Proteins are made up of amino acids and perform many essential functions in the human body. They are classified based on their structure as simple, conjugated, or derived proteins and based on quality as complete, partially complete, or incomplete proteins. A balanced diet containing proteins from sources like eggs, milk, and legumes is important for growth, maintenance, and repair of tissues. Deficiencies can cause conditions like kwashiorkor while excesses place burden on organs and increase calcium loss.

2. Presented by
Preeti shukla
Lecturer, RCN, Kanpur

3. Introduction
• Protein are large, complex, organic compounds made
up of carbon, hydrogen, oxygen and nitrogen. The
basic units of proteins are the amino acids. Each
amino acid contains an acidic an acidic group and an
amino group. Proteins consist of chains of amino
acids that are linked to each other by a peptide
linkage.

4. Amino acids
• Proteins are made up of small units called
amino acids. Some 24 amino acids are stated
to be needed by human body of which 9 are
called essential amino acids because our body
can not synthesize them in required amounts.
So they must be obtained from dietary
proteins.

5. +
• Classification of proteins-
1- On the basis of their structure
2- On the basis if their quality
Classification by structure-
1- Simple proteins- these proteins are made up of
amino acids only, e.g- zein in corn, albumin in egg
white and globulin in hemoglobin, etc.
2- Conjugated proteins- these are the proteins which
are combined with a non protein molecules. E.g-
hemoglobin (protein + hem), mucin (protein +
carbohydrate) and lipoprotein (protein + lipid)

6. 3- Derived proteins- these are produced by the
actions of acids, alkalies, heat and enzymes on
native proteins, e.g- Peptones and polypeptides are
formed when digestive enzymes begin their action
on proteins.
Classification by quality-
1- Complete proteins or first class proteins- these
proteins contain all essential amino acids in sufficient
proportion and amounts to meet the body’s need. they
are found in animal foods. This protein also called
biological complete protein. Ex- Eggs, milk, fish and
poultry are complete protein foods.

7. Partially complete proteins or second class proteins-
they do not contain all the essential amino acids in
required amount. They are capable of maintaining life
but cannot promote growth. They are found in plant
food. Cereals, pulses, nuts and oil seeds are partially
complete proteins foods.
• Cereals contain inadequate amounts of essential
amino acid lysine and pulses are deficient in
methionine.
Incomplete proteins- they are deficient in a lot of amino
acids and are incapable for growth and repair of body
cells. They maintain life. One or more essential amino
acids may be completely lacking.

8. Function of protein
Important functions of proteins are as follows:
1. Growth and Maintenance-Under normal circumstances,
your body breaks down the same amount of protein that it
uses to build and repair tissues. Other times, it breaks down
more protein than it can create, thus increasing your body’s
needs.
• This typically happens in periods of illness, during
pregnancy and while breastfeeding

9. 2. Causes Biochemical Reactions
• Enzymes are proteins that aid the thousands of
biochemical reactions that take place within and
outside of your cells.
• The structure of enzymes allows them to
combine with other molecules inside the cell
called substrates, which catalyze reactions that
are essential to your metabolism.
• Enzymes may also function outside the cell,
such as digestive enzymes like lactase and
sucrose, which help digest sugar.
• Some enzymes require other molecules, such as
vitamins or minerals, for a reaction to take
place.

10. • Bodily functions that depend on enzymes
include (9Trusted Source):
Digestion
Energy production
Blood clotting
Muscle contraction
• Lack or improper function of these enzymes
can result in disease

11. 3- Acts as a Messenger
• Some proteins are hormones, which are chemical
messengers that aid communication between your
cells, tissues and organs.
• They’re made and secreted by endocrine tissues
or glands and then transported in your blood to
their target tissues or organs where they bind to
protein receptors on the cell surface.
• Hormones can be grouped into three main
categories :
Protein and peptides: These are made from
chains of amino acids, ranging from a few to
several hundred.

