Eggs are one of the best and cheapest sources of protein. A few things you may or may not have known about eggs.

1. The shell of a bird’s egg consists of calcium carbonate. The shell makes up 9-12% of the total weight of the egg and contains pores through which oxygen enters and carbon dioxide and moisture leave.

2. Egg whites are mainly composed of a protein called albumin, and also contain niacin (vitamin B3), riboflavin (vitamin B2), chlorine, magnesium, potassium, sodium and sulfur. Egg whites contain about 57% of hen’s egg protein. However, you should not eat egg whites raw – both because of possible salmonella infection and because it contains the protein avidin, which binds vitamin biotim and can cause a deficiency of this vitamin.

3. The color of the yolk is determined by the hen’s diet. The more yellow and orange plant pigments there are in the food that the hen is fed, the more vivid the color of the yolk will be.

4. Egg yolk lecithin is a natural mixture of phospholipids extracted and refined from egg yolk and is an amphiphilic molecule. According to the different types of basic alcohols, egg yolk lecithins are mainly divided into two categories: glycerol-based (glycerophospholipids) and sphingosine-based (sphingomyelin). Otherwise, lecithin is a natural emulsifier – mixture stabilizer.

5. Eggs take about 24 to 26 hours to form inside the hen. First, the egg cell develops into a yolk inside the ovary, where Salmonella bacteria can enter the egg. During ovulation, the follicle bursts and the yolk is released into a tube called the fallopian tube. On the way through the fallopian tube, the egg white settles around the yolk, and then membranes form around the egg white.

6. For years, eggs were considered unhealthy because of the high level of cholesterol found in them. In fact, it is recommended to limit the amount of eggs eaten. But this fact arose from conclusions that are now considered incorrect from early research that cholesterol from food contributed to an increase in blood cholesterol. Many people believe that cholesterol is harmful, but the truth is that it is necessary for the functioning of our body – it builds the membrane of our cells and participates in many important processes. So don’t avoid eggs.

7. The scientific name for an egg-shaped body is ovoid .

8. Not all eggs are of this shape, that is, not all eggs are like a chicken. There are also pear-shaped eggs, for example in some species that nest on cliffs. For example, minks have an unusual pointed pear-shaped egg, which prevents the egg from falling off the cliff.

9. The largest known bird egg belongs to the extinct elephant bird (family Aepyornithidae ). His balls were about the size of an American football, or about 28 centimeters long. The elephant bird itself did not fly, and was about 3 meters tall. The bird that has the largest egg and is still alive, not extinct, is, of course, the ostrich. Its egg can weigh as much as two kilograms.

10. Hummingbirds have the smallest eggs – the length of their eggs is up to 1.5 cm, and the size of the eggs depends on the type of hummingbird.

11. Not all eggs are “egg-colored” – some are yellowish and even blue. Several species of birds, including the robin, lay blue eggs. It is thought that this could be protection against UV radiation. The emu has a blue-green textured egg.

12. Birds in colder regions have darker eggs, probably to stay warm. Dark colors absorb solar radiation better.

13. Collecting wild bird eggs is prohibited by law in many countries.

14. Many wild bird eggs have patterns and spots that serve as camouflage.

15. Birds that lay eggs in tree hollows have white eggs – so the bird can recognize them. Also, these eggs don’t really need masking.

16. Often the males of some species lay on the eggs. This is, for example, the case with pigeons.

17. Although the ostrich egg is the largest, the real egg-laying hero is the kiwi bird ( Apteryx australis ), whose egg is as much as 20% of the bird’s size, in contrast to the ostrich whose egg is only about 2% of its weight.



Jelena Kalinić, MA in comparative literature and graduate biologist, science journalist and science communicator, has a WHO infodemic manager certificate and Health metrics Study design & Evidence based medicine training. Winner of the 2020 EurekaAlert (AAAS) Fellowship for Science Journalists. Short-runner, second place in the selection for European Science journalist of the year for 2022.