Eggs facts and health benefits

Eggs are a common food source and have been eaten by humans across the world for thousands of years. Eggs are reproductive shells laid by females of numerous species, including fish, reptiles, and, in terms of human nutrition, birds. While fish eggs are also consumed in a number of cultural dishes and national cuisines, bird eggs are the most commonly consumed variety of eggs by humans, and out of bird eggs, chicken eggs are by and large the most popular. It is an all-natural source of high quality protein and a number of other important nutrients. Apart from that it is a cost effective and versatile method to meet a variety of important nutrient needs of kids through older adults. Plus nutrition research recommends eggs can play a role in weight management, muscle strength, healthy pregnancy, brain function, eye health and more. Since eggs are considered to be one of the best sources of protein available. One medium-sized egg weighing 44 g typically consists of 5.53 g of protein.

History of Egg

People have been consuming eggs since there first started to be people, about six million years ago. Eggs have a lot of protein in them, and they don’t fight back – you can get them just by climbing to where the nest is and picking them up. By about 7000 BC, people in China and India were keeping chickens and eating their eggs, so they didn’t have to go hunting for wild bird eggs anymore.

However chicken eggs didn’t reach West Asia, Egypt, or Europe until about 800 BC, or even later, and people in southern Africa didn’t start to eat chicken eggs till about 500 AD. Before that, Europeans and West Asians kept ducks and geese for their eggs. About 300 BC, chicken farmers in both Egypt and China worked out ways to hatch chicken eggs in warm clay ovens, so that they didn’t need to have hens sit on their eggs to hatch them, and instead the hens could lay more eggs. (Did they get the idea from their beehives and honey farms?) This factory system made chicken eggs cheaper, and more people began to eat them.

Today chickens lay eggs all year round because farmers keep them inside in big barns with electric lights and air-conditioning so they can control the temperature and the amount of light.

At the beginning people ate their eggs raw, but once people began to use fire, about a million years ago, they started roasted eggs in the coals. With the invention of pottery, about 5000 BC, boiling eggs gradually became more common.

Nutritional Value

Apart from their delightful taste, egg is a good source of nutrients, vitamins and minerals. Consuming 50 gram of egg 15.3 µg of Selenium, 117 mg of Choline, 0.764 mg of Vitamin B5, 0.36 µg of Vitamin B-12, 0.194 mg of Vitamin B2,98 mg of Phosphorus, 4.74 g of Total Fat and 6.26 g of Protein. Moreover many Amino 0.083 g of Tryptophan, 0.276 g of Threonine, 0.334 g of Isoleucine, 0.541 g of Leucine, 0.454 g of Lysine, 0.189 g of Methionine and 0.136 g of Cystine are also found in 50 gram of eggs

Health benefits of Eggs

Eggs are a very good source of inexpensive, high quality protein. More than half the protein of an egg is found in the egg white along with vitamin B2 and lower amounts of fat and cholesterol than the yolk. Whites are rich sources of selenium, vitamin D, B6, B12 and minerals such as zinc, iron and copper. Listed below are some of the popular health benefits of consuming eggs

1. Help to Lose Weight

Eggs are amazingly fulfilling. They are a high protein food… but protein is by far the most fulfilling macronutrient. Eggs score high on a scale called the Satiety Index, which measures the ability of foods to induce feelings of fullness and decrease subsequent calorie intake. In one research of 30 overweight women, consuming eggs instead of bagels for breakfast increased feelings of fullness and made them automatically eat fewer calories for the next 36 hours. In another research, replacing a bagel breakfast with an egg breakfast caused substantial weight loss over a period of 8 weeks.(1), (2), (3),(4)

2. Growth and Development

The high concentration of protein, as well as other essential vitamins contained in egg means that our bodies can develop at a normal rate and get all of the necessary nutrients to grow properly and set young people on a route for lifelong health. Protein is essential for cell creation, which means that every part of our body, every organ, hair, blood vessel, and bone in some way relies on protein to exist. Also, protein is essential for repair and regrowth, so it is a lifelong necessity for us that we can acquire through eggs!(5)

3. Reduce the Risk of Stroke

For many years, eggs have been unfairly demonized. It has been claimed that because of the cholesterol in them, they must be bad for the heart.

Several research published in recent years have examined the relationship between egg consumption and the risk of heart disease. In one review of 17 studies with a total of 263,938 participants, no association was found between egg consumption and heart disease or stroke.