12. Steroids: These are made from the fat
cholesterol. The sex hormones, testosterone
and estrogen, are steroid-based.
Amines: These are made from the individual
amino acids tryptophan or tyrosine, which help
make hormones related to sleep and
metabolism.

13. 4. Provides Structure
• Some proteins are fibrous and provide cells
and tissues with stiffness and rigidity.
• These proteins include keratin, collagen and
elastin, which help form the connective
framework of certain structures in your body.
• Keratin is a structural protein that is found in
your skin, hair and nails.

14. • Collagen is the most abundant protein in your
body and is the structural protein of your
bones, tendons, ligaments and skin.
• Elastin is several hundred times more flexible
than collagen. Its high elasticity allows many
tissues in your body to return to their original
shape after stretching or contracting, such as
your uterus, lungs and arteries.

15. 5- Maintains Proper pH
• Protein plays a vital role in regulating the
concentrations of acids and bases in your
blood and other bodily fluids.
• The balance between acids and bases is
measured using the pH scale. It ranges from 0
to 14, with 0 being the most acidic, 7 neutral
and 14 the most alkaline.

16. Examples of the pH value of common substances
include :
• pH 2: Stomach acid
• pH 4: Tomato juice
• pH 5: Black coffee
• pH 7.4: Human blood
• pH 10: Milk of magnesia
• pH 12: Soapy water

17. 6- Balances Fluids
• Proteins regulate body processes to maintain fluid
balance.
• Albumin and globulin are proteins in your blood
that help maintain your body’s fluid balance by
attracting and retaining water .
• If you don’t eat enough protein, your levels of
albumin and globulin eventually decrease.

18. • As the fluid continues to build up in the spaces
between your cells, swelling or edema occurs,
particularly in the stomach region .

19. • This is a form of severe protein
malnutrition called kwashiorkor that develops
when a person is consuming enough calories
but does not consume enough protein.
• Kwashiorkor is rare in developed regions of
the world and occurs more often in areas of
starvation.

20. 7- Boosters Immune Health
• Proteins help form immunoglobulins, or antibodies,
to fight infection. Antibodies are proteins in your
blood that help protect your body from harmful
invaders like bacteria and viruses.
8- Transports and Stores Nutrients
• Transport proteins carry substances throughout your
bloodstream — into cells, out of cells or within cells.
• The substances transported by these proteins
include nutrients like vitamins or minerals, blood
sugar, cholesterol and oxygen.

21. 9- Provides Energy
• Proteins can supply your body with energy.
• Protein contains four calories per gram, the same
amount of energy that carbs provide. Fats supply the
most energy, at nine calories per gram.

24. • Digestion and absorption-the digestion of protein
takes place in the stomach and intestine. The
proteolytic enzyme present in gastric juice is called
pepsin. It acts on proteins in an acid medium and
hydrolysis them to simpler compounds known as
polypeptides.
• In the intestine, proteolytic enzyme (trypsin,
chymotrypsin and peptidases) present in the
pancreatic and intestinal juices hydrolyze the
polypeptides to free amino acids.
• The amino acids are absorbed in the small
intestine and enter the blood circulation through
the portal vein. Blood carries them to all parts of
body.

27. Protein metabolism
• The chief use of protein is to provide material for
body building. Protein can also be used as body fuel.
• Excess protein and unsuitable protein are split up in
the liver to form body fuel in the form of glucose and
secondly urea or nitrogenous waste matter.
• This process is known as the deamination of the
amino acids. The nitrrogenous content of the amino
acid is converted first in to the ammonia which for
the most part combines with carbonic acid splits up
into urea water in the liver.

28. • The glucose is either burnt or stored as required. The
urea is readily soluble and being useless for fuel is
carried away by the bloodstream and excreted by the
kideny. The waste products of protein metabolism are
urea, uric acid and creatinine.

29. Effects of deficiency and excess of proteins
• A reduced protein intake over a prolonged
period of time leads to loss of weight, anemia,
nutritional edema, lowered resistance to
infection and poor healing of wounds. Protein
deficiency is more marked during periods
when protein needs are more, e.g- during
infancy, childhood, pregnancy and lactation.

