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The Incredible Egg




  • Human beings require a well balanced diet containing proper amount of proximate principles which include proteins, lipids, carbohydrates, vitamins, minerals and water to enable them to live and thrive. Nutritionists know that all foods contain at least one of these six nutrient groups. Eggs have been regarded as one of nature’s perfect foods.

     

    Human beings require a well balanced diet containing proper amount of proximate principles which include proteins, lipids, carbohydrates, vitamins, minerals and water to enable them to live and thrive. Nutritionists know that all foods contain at least one of these six nutrient groups. Eggs have been regarded as one of nature’s perfect foods.

    The table egg is the most nutritious, yet relatively cheaper natural food having one of the highest digestibility coefficients. Eggs contain all six of these nutrient groups. Eggs are one of the best protected foods available to man in a form originally packed by nature. They cannot be adulterated because of their outer covering or the shell. Their judicious use in the diets can effectively combat nutritional imbalances against the vulnerable groups particularly nursing mothers, infants, children and convalescent persons.

    Both eggs and milk are considered to be the two best protective foods because they are concentrated sources of nutrients viz proteins, energy, vitamins and minerals. When the dietary value of egg is compared with that of milk, we find egg is richer in proteins, fats, vitamin A, B12 , riboflavin and folic acid than milk on per unit basis. Similarly eggs are rich sources of iron which is deficient in milk and other foods except leafy vegetables .Again egg is rich source of vitamin D as compared to milk which is important for bone development for children. Eggs are given in persons suffering from conditions such as Kwashiorkor, anemia, typhoid, tuberculosis; post operative stages, pregnancy etc.

    Eggs contain all the dietary essential amino acids needed by the human being which are needed for the maintenance, growth, repair and production of antibodies that protect us from the diseases .The protein of egg is of such a high quality that the nutritionists use it as a standard for measuring the quality of other food proteins. Thus egg protein is the best available in nature for human consumption with well balanced amino acid profile, having the highest biological value, protein efficiency ratio, net protein utilization, net protein value and chemical score (Table.1)

    Table.1 Protein quality of egg protein in comparison with other foodstuffs.

    Food stuff

    Biological value

    Protein efficiency ratio

    Net Protein utilization

    Chemical score

    Egg

    96

    4.5

    91

    100

    Cow’s milk

    84

    3.0

    75

    65

    Meat

    80

    2.8

    76

    70

    Fish

    85

    3.0

    72

    60

    Liver

    77

    2.9

    65

    66

    Pulses

    56

    1.6

    45

    44

    About 60% of the fat in an egg is in the form of unsaturated fatty acids. These unsaturated fatty acids are often considered better for our health than the saturated fatty acids. Eggs contain very little carbohydrates and no fiber.

    One egg contains approximately 85 calories, which is only 3-4% of the total calorie needs of an adult human being. The fat soluble vitamins A, D, E and K are found in eggs along with the B-complex vitamins. Egg contains no vitamin C. Eggs are also an excellent source of iron, phosphorus, selenium and other minerals. Its nutritional value, chemical composition and % contribution towards daily nutrient requirements are presented in Table 2

    Table2.  Nutrient composition of 100g of egg content and the percentage of daily recommended nutrients contributed by two eggs.

    Nutrient

    Content in 100g of egg contents

    Requirements/day/man

    %contribution by two eggs

    Protein (g)

    13.3

    67

    22.2

    Lipids(g)

    11.4

    50

    76.0

    Ash(g)

    0.8

    0.2

    1.6

    Linoleic acid (g)

    1.8

    12.5

    14.4

    Cholesterol(mg)

    400

    1500-2000

    852

    Energy(Kcal)

    162

    2700

    5400

    Total saturated fatty acids(g)

    3.34

    14.97

    6.68

    Total un- saturated fatty acids(g)

    6.4

    20.45

    13.04

    Calcium(g)

    50

    0.8

    1.6

    Phosphorus(g)

    178

    0.9

    1.8

    Iron(mg)

    1.44

    12

    24

    Vitamin A (I.U)

    634

    5000

    1268

    Vitamin D (I.U)

    49

    400

    98

    Vitamin B1(mg)

    0.062

    1.5

    0.124

    Vitamin B2(mg)

    0.508

    2.0

    1.016

    Vitamin C(mg)

    —-

    75

    ——

    Despite having nutritional supremacy, abundant availability and within the reach of common man, the per capita consumption of eggs in many countries, including India, is far below the minimum recommended level is half an egg per head per day.

    However, the egg has been under intense attack by anti-cholesterol advocates. The egg has been blamed and defamed as one of the major culprits in causing heart problems.

    MYTHS AND MISCONCEPTIONS ABOUT EGGS
    Scientific and logical explanations are given based on the advances made in nutrition, food science and medicine to disprove the above misconceptions.

