Egg is a nutritious and inexpensive food that contains balanced amounts of essential nutrients like protein, vitamins, and minerals. It provides high-quality protein and is an excellent source of various vitamins and minerals. The major components of an egg are albumen (egg white) and yolk. Albumen contains over half of the egg's protein and various vitamins and minerals. The yolk contains all of the egg's fat and cholesterol but also provides various important vitamins. Eggs contain antioxidants and other compounds that may help reduce the risk of diseases. Overall, eggs are a healthy and affordable food choice that provides many important nutrients.

1. By
Zaib-Ur-Rehman
Lecturer
Department of Poultry Science
PMAS, Arid Agriculture University, Rawalpindi, Pakistan

2.  To get balanced nutrition it is not necessary to eat
expensive food. Apart from being inexpensive, egg is a
wholesome food which contains balanced amount of
essential nutrients like protein, vitamins and minerals.
All these nutrients are in highly protected form.
Nature has provide the protection to egg, from
deterioration, by egg shell then by shell membranes
and finally by the antibodies present in the egg.

3. Nutritional Composition of an Egg
Nutrient (unit)
Whole
Egg
Weight 60g
Water (percentage) 65-68.5
Calories (kcal) 70
Protein (g) 6.3
Carbohydrate (g) 0.36
Total fat (g) 4.8
Polyunsaturated fat (g) 1
Monounsaturated fat (g) 1.8
Saturated fat (g) 1.6
Cholesterol (mg) 185
Choline (mg) 126
Vitamin A (IU) 270
Vitamin D (IU) 41
Vitamin E (mg) 0.5

4.  Chicken egg is one of the most common foods all over
the world
 Eggs have biological value of 93.79 % comparable
values are 84.5 % for milk, 76 % for fish and 74.3 % for
beef
 Eggs really are the best protein that can be bought by
spending money, and it has all those other valuable
vitamins and minerals too

5.  Its major parts for human consumption are albumin and yolk
 Albumen also known as egg white, Albumen accounts for most
of an egg's liquid weight, about 67%
 Albumen comprises more than half the egg's total protein,
niacin, riboflavin, chlorine, magnesium, potassium, sodium and
sulfur
 The albumen encompasses four alternating layers of thick and
thin consistencies
 From the yolk to external, they are designated as the inner thick
or chalaziferous white, the inner thin white, the outer thick
white and the outer thin white. Egg white tends to thin out as an
egg ages because its protein changes in character.

6.  Yolk or yellow portion makes up about 33% of the liquid
weight of the egg
 It contains all of the fat in the egg and a little less than half
of the protein
 With the exception of riboflavin and niacin, the yolk
contains a higher proportion of the egg's vitamins than the
white
 All of the egg's vitamins A, D and E are in the yolk
 Egg yolks are one of the few foods naturally containing
vitamin D
 The yolk also contains more phosphorus, manganese, iron,
iodine, copper, and calcium than the white, and it contains
all of the zinc.

7.  The yolk of a large egg contains about 59 calories
 Yolk fatty acids have a central role in egg nutritional
properties evaluation
 The yolk weight of a typical chicken 60g egg is 20g, of
which 50% is solid matter and 50% is water; it contains
6g of lipids and 3g of proteins
 Egg lipid classes are: Triacylglycerol’s (65%),
Phospholipids (28.3%), Free Cholesterol (5.2%),
Cholesterol ester and free fatty acids (traces).

8.  The term “cholesterol” refers to a group of chemicals
containing both protein and fat components
(lipoproteins) that are present in every living cell and
perform following functions.
 Aids in hormone production.
 Essential for brain and nerve development.
 Starting material from which the liver produces bile
acids, necessary for digestion of fats.
 Key substances in the wall of every cell.
 Precursor for production of steroid hormones by the
adrenal glands and gonads.

9.  They are an essential component of all cells in the body of
chickens, humans and all animals
 They do not occur in plants
 Cholesterol content of eggs became an important issue for
consumers in the 1970's and 1980's when it was discovered that,
among the human population, those with high cholesterol levels
in their blood (usually referred to as “serum cholesterol”) were at
greater risk of heart attacks and/or atherosclerosis
 While this statistical connection is an important one in terms of
human health, there have been decisive slipups in its
explanation. There is effectively no link between the cholesterol
most people consume in their diets, and their serum cholesterol
levels (Hu et al., 1999).

10.  There are two types of cholesterol, Low density lipoproteins
(LDL) and High density lipoproteins (HDL)
 Low density lipoproteins also called bad cholesterol carry most
of the cholesterol in the blood. The cholesterol and fat from the
LDLs are the chief source of dangerous build up and obstruction
in the arteries. Thus, the more LDL cholesterol in the blood
causes the greater chance of heart diseases
 Nature has provided good cholesterol (HDL) in the egg yolk, it is
in minute quantity but very effective
 High density lipoproteins also named as good cholesterol, this
cholesterol goes back to liver, which leads to its removal from the
body so HDLs help to keep cholesterol from building up in the
walls of arteries, if level of good cholesterol is low, risk of heart
diseases is greater
 Egg yolk consist of 68 percent LDL and 16 percent HDL.