Several other studies have led to the same conclusion. However… some research has found that people with diabetes who eat eggs have an increased risk of heart disease. Whether the eggs are actually causing the increased risk isn’t known, because these types of studies can only show statistical association. They cannot prove that eggs caused anything. It is possible that diabetics who eat eggs are less health conscious, on average. On a low-carb diet, which is by far the best diet for diabetics, eating eggs leads to improvements in risk factors for heart disease.(6),(7), (8), (9), (10)

4. Cognitive Effects

One of the lesser known benefits of eggs is its impact on cognitive health, mainly due to the high levels of choline present. Choline is frequently grouped with B-vitamins, but in fact, it is a slightly unknown nutrient that helps to create critical neural pathways in the brain. About 90% of the population is estimated to get less choline than the body needs, but whole eggs supplies choline in large quantities!(11)

5. For Eye Health

One of the significances of aging is that eyesight tends to get worse. There are numerous nutrients that help counteract some of the degenerative processes that can affect our eyes.

Two of these are called Lutein and Zeaxanthin, powerful antioxidants that tend to build up in the retina of the eye. Research shows that consuming sufficient amounts of these nutrients can considerably decrease the risk of cataracts and macular degeneration, two very common eye disorders.

Egg yolks consist of large amounts of both Lutein and Zeaxanthin. In one controlled trial, consuming just 1.3 egg yolks per day for 4.5 weeks increased blood levels of Lutein by 28-50% and Zeaxanthin by 114-142%. Eggs are high in Vitamin A, which deserves another mention here. Vitamin A insufficiency is the most common cause of blindness in the world.(12), (13), (14), (15), (16), (17), (18)

6. Reduced Risk of Heart Disease

LDL cholesterol is normally known as the “bad” cholesterol. It is well known that having high levels of LDL is related to an increased chance of heart disease.

But what many people don’t realize is that there are subtypes of LDL that have to do with the size of the particles. There are small, dense LDL particles and then there are large LDL particles. Many researches have shown that people who have predominantly small, dense LDL particles have a higher risk of heart disease than people who have mostly large LDL particles. Even if eggs tend to mildly raise LDL cholesterol in some people, research show that the particles change from small, dense to large LDL… which is a good thing?(19), (20), (21), (22), (23), (24), (25)

7. Help to protect our bones

Eggs are among the few natural food sources of vitamin D, our sunshine vitamin. Vitamin D is important for calcium absorption and for maintaining optimum bone health. Eggs therefore play a supporting role in the prevention of osteoporosis together with dairy products, our main source of calcium.

8. Raise HDL (The “Good”) Cholesterol

HDL stands for High Density Lipoprotein. It is also known as the “good” cholesterol.

People who have higher levels of HDL normally have a lower risk of heart disease, stroke and various health problems.

Regular consumption of eggs is a wonderful way to increase HDL.

In one research, 2 eggs per day for 6 weeks increased HDL levels by 10%.(26), (27), (28), (29), (30), (31), (32),(33)

9. Promote healthy hair and nails

Hair and nails reflect several biochemical imbalances and shortages in the body. Eggs help to promote healthy hair and nails because of their high content of sulphur-containing amino acids and the wide array of vitamins and minerals.

Many people report faster growing hair after adding eggs to their diet, particularly if they were previously lacking in foods containing zinc, sulphur, vitamin B12 and vitamin A.

10. Incredibly Nutritious

Eggs are among the most nutritious foods on the planet.

Whole egg consists of all the nutrients required to turn a single cell into a baby chicken. Eggs also contain various other trace nutrients that are important for health. Really… eggs are pretty much the perfect food, they contain a little bit of almost every nutrient we need.

If you can get your hands on pastured or Omega-3 enriched eggs, then these are even better. They have more Omega-3s and are much higher in Vitamin A and E.(34), (35)

Composition of an Egg

An egg is mainly composed of several structures that all serve an important function in its construction. Besides the shell, yolk, and white, the egg contains an air cell, a chalaza, a vitelline membrane, and shell membranes. It is helpful to appreciate the function and importance of each structure to obtain knowledge that can be useful when preparing eggs.

Eggshell

Shell is actually an outer covering of the egg, which normally protects the contents from damage and contamination. The shell is composed mainly of calcium carbonate and may contain as much as 12% of the total weight of the egg.

