Facts about Eggs


M. Saadat Noury
by M. Saadat Noury

Introduction: Eggs are usually defined as the oval objects with a hard shell which is produced by female birds, especially hens, and they are eaten as food. Eggs are believed to be one of the most consumed animal foods in many parts of the world. In this article a short note on the place of eggs in history, the eggs' nutritional significances, the role of eggs in providing a source of sustained energy, and the correlation between egg consumption and some diseases are studied and discussed.

A Short Note on the Place of Eggs in History: Since birds and eggs preceded man in the evolutionary chain, they have existed longer than historians. The history of Iranian Plateau and East India indicate that wild fowl were domesticated as early as 3200 BC. The long standing tradition of egg painting in areas of the world influenced by the Persian culture may be an evidence for the long history of the use of eggs in Iranian Plateau. (In the Iranian New Year called Nowruz which coincides with the first day of spring, March 20 or 21, each family member decorates a hard-boiled egg and sets them together in a bowl. A similar tradition of egg decorating exists in areas of the world where Easter is celebrated and it is accompanied with the decoration of hard-boiled eggs, usually by dyeing but often by spray-painting). Egyptian and Chinese records show that fowl were laying eggs for man in 1400 BC. Europe has had domesticated hens since 600 BC.

There is some evidences of native fowl in the Americas prior to Columbus' arrival. However, it is believed that, on his second trip in 1493, Columbus' ships carried to the New World the first of the chickens related to those now in egg production. These strains originated in Asia. Most people of the world eat the egg of the chicken, Gallus domesticas. Nearly 200 breeds and varieties of chickens have been established worldwide. Most laying hens in the North America, USA and Canada, are Single-Comb White Leghorns.

The eggs' nutritional significances: Eggs are considered as a naturally nutrient-dense food, which means they have a high proportion of nutrients to calories. One large egg has only 75 calories and provides 13 essential nutrients in varying amounts. Eggs are an excellent source of choline and a good source of the highest quality protein and riboflavin. Many of the egg's incredible nutrients are found in the egg yolk, including choline, folate, lutein, zeaxanthin and vitamin D. The yolk also includes healthy monosaturated and polyunsaturated fats and almost half of the high-quality protein found in eggs. (View the nutrient content of a large egg HERE).

Many nutritionists give credit to the eggs as the excellent source of choline because choline is an essential nutrient for nerve and brain development. Women who are pregnant or breast-feeding require increased intake of choline. Eggs also play a role in weight management, healthy pregnancy, eye health and more.

The Role of Eggs in Providing a Source of Sustained Energy: A research review published on 17 February 2009 in Nutrition Today affirms that the high-quality protein in eggs makes a valuable contribution to muscle strength, provides a source of sustained energy and promotes satiety. Researchers Donald K Layman and Nancy R Rodriguez reviewing 25 studies on protein suggest that the protein in eggs makes a valuable contribution to muscle strength, helps to satisfy hunger and provides a source of sustained energy. The same researchers suggest that because study shows eggs are rich in leucine, an essential amino acid that plays an important role in how muscles use glucose, the eggs would be a valuable food for men and women undergoing endurance training. The authors wrote that: "Given the unique complementary relationship between the essential amino acid leucine and glucose utilization by muscle, it would follow that a diet rich in the amino acid leucine would be advantageous to men and women undergoing endurance training".

The Correlation between Egg Consumption and Some Diseases: Though it is true that elevated blood cholesterol levels of Low-density lipoprotein lead to the hardening of arteries, a factor associated with Coronary Heart Disease (CHD), studies have consistently revealed that there is no definite correlation between egg intake and CHD in healthy people. Brennan Robertson in his article referred to one study from 1999 and noted that, "Eating up to one egg a day did not increase the risk for CHD when the egg consumption of 117,000 American nurses and health professionals over a 14-year period was followed up. A study published in the American Journal of Clinical Nutrition, followed 21,327 male physicians over a 20-year period and found that consuming eggs, even up to 6 a week, was not linked with a greater risk of developing cardiovascular disease. It is important to note that the same research does draw a link between egg consumption and cardiovascular disease risk for men who have diabetes. Those who ate 7 or more eggs a week had double the risk for death (most likely from heart disease) than those who consumed less than one egg a week".

 Recently in a long-term study of 57,000 American adults, Luc Djousse and his colleagues found that those who ate an egg a day were 58 percent to 77 percent more likely than non-egg-eaters to develop type 2 diabetes. The data obtained in this study was published in the February issue of Journal of Diabetes Care, and they suggest that high levels of daily egg consumption are associated with an increased risk of type 2 diabetes in men and women, and the confirmation of these findings in other populations is warranted.

Epilogue 1: It should be noted that the findings reported by Luc Djousse and his colleagues do not necessarily mean that eggs themselves put people on a path to diabetes. But they do suggest it is wise to limit the egg intake. It is also important to pay attention to the overall cholesterol intake, and not just cholesterol from eggs. Even more important, people should focus on overall health, maintaining a normal weight, exercising regularly and eating a well-balanced diet, rather than any one food or nutrient.

Epilogue 2: In the Western culture, eggs are used in many games associated with Easter, the most important annual religious feast in Christianity. Egg Throwing, aka Egg Tossing, Egg Rolling, Egg Tapping, Egg Dance, and Egg Hunt are among the various games played in Easter. There is also another form of Egg Throwing that is not a game, and it is practiced by various cultures around the world. The Egg Throwing like throwing tomato, pie, or shoe at people and particularly at a politician can be all considered as the insult or as the symbols of protest.

Manouchehr Saadat Noury, PhD


American Egg Board Website (2009): Online Notes and Articles on the Eggs.
Djousse, L. et al (2009): Egg Consumption and Risk of Type 2 Diabetes in Men and Women, J. Diabetes Care: Vol. 32, Pp. 295-300
Layman, D. K. and Rodriguez, N. R. (2009): Egg Protein as a Source of Power, Strength and Energy, Nutr Today: 44(1): Pp. 43-48.
Norton, A. (2009): Online Article on Egg Intake Linked to Diabetes Risk.
Robertson, B. (2007): Online Article on Exceptional Eggs.
Saadat Noury, M. (1970): Poultry Research Development in Iran, World's Poultry Science Journal: Vol. 26, Pp. 800-802.
Saadat Noury, M. (1976): Principles of Experimental Nutrition, ed., (in Persian), Tehran University Publications, Tehran, Iran.
Saadat Noury, M. (1982): Principles of Human Nutrition in Health and Disease (in Persian), ed., Tehran, Iran.
Saadat Noury, M. (2007): Online Article on Happy Moments in Nowruz.
Saadat Noury, M. (2008): Various Articles on Vitamins and Nutrition.
Various Sources (2009): Notes on the Eggs.
Wikipedia Encyclopedia (2009): Online Articles on the Eggs, Egg Tossing and other Games.

Read more about the Moments in the Nutritional Department on MISSING MOMENTS


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Rad Lanjani

I should also say:

by Rad Lanjani on

Thank you for sharing.

Rad Lanjani


by Rad Lanjani on

Good informative article.