Eggs contain all the essential amino acids in the correct proportions and an excellent source of protein and other vital nutrients. They are also good source of vitamins B2, B12, D, E and folate in addition to iron. The iron and egg yolks, like the iron found in meat, is easily absorbed by the body.  Eggs are also a rich source of vitamin K. One large egg contains 25 micrograms about one-third of the daily recommended amount for women. Vitamin K is a key nutrient in blood clotting.

Eggs contains also other vitamins and minerals in smaller amounts, including vitamins B1, and B6, phosphorous and zinc. They are one of the best sources of choline, a substance involved in the transport of fat in the body. Choline is also important for the manufacture of phospholipids, which are the major structural components of cell membranes. Most of the vitamins and minerals in eggs are found in the yolk., but the white is also good source of proteins and contain little fat and no cholesterol.

 Cholesterol in eggs

Eggs are the main source of cholesterol but eggs are relatively low in calories and saturated fat. Egg white does not contain any fat. Nutritionists used to advice that eating eggs should be limited, but this advice has been revised in new studies and show that there is no link between egg consumption and risk of cardiovascular disease.

Should we limit eggs?

Cholesterol is found in large amounts only in eggs, and in offal such as liver and kidneys, but the cholesterol in these foods does not make a great contribution to blood cholesterol levels. If you have a high level of cholesterol, you have to limit eggs to three a week or if you  need to reduce  your cholesterol levels, it is more important to reduce the total amount of fat you eat, and to change the types of fat you eat. Saturated fat has more of an impact on blood cholesterol levels than eating foods high in dietary cholesterol. Eating high level of fibre food can help to reduce the amount of cholesterol that is absorbed into the bloodstream.

Eggs promote healthy hair and nails because of their high sulphur content and wide array of vitamins and minerals. Many people find their hair growing faster after adding eggs to their diet, especially if they were previously deficient in foods containing sulphur or B12.

Egg yolk color is determined by the type of feed a hen eats. A wheat-based diet will produce a pale yellow yolk, while a corn- or alfalfa-based diet yields a darker yellow yolk. The color of the yolk does not indicate egg quality, freshness, or nutritional value.

Varieties

There are many different types of eggs which come from various breeds of chicken and other poultry, and the flavour and size of the eggs laid by these birds can vary dramatically. Not all eggs are the same. When we think of eggs what usually comes to mind is a perfectly oval shaped white egg safely packed in a carton. Most of us don't think of the myriad other types of eggs that exist in the animal world. In fact, most animals on our planet lay eggs instead of having live birth. These eggs can be very varied though.

Most of us are familiar with the standard bird egg. Bird eggs come in a wide range of sizes and colors. What sets bird eggs apart from most other eggs is their hard outer shell. The award for the largest egg produced by a living species of bird belongs to the ostrich. Ostriches can produce an egg that is 6 inches long and weighs 3 pounds! The smallest bird egg is laid by the bee hummingbird.

 Some eggs are slimy, some are leathery. Some eggs are laid in nests, while others are neatly connected in strands, or glued together using foam. This lens will highlight some of the 'less thought of' varieties of eggs. Other relatively common varieties of eggs include duck eggs (larger than chicken, and with a stronger flavour), quail eggs (smaller than chicken and generally used in speciality recipes or as hors díoeuvre), and goose eggs (much larger than chicken and much stronger in flavour). These types of egg are generally specifically called for in recipes, and can be purchased from farmers markets, specialty grocers, and some butchers.

Salmonella

Some eggs may contain salmonella bacteria, which can cause serious illness. Symptoms of salmonella poisoning include abdominal pain, vomiting, and diarrhea. To minimize the risk of infection, always store your eggs in the fridge and wash your hands after handling eggs. Cook scrambled, poached, and boiled eggs until both yolk and white is firm. Some foods like home-made mayonnaise, ice-cream, and mousse are made with raw eggs and so could contain salmonella. Commercial version are made with pasteurized eggs. Pregnant women, babies and elderly people and who are unwell  should not eat raw or undercooked eggs due to the risk of salmonella poisoning.