The surface of the shell is covered with thousands of microscopic holes which makes it quite porous. A natural coating referred to as the “bloom,” helps to seal the holes, avoiding bacteria from entering. As the egg ages, the bloom is worn away, which allows moisture to slowly escape and air to enter, thus increasing the size of the air cell already present in the egg. Bacteria may also enter the egg, which may result in contamination.

The thickness and strength of the shell are determined mainly by the age of the hen and by the diet of the hen. Calcium, Vitamin D, and phosphorous are important nutrients that the hen must have in its diet in order to promote proper shell formation.

Hens produce larger eggs as they age, but the thickness of the shell decreases. This is because the same quantity of shell material is produced, but it must cover a larger volume of contents.

Air Cell

As soon as hen lays the egg, the contents of the egg begin to cool and contract. This allows air to be trapped between the two membranes beneath the shell. The trapped air produces an air cell, which forms at the large, rounded end of the egg. The size of the air cell is one of the criteria used when grading eggs. The air cell is visible as the egg passes in front of a bright light (the candling process).The smaller the air cell, the higher the grade of the egg. The size of the air cell increases as the egg ages. An egg may actually float in water if it is very old, which shows that the contents have lost moisture and the air cell has become very large.

Egg White

Egg white, also known as the albumen, surrounds the yolk with four different layers. The layers alternate from thin nearest the shell, to thick, to thin again, and finally, to thick again nearest the yolk. The individual layers are referred to as follows:

Thin Outer White: the layer nearest the shell.

Thick Outer White: moving toward the inside, the layer after the thin outer layer.

Thin Inner White: the layer after the thick outer layer, once again, moves toward the inside.

Thick Inner White: the layer next to the yolk membrane.

The egg white accounts for about two-thirds of the liquid mass of the egg and contains over half of the protein content. It has none of the egg’s cholesterol, which averages 213 milligrams and is all contained within the yolk. The egg white is not actually white in color, but opalescent. It is not until the egg is beaten or cooked that the albumen turns an opaque white.

Chalaza

Chalaza is a thick strand of the egg white that aids as an anchor. It helps to secure the yolk in the center of the thick inner white layer. Chalaza does not have to be removed before preparing the egg and it can be beaten or cooked with the rest of the egg without creating any problems. There may be some finely textured dessert recipes that may benefit from its removal, such as custards, but it isn’t a necessity.

Yolk

The yellow center portion of the egg is known as the yolk. The liquid content of the yolk is enclosed by the vitelline membrane, which help to protect the yolk from breakage. As the egg ages, the vitelline membrane loses some of its strength, so the yolk is more likely to break.

Compared with the egg white, the yolk has a greater proportion of the egg’s nutritional value. Some of the egg’s nutrients, such as zinc, vitamin A, vitamin D, and vitamin E, are fully contained within the yolk. About one-third of the liquid mass of the egg is contained within the yolk, but it contains 100% of the egg’s fat content and cholesterol and nearly half of the protein.

Healthy Egg Recipes:

Bacon and Eggs

Types of Egg

There are many types of eggs used in cooking, such as quail, duck, goose, turkey, and ostrich, but they are not used nearly as often as chicken eggs. An important point to remember is that these egg varieties are more likely to contain harmful bacteria than chicken eggs, so they should always be well cooked.

1. Guinea Fowl Egg

Guinea fowl egg has an ivory shell marked with brown; it has a more delicate taste than that of a chicken egg. 

2. Gull Egg

Gull egg, or sea gull egg, is considered a delicacy in England and Scandinavia. Since they are smaller in size, the shell is enclosed with light to dark brown blotches. It is a small egg; not surprisingly because of the fish diet of the gull, the egg has a slightly fishy flavor.

3. Goose Egg

Goose eggs are four to five times larger than chicken eggs. They have a somewhat richer flavor. The eggs can be used in any recipe calling for chicken eggs, replacing one goose egg for two chicken eggs. You can purchase eggs from free-range geese, fed certified organic feed, from LocalHarvest.org.

