Eggs are one of nature's most perfectly balanced foods, containing all the protein, vitamins (except vitamin C) and minerals essential for good health.

Today's large egg contains only a moderate amount of fat, with about 5 grams in only the egg yolk, (1.5 grams saturated), 213 mg of cholesterol and 75 calories. Eggs can easily fit into your daily fat limit.

Calories : 80
Protein : 6.3 grams
Carbohydrates : 0.6 grams
Total Fat : 5.0 grams
- monounsaturated fat : 2.0 grams
- polyunsaturated fat : 0.7 grams
- saturated fat : 1.5 grams
Cholesterol : 213 milligrams
Sodium : 063 milligrams

Eggs have a high nutrient density because they provide significant amounts of vitamins and minerals yet contain only 71 calories. They are an excellent source of high quality protein (i.e. they contain all the essential amino acids) as well as many B vitamins. The nutritional value of an egg is divided between the egg white and the egg yolk.

The white contains more than half the egg's total protein, niacin, riboflavin, chlorine, magnesium, potassium, sodium, and sulfur and all the egg's zinc.

The yolk contains all of the fat in the egg and a little less than half of the protein. It also contains the fat-soluble vitamins A, D, and E. Egg yolks are one of the few foods naturally containing vitamin D. The yolk also provides vitamin B 12 and folic acid, and the minerals iron, calcium, copper and phosphorus.

The yolk contains approximately 190 mg of cholesterol and 5 grams of fat, less than a third of which is saturated fat. In the 1980's science focused on the amount of cholesterol in eggs, however recent nutrition information indicates that it is more important to focus on reducing the intake of total fat and saturated fat rather than cholesterol. This is good news for eggs. It is not necessary to limit egg or egg yolk consumption unless recommended by your physician.

While each egg white is fat and cholesterol free, yolks contain 213 milligrams of cholesterol (approximately 22% less cholesterol than previously thought) and 5 grams of total fat. Only 1.5 grams of the yolk's fat is saturated, the kind of fat that is most likely to increase blood cholesterol levels. In fact, compared with dietary cholesterol, saturated fat exerts a four times stronger influence on blood choles- terollevels. Just published research actually saw an increase in the HDL or the "good" cholesterol levels of subjects who added an egg each day to their diet [Farrel et al. 1998. Am J Clin Nutr. 68: 538-544.].

Biological Value

Eggs have been considered the standard against which all other protein foods are measured because their protein composition is so ideal.

Eggs are considered a complete protein because they contain all nine essential amino acids, or the building blocks of protein.

One large egg contains 6.3 grams of protein. The protein is almost equally split between the egg white and the egg yolk. The white contains 3.5 grams of protein while the yolk contains 2.8 grams. The protein in an egg contains all the essential amino acids used for growth and development.

Based on the essential amino acids it provides, egg protein is second only to mother's milk for human nutrition. Essential amino acids must be provided by the food we eat because our body cannot produce them. While providing 6.25 grams of the highest quality protein, each egg contains 10 percent of the USRDA.

Muscles, organs, skin, hair as well as antibodies, enzymes, transport molecules and hormones are all made from protein. Each protein has a certain number and sequence of amino acids. Nine amino acids cannot be made by the body. These nine are known as essential amino acids and you must get them from the foods you eat.

Foods that contain all nine essential amino acids are called complete protein foods. The nine essential amino acids are :

  1. Valine
  2. Leucine
  3. Isoleucine
  4. Threonine
  5. Histidine
  6. Tryptophan
  7. Phenylalanine
  8. Methionine
  9. Lysine
The remaining acids if not supplied in the diet is produced mostly from the essential amino acids.

Scientists frequently use eggs as a standard for measuring the protein quality of other foods. Protein quality is expressed as biological value, which measures the rate of efficiency that protein is used for growth. At 93.7%, eggs score higher than any other food. On a scale with 100 representing top efficiency, following are the biological values of proteins in several foods.

Whole egg : 93.7
Milk : 84.5
Fish : 76.0
Beef : 74.3
Soybeans : 72.8
Polished rice : 64.0
Wheat, whole : 64.0
Corn : 60.0
Beans, dry : 58.0