    I.Egg is a non-vegetarian food and consumption is a sin.
    No doubt the table egg is of animal origin just like milk. But milk is considered as an acceptable food for vegetarians (Lacto- vegetarian), than logically the infertile table eggs also shall be an acceptable food for vegetarians (lacto-ovo-vegetarian). Milk is the secretion of udder primarily meant for feeding growing calves, whereas egg is the secretion of ovary and oviduct to feed the growing embryo (only in case of fertile eggs, incubated for hatching) and not a potion of meat. A table egg is infertile and there is no living cell in a table egg. Hence there is no sin or cruelty in eating table eggs which are infertile and lifeless. If eating lifeless egg is considered as sin, then eating the vegetable and fruits which are obtained from live plans is a great sin.
    Scientific and logical explanations are given based on the advances made in nutrition, food science and medicine to disprove the above misconceptions. Scientific and logical explanations are given below based on the recent advances made in nutrition, food science and medicine to disapprove the above misconcepts
    .

    II.Egg is not suitable food during summer, since it produces excess heat:
    Some people are under the belief that consuming eggs will generate excess heat in the body, hence are not suitable during summer. Probably such persons might have misunderstood its high nutritive value as high calorific value. In fact egg is relatively one of the low energy foods supplying only 81 Kcal of energy per egg or about 162 Kcal/100g of edible portion of the egg, when compared to more than 320Kcal/100g of grains or pulses. Hence egg is ideal food for all seasons and even for those who want a low calorie and /or high protein food. Egg is contaminated with harmful bacteria like Salmonella and E. coli and consumption of such eggs would lead to food poisoning and other diseases.

    III.Egg is contaminated with harmful bacteria and consumption of such eggs would lead to food poisoning and other diseases:
    The table eggs, like any other perishable food material, like milk, meat, vegetables, fruit etc contains high levels of moisture and may also contain few micro organisms especially on its shell surface. Even raw milk is not recommended practice and has to be consumed only after pasteurization or boiling. Similarly eggs have to be boiled or subjected to any heat treatment before eating. Generally salmonella and E.coli are common harmful bacteria that are noticed on egg shell surface. However, due the cage rearing of layers, increased automation and improved farm sanitation, the surface contamination of eggs has been reduced considerably. Moreover, there are more than 2000 serotypes in these in these bacteria and only very few of them are harmful to human beings. Due to many defense mechanisms the chances of food poisoning due egg consumption is only 1 in 1,600,000 (0.0000625%).Moreover, eggs are consumed only after cooking which will destroy the harmful microorganisms .With many natural defense mechanisms, egg is the only perishable food which can maintain its quality fairly well even for a period of two weeks at room temperature.

    IV.Desi eggs are more nutritious than farm eggs:
    Except for the shell colour and size, none of the egg quality traits and chemical components is influenced by breed of chicken. As far as the desi eggs are concerned, their nutritional composition is comparable with the farm eggs. The desi egg weighs only 2/3rd or 3/4th of the farm egg. Hence one desi egg supplies only 2/3rd 3/4th of the nutrients supplied by a farm egg. Desi eggs have darker yolks due the higher xanthophyll pigment content than the farm eggs but their vitamin A contents are comparable. Moreover, many traders are exploiting the ignorance of the public, by dipping eggs in tea decoction to change the shell colour to brown so as to sell them at a premium price.

    V.Raw eggs are more nutritious than cooked eggs:
    In order to tap the maximum nutritional value from eggs with least risk, the table should consumed as hard boiled and a raw should never be consumed due the presence of antinutrional factors like Avidin, Ovoinhibitor etc which interfere with the bioavailability of biotin and reduction in the protiolytic enzymes. On the other hand poaching, frying and scrambling of eggs may lead to partial loss of certain heat labial nutrients like B- complex group of vitamins and bioavailability of certain proteins.

    VI.Brown shelled eggs are more nutritious than white shelled eggs:
    The shell colour is due the pigments ooporphyrin and oocyan. The shell colour is a breed character and has nothing to do with the quality or nutritional value of the eggs. Moreover, the shell forms the inedible portion of the egg. Traders have exploited the ignorance of the consumers and are selling brown shelled eggs at a premium price.

    VII.Eggs contain high levels of cholesterol, hence consumption of eggs will increase the risk of coronary heart diseases (CHD):
    Cholesterol is essential component of every body cell. Consequently the body does not rely on the dietary intake, while as the liver manufacturers 70-80% of the body’s cholesterol. The remaining comes from dietary sources. Cholesterol functions as a structural component of every animal cell membrane. The brain and the spinal cord have high concentration of cholesterol because of the important role in the nervous system. It is needed to make many hormones, such as the male and the female sex hormones. The adrenal gland use cholesterol to make hormones that help to control sodium and potassium excretion as well as protein and glucose metabolism. Without cholesterol, vitamin D could not be synthesized and subsequently calcium and phosphorus could not be utilized. Cholesterol is needed by the liver to make bile salts that help in the proper digestion and absorption of lipids and fat soluble vitamins. The skin contains large amount of cholesterol which along with other fatty materials makes the skin highly resistant to the absorption of water and water soluble substance.