4. Emu Egg

Emu eggs are becoming increasingly available from breeders; they have been spotted at some Whole Foods Markets for $19.99 per egg. They have a mild yet tasty flavor. Compared to a chicken’s daily output, a good breeding pair of emus can produce just 20 to 50 eggs per breeding season. The shells are good-looking and can range from teal to dark green. The empty shells are much desired as crafts and objects d’art. The emu is the second largest bird, after the ostrich; a single emu egg is equivalent to about 10 or 12 hen’s eggs. The yolk is a paler yellow than a hen’s egg; it accounts for about 45% of the egg, compared with 34% to 35% in a hen’s egg; it contains more fat as well. The flavor is said to be stronger; while they have been a part of the Bushmen’s diet for 30,000 years, in Australia today they are served largely as curiosities. If you want to hard-cook one, it will take about 1 hour 45 minutes for a medium-sized emu egg. 

5. Ostrich Egg

Ostrich egg, along with the emu egg, is the largest egg: twenty times as large as a chicken egg. The ivory-colored shell is very thick, requiring a sharp knife to crack. Ostrich eggs are becoming more widely available, and can be found at Whole Foods Markets.

6. Partridge Egg

The egg of this small game bird is itself small. The shell is white, buff or olive in color; the egg has a mild flavor.

7. Quail Egg

Quail eggs have a similar flavor to chicken eggs, but their small size (five quail eggs equal to one large chicken egg) and pretty, spotted shell have made them popular with gourmets. The shells range in color from dark brown to blue or white. Quail eggs have a mildly gamey flavor and are popular in hors d’oeuvres, tapas and garnishes. The eggs are often hard-cooked and served as a hors d’oeuvre with sea salt, with caviar (cut in half, dab with crème fraîche and top with caviar); with baby greens or other salad treatment; on gourmet pizza; as a soup garnish or other garnish treatment.      

8. Bantam Egg

Eggs which are laid by a smaller rare breed hen, these blue-shelled eggs have a robust flavor. They are in season all year round and are best soft-boiled, scrambled or fried. These eggs also stand up well to being baked with other ingredients as they taste so strong.

9. Turkey Egg

Turkeys lay large eggs with a brown shell and a delicate flavor. The reason turkey eggs aren’t generally found for sale is economics: the average turkey produces only 100 to 120 eggs per year, compared to the average egg-laying chicken’s 300 eggs per year. Additionally, chickens begin to lay at 19 to 20 weeks of age, but turkeys don’t begin until 32 weeks. Given how much more room is needed to house a turkey (16 to 17 pounds average weight compared to 3.5 pounds for a chicken) and how much more feed is required, it takes more time and more money to produce one-third the eggs.

10. Pheasant Egg

With deep yellow yolks, these are larger than quail eggs but half the size of hens.  Beautifully olive-green or brown colored shells, they are in season from April to the end of June. Three-minute boil will give you perfectly soft eggs, with a rich flavor. Also good to use hardboiled in salads, or fried for a slightly more decadent fried-egg sandwich (try crusty bread instead of plastic white and substitute ketchup with hollandaise sauce to elevate your snack even further).

11. Rhea Egg

Another large egg (one is equivalent to ten hen’s eggs); these light and airy eggs have a strong flavor and best used in a frittata or for custards, mousse or pancakes.  They are available from March to June, they are also great scrambled or soft-boiled, but not fried.

How to select and store

Choose eggs from free-range or organically raised chickens. Eggs should always be visually inspected before purchasing. It is best to check for cracks or liquid in the box to ensure there are no broken ones. Eggs are best stored in the refrigerator where they may remain for up to one month (check the best-before-date on the box). Eggs with higher omega-3 fatty acid content are best eaten as early as possible to keep these oils fresh.

A Few Words of Warning

Eggs are obviously major sources of nutrients for the human population, there is a high level of cholesterol in them, which can be dangerous for people suffering from hypercholesterolemia and certain gene disorders should be cautious. Furthermore, some studies have shown an increase in negative effects between Type II diabetes patients and excessive egg consumption, but further research on that point still needs to be conducted.

References:

http://translation.babylon-software.com/english/egg/

https://en.wikipedia.org/wiki/Egg

http://www.eggsafety.org/types-of-eggs/

http://www.thenibble.com/reviews/main/cheese/eggs/egg-glossary.asp

http://www.dailymail.co.uk/femail/food/article-3038106/11-eggs-eating-instead-hen-s-eggs.html

http://www.recipetips.com/kitchen-tips/t–187/types-of-eggs.asp

http://www.aeb.org/farmers-and-marketers/history-of-egg-production

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