A raw egg in a cracked shell next to whole brown eggs

Egg protein: what's in the white and why the egg is the benchmark

Updated on 23.10.2026 8 min read8 sources

Egg white is almost nothing but water and protein: raw egg white has 10.9 g of protein per 100 g, and over half of that is ovalbumin. You make homemade mayonnaise or custard, and you're left with egg whites. They end up in meringues or, more often than we'd like to admit, in the bin. Yet that's where most of the egg's protein is. In this article you'll see what's in egg white, why the egg was long the benchmark for protein, which is absorbed better, raw or cooked, and what to know about avidin and allergies.

In short

Raw egg white has 10.9 g of protein per 100 g and almost no fat. One large egg white (33 g) gives 3.6 g of protein.
The white carries over half of the egg's protein: 3.6 g of the 6.3 g in a large egg.
Over half of the protein in egg white is ovalbumin. The rest is other proteins, each with its own job.
In a small 1998 study with five people, the body absorbed 90.9% of the protein from cooked egg and 51.3% from raw egg.
The avidin in raw egg white holds on to the vitamin biotin, but loses that ability when cooked.

What's in egg white

Egg white is mostly water. According to USDA data, 100 g of raw egg white contains 87.6 g of water, 10.9 g of protein, 0.7 g of carbohydrates and only 0.17 g of fat. That comes to 52 kcal. Everything else is minerals and a few vitamins.

The protein in egg white is actually a whole group of proteins. Each of them has a job: some protect the egg from bacteria, others give it structure. Here are the main ones, based on a 2013 review in the journal Poultry Science:

Protein	Share of the protein in egg white	What it does
Ovalbumin	54%	The main protein in egg white
Ovotransferrin	12%	Binds iron so bacteria can't use it
Ovomucoid	11%	Blocks trypsin, which breaks down protein in the gut; the main allergen in egg
Ovomucin	3.5%	Gives fresh egg white its gel-like texture
Lysozyme	3.5%	Breaks down the walls of some bacteria

This built-in protection has a practical side. Raw egg white doesn't breed bacteria as easily as yolk does. That's why, in the food industry, liquid egg whites can travel to specialized drying plants, where they're made into egg white powder. We explain exactly how that works in the article “Is protein powder just chemicals?”

54%of the protein in egg white is one single protein: ovalbuminAbeyrathne et al., Poultry Science, 2013

White and yolk: how much each one brings

A large egg weighs about 50 g without the shell. Of that, 33 g is white and 17 g is yolk (USDA). The protein splits like this: 3.6 g in the white and 2.7 g in the yolk, 6.3 g in total.

The two parts are very different. The yolk is dense and rich: 100 g has 15.9 g of protein and 26.5 g of fat. The white is light: protein and water, with almost no fat. In other words, the white is almost all protein and water, and the yolk brings the fat and the creaminess.

Two halves of a hard-boiled egg on lettuce next to a slice of whole-grain bread — In one large egg, the white carries 3.6 g of protein and the yolk 2.7 g. Photo: Gül Işık / Pexels

What does this look like on the plate? Here's the math from USDA data for large eggs:

Amount	Protein
1 egg white (33 g)	3.6 g
1 whole egg (50 g)	6.3 g
Omelet with 2 eggs and 2 egg whites	19.8 g
Omelet with 3 eggs	18.8 g
10 g of egg white powder	8.1 g

Take a look at the two omelets. Two egg whites give slightly more protein than one whole egg (7.2 vs 6.3 g), without the fat from the yolk. And egg white powder is the same egg white minus the water: it has 81.1 g of protein per 100 g.

56%of the protein in an egg is in the whiteMannott et al., 2026

Why the egg was the benchmark for so long

When scientists compare proteins, they need a yardstick. For a long time, that was the egg. In a 2022 review in the journal Nutrients, Puglisi and Fernandez write that eggs are considered an ideal source of protein and serve as the reference that other proteins are measured against.

