Eggs are one of the most nutritionally complete single foods anywhere in the diet. A medium chicken egg of around 60 g provides roughly 6 g of high-quality protein, several B vitamins, vitamin D, vitamin A, selenium and a substantial dose of choline. Choline is a less-talked-about nutrient that supports liver function and the synthesis of acetylcholine in the nervous system; eggs (specifically egg yolks) are one of the few common foods that provide it in meaningful quantities.
The whole egg, the white and the yolk each have a distinct nutritional shape. The white is essentially pure protein and water, with almost no fat or micronutrients; it is the bodybuilder default for high-protein, low-calorie cooking. The yolk carries all the fat, all the fat-soluble vitamins, all the choline and all the cholesterol the egg contains, in a much smaller volume. Whole eggs deliver the package together and are how most people eat them.
The historic concern about dietary cholesterol and egg intake has eased significantly over the past decade. UK NHS guidance no longer caps daily egg consumption for healthy adults, and the British Heart Foundation recognises that eggs can fit into a balanced diet. The British Lion mark, present on the majority of UK supermarket eggs, indicates the laying flock has been vaccinated against salmonella; this is what allows current advice to permit raw and lightly cooked preparations including soft-boiled eggs, mayonnaise and mousse for healthy adults and children.
Egg labels in UK shops carry production-method codes from 0 (organic) through 1 (free-range), 2 (barn) and 3 (cage). Free-range eggs make up roughly two-thirds of the UK retail market; cage production is being phased out. Storage: eggs keep best in the fridge once you have brought them home, ideally pointy-end down to keep the yolk centred. They last around three weeks past purchase, although older eggs perform better when boiled because the slightly weaker membrane lets the shell come away cleanly.
The entries below cover the canonical forms recorded in nutrition databases: whole egg, egg white and egg yolk. Each page lists per 100 g calories, protein and fat profile.