Protein
Protein is one of the three macronutrients, along with fat and carbohydrate, and contains 17 kJ per g. Proteins consist of a long chain composed of 20 different amino acids. Out of these 20, nine of them are classified as essential. An essential amino acid is one that the body cannot produce itself, and thus we must consume it through our diet. The egg contains all nine; phenylalanine, histidine, isoleucine, leucine, lysine, methionine, threonine, tryptophan and valine. It is the order of amino acids that determines which protein it is. There are loads of proteins in the body and they each have a function. Some proteins are used to form new tissue and maintain muscle. Others act in the cell's processes, or act as enzymes and hormones.
The protein in the egg has a high quality. This is due to the protein’s composition of amino acid, which is very similar to the distribution of amino acids needed by children and adults. In addition, the uptake percentage of protein from eggs is 97%, making the egg an ideal protein source with high bioavailability. In comparison, 91% of protein from meat and fish is absorbed, while only 78% protein from beans is absorbed.
Eggs contain approximately 12.5 g protein per 100 g, corresponding to between 6-8 g protein per egg depending on size. Both the egg yolk and the egg white contribute with protein - in fact the yolk contains 1.5 times as much protein per 100 g, as the white. The high amount of protein makes eggs saturating.
Of the egg's approximately 80 kcal protein contributes with 36% of the energy. Therefore, the egg can be labeled with the EU approved nutrition claim, "High protein content", which requires that at least 20% of the energy content is derived from protein.
Eggs are an eco-friendly source of animal protein. The production of eggs emits less CO2 per kilo produce than the production of beef, pork and chicken, as well as fish, seafood and cheese.