The Nutritional Value of One Hard-Boiled Egg

Nutritional value
Chicken egg, whole, hard-boiledNutritional value per 100 g (3.5 oz)
Energy 150 kcal 650 kJ
Carbohydrates
1.12 g
Fat
10.6 g
Protein
12.6 g
Water
75 g
Vitamin A equiv. 140 μg
16%
Thiamine (Vit. B1) 0.066 mg
5%
Riboflavin (Vit. B2) 0.5 mg
33%
Pantothenic acid (B5) 1.4 mg
28%
Folate (Vit. B9) 44 μg
11%
Calcium 50 mg
5%
Iron 1.2 mg
10%
Magnesium 10 mg
3%
Phosphorus 172 mg
25%
Potassium 126 mg
3%
Zinc 1.0 mg
10%
Choline
225 mg
Cholesterol
424 mg
For edible portion only. Refuse: 12% (Shell)Percentages are relative to USrecommendations for adults.Source: USDA Nutrient database

Eggs add protein to one's diet, as well as various other nutrients.
Chicken eggs are the most commonly eaten eggs.

They supply all essential amino acids for humans,[17] and provide several vitamins and minerals, including vitamin A, riboflavin, folic acid, vitamin B6, vitamin B12, choline, iron, calcium, phosphorus and potassium.

They are also an inexpensive single-food source of protein.

All of the egg's vitamin A, D and E is in the egg yolk. The egg is one of the few foods which naturally contain Vitamin D.

A large egg yolk contains approximately 60 Calories (250 kilojoules); the egg white contains about 15 Calories (60 kilojoules). A large yolk contains more than two-thirds of the recommended daily intake of 300 mg of cholesterol (although one study indicates that the human body may not absorb much cholesterol from eggs[18]).

The yolk makes up about 33% of the liquid weight of the egg. It contains all of the fat in the egg and slightly less than half of the protein and much of the nutrients. It also contains all of the choline, and one yolk contains approximately half of the recommended daily intake. Choline is an important nutrient for development of the brain, and is said to be important for pregnant and nursing women to ensure healthy fetal brain development.[19]

Recently, chicken eggs that are especially high in Omega 3 fatty acids have come on the market. These eggs are made by feeding laying hens a diet containing polyunsaturated fats and kelp meal. Nutrition information on the packaging is different for each of the brands.

Health issues of eating chicken eggs

Cholesterol and fat
More than half the calories found in eggs come from the fat in the yolk; a 100 gram chicken egg contains approximately 10 grams of fat. People on a low-cholesterol diet may need to reduce egg consumption, although only 27% of the fat in egg is saturated fat (Palmitic,Stearic and Myristic acids) that contains LDL cholesterol. The egg white consists primarily of water (87%) and protein (13%) and contains no cholesterol and little, if any, fat.

There is debate over whether egg yolk presents a health risk. Some research suggests dietary cholesterol increases the ratio of total to HDL cholesterol and, therefore, adversely affects the body's cholesterol profile;[20] whereas other studies show that moderate consumption of eggs, up to two per day, does not appear to increase heart disease risk in healthy individuals.[21] Harold McGee argues that the cholesterol in the yolk is not what causes a problem, because fat (particularly saturated) is much more likely to raise cholesterol levels than the actual consumption of cholesterol.[14] A 2007 study of nearly 10,000 adults demonstrated no correlation between moderate (6 per week) egg consumption and cardiovascular disease or strokes except in the sub-population of diabetic patients which presented an increased risk of coronary heart disease.[22] Other research supports the idea that a high egg intake increases cardiovascular risk in diabetic patients.[23] However, some "no correlation" findings have come under attack by independent observers for flawed methodology and financial ties to the egg industry.[24]

Type 2 diabetes
Consumption of eggs has been linked to an increased risk of Type 2 diabetes in both men and women. A 2008 study using data on over 50,000 individuals collected by the Physicians' Health Study I (1982-2007) and the Women's Health Study (1992-2007) determined that the “data suggests that high levels of egg consumption (daily) are associated with an increased risk of type 2 diabetes.”[25]

Contamination
A health issue associated with eggs is contamination by pathogenic bacteria like Salmonella enteritidis. Contamination of eggs exiting a female bird via the cloaca may also occur with other members of the Salmonella group, so care must be taken to avoid the egg shell becoming contaminated with fecal matter. In commercial practice, eggs are quickly washed with a sanitizing solution within minutes of being laid. The risk of infection from raw or undercooked eggs is dependent in part upon the sanitary conditions under which the hens are kept.
Health experts advise people to refrigerate eggs, use them within two weeks, cook them thoroughly, and never consume raw eggs.[26] As with meat, containers and surfaces that have been used to process raw eggs should not come in contact with ready-to-eat food.

A study by the U.S. Department of Agriculture in 2002 (Risk Analysis April 2002 22(2):203-18) suggests the problem is not as prevalent as once thought. It showed that of the 69 billion eggs produced annually only 2.3 million are contaminated with salmonella - equivalent to just one in every 30,000 eggs - thus showing that salmonella infection is quite rarely induced by eggs. However, this has not been the case in other countries where Salmonella enteritidis and Salmonella typhimurium infections due to egg consumptions are major concerns [27], [28], [29].
Egg shells act as hermetic seals which guard against bacteria entering, but this seal can be broken through improper handling or if laid by unhealthy chickens. Most forms of contamination enter through such weaknesses in the shell.

Food allergy
One of the most common food allergies in infants is eggs.[30] Infants usually have the opportunity to grow out of this allergy during childhood, if exposure is minimized.[citation needed] Generally, physicians will recommend feeding only the yolks to infants because of the higher risk of allergic reaction to the egg white.[citation needed]
The egg allergy is prevalent enough in the United States that food labeling practices now include eggs, egg products and the processing of foods on equipment that also process foods containing eggs in a special allergen alert section of the ingredients on the labels.

Chicken egg grading
The US Department of Agriculture grade eggs by the interior quality of the egg and the appearance and condition of the egg shell. Eggs of any quality grade may differ in weight (size).
U.S. Grade AA eggs have whites that are thick and firm; yolks that are high, round, and practically free from defects; and clean, unbroken shells. Grade AA and Grade A eggs are best for frying and poaching where appearance is important.
U.S. Grade A eggs have characteristics of Grade AA eggs except that the whites are "reasonably" firm. This is the quality most often sold in stores.
U.S. Grade B eggs have whites that may be thinner and yolks that may be wider and flatter than eggs of higher grades. The shells must be unbroken, but may show slight stains. This quality is seldom found in retail stores because they are usually used to make liquid, frozen, and dried egg products, as well as other egg-containing products.

Chicken egg sizes

Medium White Eggs in Carton
Chicken eggs are graded by size, for the purpose of sales. The United States Department of Agriculture sizing is based by weight per dozen. The most common US size of chicken egg is 'Large' and is the egg size commonly referred to for recipes. The following egg masses have been calculated on the basis of the USDA sizing:
Modern Sizes (USA)
Size
Mass per egg
Cooking Yield (Volume)[1]
Jumbo
Greater than 2.5 oz. or 71g
Very Large or Extra Large (XL)
Greater than 2.25 oz. or 64g
56 mL (4 tbsp)
Large (L)
Greater than 2 oz. or 57g
46 mL (3.25 tbsp)
Medium (M)
Greater than 1.75 oz. or 50g
43 mL (3 tbsp)
Small (S)
Greater than 1.5 oz. or 43g
Peewee
Greater than 1.25 oz. or 35g