A whole egg is a very nutritious package of food. An average sized hen’s egg contains around six grams of a high quality, complete protein. A “complete” protein contains all the amino acids that our body is unable to make, and these amino acids are all present in significant amounts. Most – but not all – of an egg’s protein is in the egg white.
Eggs also contain many other valuable nutrients, including the fat-soluble vitamins A, D and E and the water-soluble vitamins B2 (riboflavin), B12 and folate. Eggs contain a selection of beneficial minerals, including zinc, iron, selenium and calcium. In addition, egg yolks contain two orange pigments, lutein and zeaxanthin, in a form that is easily absorbable by the body. Lutein and zeaxanthin are present in the retina of our eyes. Research suggests that diets rich in these nutrients slow macular degeneration and cataract development. The macula is an area of the retina (the light-sensitive layer at the back of the eyeball) which provides highly detailed vision. A cataract is a clouding of the lens of the eye, which hinders light entrance into the eyeball.
Eggs contain choline and lecithin, substances that are important parts of the cell membranes around our cells. In addition, choline forms part of acetylcholine molecules. Acetylcholine is a neurotransmitter – a chemical that transmits a nerve impulse from one nerve cell to another.
Yes, egg yolks do contain a large amount of cholesterol. A medium-sized egg contains about 185 mg of cholesterol and a large egg contains around 213 mg. Cholesterol is only found in food that comes from animal sources. It’s especially abundant in liver, kidney, shrimp and eggs. However, scientists have found that a person’s intake of saturated fats and hydrogenated fats has a far greater effect on his or her blood cholesterol level than eating food that contains cholesterol.
An egg contains only a small amount of saturated fat – 1.5 grams out of 5 grams of fat in total. Various research studies have shown that eggs in the diet have no or only a very small effect on blood cholesterol level. The current thinking amongst most nutritionists is that eggs are a valuable addition to the diet. The American Heart Association does recommend that people eat less than 300 mg of cholesterol per day. If a person follows this recommendation it would still be possible to eat an egg a day (if other cholesterol - containing foods are limited) and meet the Heart Association cholesterol guidelines.
There is at least one group of people who may be advised by doctors to restrict the intake of dietary cholesterol. Avoiding or strictly limiting eggs and other foods containing cholesterol is sometimes recommended for people who suffer from familial hypercholesterolemia – an inherited condition in which the level of cholesterol in the blood is abnormally high. People with heart disease or diabetes may also be advised to limit their intake of cholesterol.