This document discusses macronutrients and micronutrients and their functions. It classifies nutrients into macronutrients (proteins, carbohydrates, fats) and micronutrients. It describes the functions of each macronutrient in detail, including their roles in the body, food sources, and recommended dietary allowances. Proteins are needed for tissue building and repair. Carbohydrates provide energy and have many metabolic functions. Fats also supply energy, carry fat-soluble vitamins, and aid other bodily processes. A balanced intake of macronutrients from foods like cereals, pulses, vegetables is important for health.

1. Macronutrients
Micronutrients

2. Nutrients and their functions
 Human beings need a wide range of nutrients to
perform various functions in the body and to lead a
healthy life. The nutrients are classified into two broad
categories.
 1. Macronutrients
 2. Micronutrients
 3. Water which is also essential is included as a macro
nutrient.

3.  These nutrients are chemical substances which are
present in the food we eat daily.
 The foods containing these nutrients are classified as
cereals, pulses, nuts and oil seeds, vegetables, milk &
milk products, fruits and flesh foods( fish, meat, and
egg).Most foods contains almost all the nutrients in
various proportions, some foods being rich in certain
nutrients.

4.  Depending on the relative concentration of these
nutrients foods are classified as protein rich foods,
carbohydrate rich foods and fat rich foods.
 Some foods provide a single nutrient as in the case of
sugars which are source of only carbohydrates while
oils, ghee etc provide only fats.

5. Macronutrients- protein,
carbohydrates and fats
 Proteins:
Proteins are vital to any living organism. Proteins are the
important constituents of tissues and cells of the body.
They form important component of muscle and other
tissues and vital body fluids like blood.
Protein supply the body building material.
Protein as antibodies helps the body to defend against
infection.

6.  Rich sources of Proteins:
Animal foods like meat, fish and egg and plant foods like
pulses, oil seeds and nuts.
Soya bean is the richest source of protein containing over
40% of protein.
Requirement of protein
Adult requirement 1.0 gram per kilogram
It is expected children require more protein. 1-2 years child
requires 2.0m grams of mixed vegetable protein per kg.
Pregnant women – 55 grams lactating women- 65 grams.

7.  Deficiencies
Common among weaned infants and preschool children.
These are Kwashiorkor and Marasmas.

8.  Carbohydrates have many important functions in
the body:
1. The primary function of carbohydrates in the body
is to supply energy. Each gram of
carbohydrate, as starch or sugar, provides 4 kcal/g.
Carbohydrates are a source of readily
available energy, which is needed for physical activities
as also the work of the body cells.
The brain and the central nervous system are
dependent on the constant supply of glucose
from the blood to meet their energy needs.

9. 2. Carbohydrates act also as reserve fuel supply in the
form of glycogen, stored in muscles
and liver. The total amount of glycogen in the body is
over 300g. But it must be maintained
by regular intake of carbohydrates at frequent
intervals, so that the breakdown of fat and
protein tissue is prevented.

10.  3. Carbohydrates serve other special functions in the
body. Carbohydrates provide chemical
framework, which combine with the nitrogen to
synthesize non-essential amino acids in the
body.

11.  4. Carbohydrates and their derivatives work as
precursors of important metabolic compounds.
These include nucleic acids, the matrix of connective
tissue and galactosides of nerve tissue.
5. Lactose, the milk sugar, provides galactose needed
for brain development. It aids absorption
of calcium and phosphorus, thus helping bone growth
and maintenance

12.  6. Lactose forms lactic acid in the intestinal track due
to the action of the bacteria (lactobacilli) present
there. These lactobacilli synthesize some of the B-
complex vitamins. It aids, bacteria (lactobacilli)
present to suppress the activities of putrefactive
bacteria and protects us from their undesirable effects.

13.  7. Carbohydrates are an important part of some
compounds, which increase our resistance to
infection (immunopolysaccharides). Ribose, a five
carbon sugar, is an essential part of DNA
and RNA. Carbohydrates are a part of important
compounds, which are components of
nervous tissue (galactolipid), heart valve, cartilage,
bone and skin (chondroitin sulfate).

14.  9. Carbohydrates are needed to prevent dehydration. A low
carbohydrate diet causes loss of
water from tissues as also electrolytes (especially sodium
and potassium) in the urine and can lead to involuntary
dehydration.
10. Dietary fibre acts like a sponge and absorbs water. It
helps smooth movement of food waste
through the digestive tract and the soft, bulky stools are
comfortably eliminated. Food Sources
Carbohydrates are synthesised by plants and occur in
several forms. Starch is found in plant
seeds (cereals and legumes), roots and tubers. These foods
are the primary energy sources in the human dietary

15.  The intake of complex carbohydrate in the form of cereals,
dals and legumes, in normal Indian
dietary is sufficient. Cereals, which are the staple food in
the Indian dietary, contribute major part of the
energy and proteins, and some minerals and vitamins. Dals
and legumes provide significant amounts of
proteins, iron and B-vitamins, in addition to energy.
Potatoes, yams, jackfruit are good source of starch
Carbohydrates in the diet. Vegetables and fruits provide
dietary fibre, minerals and vitamins. Milk is the only
animal food, which is the source of a very important
sugar—lactose—in the diet.