    What is relationship between dietary cholesterol and blood cholesterol levels?

    Since there a sufficient biosynthesis, dietary cholesterol plays no significant role on serum cholesterol levels. Extensive research and survey work carried out by the scientists of FAO, WHO.ICMR, MRFIT and DHSS of UK. COMA, ADA, AHA, USDA, and NAS also confirmed these findings. A joint study was conducted in USA screening 2,000 individuals having different levels of egg consumption per week. The study revealed no significant variations in the total serum cholesterol levels based on the number of eggs eaten by them.

    Among the dietary causes, excess energy consumption is the main factor responsible for elevated serum cholesterol levels. This was followed by excess saturated fat intake and least by dietary cholesterol. Out of the various factors responsible for hypercholestremia , all dietary causes put together will account for 20-25% only. Moreover, cholesterol is poorly absorbed(<40%) from intestines. The remaining is due to non-dietary causes. The non-dietary factors account for nearly 75-80% of increase in the serum cholesterol levels. Several factors are responsible for the hypercholestremia. Among them heredity plays a major role. Persons with the family history of hypercholestremia and coronary heart disease are prone for elevated serum cholesterol levels. This is followed by the age of an individual. Similarly smoking, severe emotional stress, diabetes mellitus, hypertension, hypothyroidism and other hormonal imbalances, excess testosterone levels in men, menopause in women, sedentary habits and occupations, lack of exercise, drugs like caffeine, obstructive jaundice, nephritis, left ventricular hypertrophy, obesity are some of the major factors responsible for hypercholestremia rather than dietary cholesterol levels. Therefore, any attempt to control serum cholesterol levels without attempting to reduce the total energy intake, obesity, smoking, alcoholism etc will be futile.

    Why this cholesterol phobia?
    Egg has been regarded as one of nature’s most perfect foods. It is perhaps the only food on the planet to get a 100 point rating from the World Health Organization.
    Many consumers still have great deal of anxiety about eating eggs. This anxiety originated many years ago when media sensationalized the fact that eggs contain cholesterol. Following this initial uncontested research, some simplistic logic developed. If any food containing cholesterol is eaten, a rise in blood cholesterol will lead to atherosclerosis and heart attacks. The public was immediately bombarded with unwarranted sensationalism about cholesterol in eggs. Today we know that the unwarranted anxiety about eggs is unjustified .The egg industry has never tried to hide the fact that eggs are a rich sources of cholesterol, yet because eggs do indeed contain cholesterol , they have been singled out as a food which everyone should omit from the diet. The public should realize that such blanket recommendations do not apply to everyone.

    Today consumers are more educated and health conscious than they were 20 years ago. Informed consumers can make reasonable decisions about their own health. Consumers should be realistic enough to know that some manufacturers continuously try to sell their products by sensationalism. Some companies are still using the “cholesterol phobia” in their tactics. Most people who understand the vital functions of cholesterol are not swayed or scared by such advertisements.

    In normal people, a short-term increase in the blood cholesterol may occur following a meal that contains high levels of cholesterol. Normally this cholesterol is properly metabolized and utilized by the body. Therefore, the increase in the blood cholesterol is short lived and these levels will eventually go down. The body has also has a regulatory mechanism to control the blood cholesterol levels.

    The continuous highly published association of cholesterol to CHD has scared the public and made it very difficult for consumers to accept the conclusion of the up-dated research. To keep from being confused on the issue, the consumer has to understand that a low cholesterol diet is a misnomer. Eating less cholesterol diet does not necessarily mean that the blood cholesterol levels will be lowered. Every person is different to cholesterol absorption. Some people may absorb as much as 85% from the diet, whereas others may have only 20% of dietary cholesterol absorption. Also the body size is not necessarily a good indicator of blood cholesterol.

    Who need to worry about high blood cholesterol?
    Certain people with continuously high cholesterol levels are classified as high risk individuals and should not be concerned about their total dietary cholesterol intake as well as total fat intake. Such individuals have to be put on cholesterol lowering drug therapy. However, normal individuals have a mechanism for regulating blood cholesterol.

    Intelligent eating habits in order to stay healthy require more than completely eliminating nutritious foods such as eggs, meat and milk from one’s diet. Such foods should never be thought of as poison. Some very high quality foods are being eliminated due simply to unnecessary fear. Because of what is now known about diet and CHD, there is no reason for the normal person to single eggs or other foods and eliminate them from the diet. All people should be encouraged to have their blood cholesterol level screened especially if they have parents with high blood cholesterol or other risk factors. These individuals with high levels should consider further diagnostic tests to determine their HDL: LDL ratios. The rest of us should not be as concerned about eating eggs and other animal products. However, everybody should maintain normal body weight, eat a balanced diet made of wholesome food and continue to make healthy food choices.

    By Dr. Mohammad Tufail Banday (Associate Professor, Skuast (K))

      Dr. Sheikh Adil Hamid (M.v.sc. Scholarh)


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