Eggs are one of the most nutritious foods available on earth. “One egg a day, keeps the doctor away” – how much truth is there in this saying? People suffering from various chronic ailments like high blood pressure, high level of uric acid/ gout, diabetes, obesity, dyslipidemia should consume egg or not? What is best mode of cooking for egg? Which part of egg, whether egg-white or yolk is more useful? Apart from using as food is there any other use of egg? Whether brown colored eggs carry more nutritional value than white colored eggs? How to identify a good egg? What is the difference between a hen’s egg and a duck’s egg? In this article I will try to answer these common questions that often arise in our mind.
History of Eggs:
When we look at the history it is known that since ancient time people have been consuming eggs of birds and approximately since 7500 BC people started keeping domestic animals and birds. In Egypt it started in 1500 BC and in Greece 800 BC. (wikipedia). It was Columbus who carried a good species of hen to America. Now a day there are more than 200 species of hen in the world. The average hen lays between 250 and 280 eggs a year and best species of hen lay more than 300. Poultry as industry started from the beginning of 19th century. In 1911 Joseph Coyle of Canada invented cartons for keeping and transporting eggs conveniently. China, America, India, Japan, Russia are the five largest egg producer countries of the world. China alone produces double of the sum of other four countries. Forty per cent of the world’s eggs are consumed in China. Worldwide, around 1.2 trillion eggs are produced every year. The average person consumes 173 eggs per year. World Egg Day is being celeb rated every 2nd Friday of October since 2012.
Structure of egg:
The egg shell comprises of calcium carbonate. It is thicker for duck compared to the chicken and hence duck’s egg can be preserved for longer duration. There are 17000 tiny pores in the egg shell through which a live egg takes respiration. There are two membranes below the egg shell. After that outer white part and inner yolk part exist. The color of the egg shell depends on the pigment deposition during its formation and varies according to species. But there is no difference in the nutritional value depending on the shell color. The egg shell may be used after consuming the inner parts for preparing various decorative items. One teaspoonful of crushed egg shell powder contains 800 to 1000 mg of elemental absorbable calcium.( mamanatural.com). This may be prepared by boiling the empty eggshells and crushing after making it dry. This calcium powder may be consumed up to one teaspoonful per day in divided doses. Calcium is good for bone health.
White part of the egg is also called the albumen. Ninety percent of it is an alkaline fluid; into it ten percent proteins are dissolved. Egg white contains no fat and almost no carbohydrate (less than 1 percent.)There are 40 varieties of protein present in egg white. It needs time to get digested and hence after eating egg we feel fullness of abdomen thus preventing us from overeating. One 50 gram egg contains 33 gram of albumen.
One 50 gram egg will have 17 gram of egg yolk. It contains fat, fat soluble vitamins (D, E, K, A) and cholesterol. Color of the yolk is due to the presence of lecithin, lutein and zeaxanthin. Lecithin is used in cosmetics. Sometimes double-yolk eggs and yolkless eggs are seen in some eggs – these are some abnormalities.
Calorie value of eggs: 20 calories comes from albumen of egg and 60 calorie from egg-yolk.
Usefulness of eggs:
Protein – Protein is needed for growth of muscle. It is an essential food in pregnancy. Amino acids present in egg increases stamina. Vitamin A is helpful for eye sight. Vitamin D is essential for the health of teeth, nail and hair. Omega 3 fatty acid is useful for lowering Triglyceride and increasing the level of beneficial HDL. Eggs are useful for person suffering from acne. Kaolin present in egg prevents stroke by maintaining normal blood circulation. One egg contains 300 microgram Kaolin. Choline, a water-soluble vitamin of B group is useful for developing body immunity by preventing Homocystine formation. Each egg contains 100 microgram Choline. It works in signaling molecules in brain therefore useful for human central nervous system. Choline give protection in Breast cancer. Trace elements present in egg are helpful in developing body immunity.
Egg yolk contains 187 mg cholesterol. Our body needs 300 mg cholesterol daily. It is utilized for synthesis of various hormones and enzymes.
How many eggs we should take daily?
Various studies reveal that 6 eggs per week is ideal. This amount of intake will not increase our blood cholesterol level. Our kidney and Liver gets stressed when we take more than two eggs at a time. Cardiac patients may take 4 eggs per week and diabetic patients may take 5 eggs per week.
Since there is no purine in egg person with high uric acid level may consume egg. Omega 3 present in egg may be helpful in hyperuricemia.
What is health procedure of taking egg?
Eggs (particularly of duck) may contain Salmonella enteritides bacteria therefore eggs must not be taken raw or half boiled. Boling destroys this bacteria. Out of various egg preparations boiling is the healthiest procedure which preserves most of the good qualities of egg. Frying the egg by trans fat like ghee degrades the quality of egg preparation.
How to identify a spoiled egg?
If the egg do not sink and remains floated in salted water, that egg is a spoiled one. In refrigerator egg remain in good condition generally for three weeks. Any egg may be spoiled in 24 hours in hot weather if not kept in fridge. Now a days in good marketing practice all egg contains expiry date and production date with batch number.
Other uses of eggs:
Eggs used for preparation of cosmetics, shamppo and for giving beautiful color to wine. In preparing Influenza vaccine egg albumen is used. In India Ahom kings used to mix raw eggs as binding material in construction of buildings. Some book binders use egg to give brightness to their binding material.
Difference between hen’s egg and duck’s egg – Larger the egg size more the vitamins and nutritional value. 100 gram duck’s egg contain 185 calorie.
Harmful effects of eggs:
Some person may have allergy to some kind of egg, In that case better to avoid that.
Since too much of anything is bad, so excessive intake of egg may be related to dyslipidemia, obesity, infertility, leg pain, indigestion etc.
Present opinion of the scientist is in favor of eggs as a nutritious food giving protection to various diseases. It does not increase the risk of heart disease rather may reduce risk of stroke. LDL cholesterol is a bad cholesterol and linked to increased risk of heart diseases. But LDL has subtypes depending on size. Small LDL particles are responsible for stroke. Eggs have tendency to change the LDL particles from smaller to large particles thus reducing risk of heart disease.(www.webmd.com).
Eggs possess anti oxidant and ant hypertensive properties beyond doubt.