The reason lies in the scores. On what's called biological value, the egg scores 100. This measure shows how well the body uses a protein, and a high value means plenty of essential amino acids. On the newer PDCAAS score, the egg gets 1,00, the maximum, just like milk. According to the same review, the World Health Organization puts digestibility at 97% for eggs, 95% for dairy and 94% for meat.

100biological value of egg protein, among the highest in the comparison tableHoffman and Falvo, 2004

There's also a newer score, DIAAS. How these scores are calculated and why a war between animal and plant protein makes no sense, we explain in our article on animal and plant proteins. For what “essential amino acids” means, see our article on complete protein.

One more number from the Puglisi and Fernandez review: one egg provides about 500 mg of leucine. Leucine is an amino acid that research on muscle protein pays special attention to.

Raw or cooked

Remember the movie scenes where the hero drinks raw eggs from a glass? The research isn't on his side. In 1998, Evenepoel and colleagues gave five patients 25 g of egg protein, once cooked and once raw. From the cooked egg the body absorbed 90.9%, from the raw egg 51.3%.

Myth

“A raw egg is better for you than a cooked one.” In the small 1998 study, the body absorbed almost twice as much protein from cooked egg as from raw. On top of that, raw eggs can carry salmonella, which is why liquid egg white has to be pasteurized in the food industry.

Why is that? Puglisi and Fernandez explain that egg white contains substances that get in the way of protein digestion, and heat easily destroys them.

The different proteins in egg white change at different temperatures. According to the scientific review by Mannott and colleagues, ovotransferrin changes at around 61 to 65 °C, and ovalbumin at around 75 to 84 °C. That's one reason egg white sets gradually as the egg cooks.

Avidin and biotin, no need to worry

Raw egg white contains a small amount of the protein avidin, at most 0.05% of its proteins. Its job in the egg is to grab biotin (vitamin B7) so bacteria can't use it. One avidin molecule can grab up to four biotin molecules.

The same thing happens in your gut: avidin from raw egg white binds the biotin from food, and the body can't absorb it. The good news is that egg white loses this ability when it's cooked. That's what the authors of the scientific review on biotin for the 2023 Nordic Nutrition Recommendations write.

The same review says that clear biotin deficiency is rare. It has been described in people who ate raw egg whites every day for a long time, and in some medical situations. With a cooked egg, the question doesn't come up.

Egg allergy

Eggs are among the most commonly reported food allergens, especially in young children. The main allergens are in the white: ovalbumin, ovomucoid, ovotransferrin and lysozyme. The main one among them is ovomucoid.

In the EU, eggs are on the list of 14 allergens that must be labeled and highlighted in the ingredients, for example in bold. That way you'll spot them even in products where you don't expect them: in pasta, sauces or desserts.

Egg white sometimes hides in unexpected places. Lysozyme from egg white, for example, is used in the food industry as a preservative. That's why, if you have an allergy, reading labels is a habit worth keeping.

If you suspect an allergy, don't experiment. Ask your doctor.

Egg white in Bulgarian cooking

In the kitchen, the egg does more than we give it credit for. It sets, thickens, whips into foam and helps fat and water mix. That's why eggs go into the filling of banitsa (Bulgarian filo pie), into the topping on moussaka and into meringues. The review by Mannott and colleagues gives similar examples: cakes, meringues and mayonnaise.

Poached eggs on yogurt, drizzled with red chili oil — Poached eggs on yogurt, a close cousin of Panagyurishte-style eggs. Photo: Lunarly / Pexels

Panagyurishte-style eggs may be the best example: a poached egg on yogurt mixed with white cheese, topped with paprika butter. In that dish, the proteins from egg and milk meet on one plate. MEALUP does the same: egg white and milk protein meet in it. That's why it contains egg and milk and isn't suitable if you're allergic to them.

Eggs are a global food too. According to the FAO, cited in the review by Mannott and colleagues, production grew from 61.7 million metric tons in 2008 to 86.7 million metric tons in 2020. If you want to see how eggs stack up against other foods for protein, see our article on how much protein is in food.