30. • Protein energy malnutrition or protein calorie
malnutrition is common in pre school children
in developing countries like india.

31. • Protein energy malnutrition (PEM)- PEM has its two
clinical forms, kwashiorkor and marasmus. There are
two different clinical picture at opposite poles of a
single continuum.
• Nutritional marasmus- this disease was first reported
in 1935 in Africa by Dr. Cicely Williams. This is
caused by deficiency of proteins only in diet.
Important signs and symptoms are growth failure,
edema, diarrhea, anemia and changes in skin and hair.

32. • Kwashiorkor- this is caused by severe
deficiency of proteins and calories in diet. This
disease is characterized by growth failure, loss
of fat, signs of dehydration and mental
changes, etc.

35. Classification of PEM- protein energy malnutrition is a
spectrum of conditions ranging from growth failure to
kwashiorkor or overt marasmus.
1- Gomez’s classification- it is based on weight
retardation. It locate the child on the basis of his/ her
weight in comparison with a normal child of the same
age.
Weight of age(%)= weight of the child/weight of
a normal child of same age x 100

36. • Weight (kg)= (age in month + 9)/2 – for 1-5
year children.
• Weight (kg)= 2 x (age in years + 5) - for 5-14
year children.

37. Degree of PEM are calculated as follows:-
• Weight between 9.0-110 %= normal nutritional status.
• Between 75-89 % = 1st degree (mild) malnutrition
• Between 60 and 74%= 2nd degree (moderate)
malnutrition.
• Below 60 %= 3rd degree (severe) malnutrition.

38. Other indicators for assessing under
nutrition-
• Malnutrition with retarded growth in which a
drop in the height/age ratio points to a chronic
condition of shortness of stunting.
• Malnutrition with a low weight for a normal
height in which the weight for height ratio is
indicative of an acute condition of rapid
weight loss or wasting.

39. • (A) Weight / height (%)= weight of the child/
weight of a normal child of same age x 100
• (B) Height / age (%) = height of the child /
height of a normal child of same age x 100

40. • Arm circumference- it is a reliable estimation
of the body’s muscle mass but it cannot be
used before the age of one year. Arm
circumference exceeding 13.5 cm is a sign of
satisfactory nutritional status, between 12.5 to
13.5 cm indicates mild- moderate malnutrition
and below 12.5 cm severe malnutrition.

42. • Preventive measures- there is simple solution to
the problem of PEM. Many types of actions are
necessary.
1- health promotion- measures are directed to
pregnant and lactating women ( education and
nutritional supplements)
 Promotion for breast feeding.
 Development of low cost weaning food.
 Improvement of family diet.
 Nutrition education
 Home economics
 Family planning and spacing of birth.

43. 2- Specific protection-
Diet of the child must contain protein and
energy rich foods such as milk, eggs, fresh
fruits.
Immunization against diseases.
Food fortification.
Early detection and treatment.
3- Rehabilitation-
Nutritional rehabilitation services this includes to
prepare nutritious LADDUS or mixture with
following method.

44.  Whole wheat= 40 g
 Bengal grams= 16 g
 Groundnut= 10 g
 Jaggery= 20 g
 Total= 86 g
One laddu will provide 33 kcal and 11.3 g
protein. Give one laddu daily for few weeks
and months.
Hospital treatment in case of severe PEM.
Follow up care

45. Effects of excessive intake of proteins-
• An excessive intake of protein is used as energy
or converted to fat and store in adipose tissue in
body.
• Excessive intake of protein increase the burden on
liver and kidneys to metabolize and excrete the
wastes. If these organs are diseased, toxic wastes
tend to accumulate in the body.
• A high intake of protein increases the loss of
calcium through urine .
• Animal proteins such as meat, poultry and whole
milk products form a substantial part of the high
protein diet.