources of energy ,sources of fat
soluble vitamins especially vitamin E. some
(butter,ghee and vanaspathi) also contain vitamin
10.condiments and spices Chilles, tarmind, etc. They have carminative properties and increase
the palatability of foods