16.  Sugars are found in fruits; the percentage is about
three in melons, ten in citrus fruits and guava
and seventeen in mango. Thus fruits are an excellent
snack food as they are a dilute source of quick
energy and other nutrients.
Sugars found in plant sap or juice (sugarcane and
beetroot) is extracted to give pure 100 per cent
sugar. It must be used judiciously, as it provides only
energy. The intake of foods high in added sugars,
such as soft drinks, syrups and sweets needs to be
controlled to avoid obesity.

17.  Recommended Dietary Allowance
A minimum of 100g carbohydrates are needed in the diet to
ensure the efficient oxidation of fats.
Most diets supply more than this amount. If the
carbohydrate foods are consumed in excess of the
body’s need, the excess is converted into fat and is stored as
reserve. No daily allowance has been
fixed for carbohydrates. As it is the cheapest source of food
energy, it supplies up to 80 per cent of the
calories in the low cost diets in India. If the proteins supply
about 10 per cent of the calories, fat 20 per
cent, then carbohydrates must supply the remaining 70 per
cent calories.

18.  Fats, Oils and other Lipids
There is no precise definition of the word ‘fat’.
 The term is applied to foods which are fatty, immiscible in water
and greasy in texture.
 Every fat molecule has glycerol at its core and three fatty acids
attached to it. The nature of the fat or the oil depends on the
kind of fatty acids linked to the glycerol.
 The hardness, melting-point and the flavour of the fat is related
to the length of the carbon chain and the level of the saturation
of the fatty acid. If the substance is a liquid at 20°C it is called an
oil, if solid at that temperature, it is known as fat.
 Saturated fatty acids are found in solid fats whereas most of the
oils contain unsaturated fatty acids.

19.  The unsaturated fatty acids can be converted to saturated ones,
thus changing the physical and chemical characteristics of the
oil, by a process known as hydrogenation in which hydrogen is
added
on to the oils, in the presence of a catalyst. In the commercial
process, hydrogen is added to some (not all) of the double bonds
of the unsaturated fatty acids to increase the firmness and the
melting point of the product.
 However, this processing also changes the isomers (shape,
configuration) of some of the remaining unsaturated fatty acids.
Most unsaturated bonds in nature are in a ‘cis’ form (folded
pattern), but after hydrogenation, many double bonds are in a
linear pattern, a ‘trans’ form. Thus although they are still
unsaturated, these ‘trans’ fatty acids behave like saturated fatty
acids.

20.  Functions
Fat is a major nutrient and it has several functions. Oils and fats
are concentrated sources of energy. Each, gram supplies 9
calories.
Besides providing energy, oils and fats have several functions in
the body. Food fats are a source of two groups of essential
nutrients — essential fatty acids (EFA) and fat soluble vitamins
A, D, E & K
and their precursors.
 Food fats also aid the transport and absorption of fat-soluble
vitamins. Cholesterol is an essential lipid synthesized in the
liver. Some important hormones and bile acids are formed from
cholesterol. Fat forms the fatty centre of cell walls, helping to
carry nutrient materials across cell membranes.

21. Fats are used to synthesize phospholipids, which are found
in all cells. Fat stored in various parts of the body is known
as adipose tissue. The vital organs in the body are
supported and protected by a web-like padding of this
tissue. Fats act as a cushion for certain vital organs.
Nerve fibres are protected by the fat covering and it aids
relay of nerve impulses. Since fat is a poor conductor of
heat, a layer of fat beneath the skin helps to conserve body
heat and regulate body temperature.
The flavour, palatability and satiety value of foods is
increased by fats. The slower rate of digestion
of fat as compared to carbohydrates results in a feeling of
satisfaction.

22.  Recommended Dietary Allowances
The fat requirement is based on two factors, namely to meet
energy and the essential fatty acids needs. About 10 per cent of
the total energy need is met by invisible fat in the diet.
 A minimum of 5 per cent of total energy needs to be provided as
visible fat in the diet. This works out to about, 12 g of fat
per day. A higher, level of intake of 20 g/day is desirable to
provide energy density and palatability for normal adults.
 It is desirable that an upper limit of 20 g/day of fat intake for
adults and 25 g/day for young children be followed, in view of
the possible complications resulting from excessive intake of fat.
However, in order to meet the essential fatty acid needs, the diet
should contain at least 10 g of vegetable oil, which is a good
source of linoleic acid.