11.  The commonly used drugs to lower blood pressure stop the
production of the hormone angiotensin to narrowing the body's
blood vessels
 The scientists identified several different peptides in boiled and
fried eggs that act as potent Angiotensin Converting Enzyme
(ACE) inhibitors
 The scientists showed that enzymes in the stomach and small
intestine produce these peptides from eggs
 The protein produced by stomach enzymes after coming in
contact with eggs acts in the same way as blood pressure
lowering drugs
 In conclusion eggs do not have any side effect on heart, blood
pressure and serum cholesterol; and are safe in every aspect.

12.  Chicken eggs are abundant in antibodies such as IgY which can
treat human rotavirus, Escherichia coli, streptococcus,
pseudomonas, staphylococcus and salmonella infections.
 The nutritionally balanced, high biological value of the egg is an
excellent growth promoter in children
 It is the best natural nutritional support for convalescents,
especially those with tuberculosis or AIDS related infections.
Lipoprotein and other high biological value proteins in the egg
act as excellent growth promoters in children and animals.
 Egg albumen can be used as an remedy in cases, where certain
toxins and irritants may have been accidentally consumed. It
protects the mucous membranes of the stomach and intestine,
and prevents ulcer formation.

13.  Studies carried out at Japan's Kyoto University have revealed that egg
contain the two substances—Lumiflavin and Lumichrome. These two
substances, along with sulphoraphane, have the ability to restrict the
multiplication of cancer-inducing viruses and also prevent the change
of normal to cancerous cells. These compounds are also natural
antioxidants.
 The Gl-globulin lysozyme, the G2 and G3-globulins,
ovomacroglobulin, antibody "IgY" as well as other natural
antimicrobials and immunostimulants in the egg may prolong the lives
of those with AIDS, not only due to their high nutritional value but also
because of their antimicrobial properties.
 Egg yolk and albumen chalaza are rich sources of "sialic acid,” which
has powerful antimicrobial, anti-inflammatory and antiviral properties,
and hence is used in the cure of Helicobacter pylori and other
microbial infections causing ulcers, colon cancer, gastritis and enteritis.

14.  Lutein and zeaxanthin from eggs helps in maintaining the eye health
and reducing the risks of age-related macular degeneration, a major
cause of irreversible blindness.
 Vitamin E, organic selenium and other antioxidants in functional eggs
prevent oxidation, ageing, and formation of plaques in arteries.
 The high-quality protein in eggs helps you to feel (prolong a feeling of
fullness) full longer and stay energized, which contributes to
maintaining a healthy weight.
 A single egg contains 50 % of your daily required intake of Choline
which is essential for normal functioning of all cells, including those
involved with metabolism, brain and nerve function, memory, and the
transportation of nutrients throughout the body. Choline also helps to
prevent birth defects, as well as helps promote brain and memory
development in infants.

15.  Different vitamins and minerals play a very important role
in the body which are as follows
 Riboflavin: Helps to produce energy in all the cells of the body
 Pantothenic Acid: Helps to breakdown food and assists body cells in
producing energy.
 Phosphorus: Essential for healthy bones, teeth and cell membranes.
Phosphorus is also required for energy production in the body. It is
also essential for healthy bones, teeth and cell membranes.
Phosphorus is also required for energy production in the body.
 Vitamin D: Works with calcium to strengthen bones and teeth.
 Calcium: Helps to build and maintain strong bones and teeth. This
mineral also plays an important role in nerve function, muscle
contraction and blood clotting.

16. Importance of Egg
 Hen eggs are an important source of nutrients and a major
source of active molecules
 Modification of the nutrient content of the egg by
modifying the diet of the hen has led to “ designer eggs ”
that serve as functional foods and nutraceuticals
 With a hen laying more than 300 eggs per year, and with
the vast infrastructure of the layer industry housing more
than 100,000 hens, the hen holds great promise as a low -
cost, high - yield bioreactor of active molecules usable by
the food, pharmaceutical, and cosmetic industries.

17. Importance of Egg
 Eggs from all species of poultry consist of 52 – 58%
albumen, 32 – 35% yolk, and 9 – 14% shell and its
supporting membranes
 The egg contains all the essential components, such as
proteins, lipids, vitamins, minerals, carbohydrates, and
growth factors required by the developing embryo
 Egg components have been attributed diverse
biological activities, including antimicrobial and
antiviral activity, protease inhibitory action, vitamin -
binding properties, anticancer activity, and
immunomodulatory activity

18. Importance of Egg
 Albumen proteins identified to date belong to several functional
protein families, including serpin, transferrin, protease
inhibitors Kazal, glycosyl hydrolases, lipocalin, bacterial
permeability - increasing protein, clusterin, cysteine protease
inhibitor, VMO - 1, and uPAR/CD59/Ly6/snake neurotoxin folate
receptor (Gu é rin - Dubiard et al. 2006 ).
 Proteins in the egg white occur both as free and conjugated
forms. The latter are formed when the protein is modified by
prosthetic groups such as lipids and carbohydrates to yield
lipoproteins and glycoproteins, respectively (Kovacs - Nolan et
al. 2005 )
 The major egg white proteins include ovalbumin, ovotransferrin
(conalbumin), ovomucoid, and ovomucin. Other egg white
proteins include lysozyme, ovoinhibitor, ovomacroglobulin
(ovostatin), cystatin, and avidin (Sugino et al. 1997 )

19. Biological Activities of Egg White
Components