What Are Egg Whites?

Egg whites are the clear, viscous liquid that surrounds the yolk inside a whole egg. They make up roughly two-thirds of an egg’s total weight, and they contain about 90 percent water and 10 percent protein. Egg whites are one of the most concentrated sources of high-quality protein in the human diet, and they contain no fat and no cholesterol.

You will find them sold in cartons, separated from yolks, and used in everything from meringue to omelets. People eat them for the protein, for texture in cooking, and because they are a simple way to add protein without added fat.

What Are Egg Whites Made Of?

Egg white is mostly water, but the protein fraction is what makes it nutritionally interesting. A large egg white contains about 3.6 grams of protein, according to USDA nutritional data. It has almost no carbohydrates and essentially no fat.

The protein in egg white is not a single substance. It is a mixture of several different proteins. The most abundant is ovalbumin, which makes up more than half of the total protein. Others include ovotransferrin, ovomucoid, and lysozyme. These proteins serve biological functions in the developing chick, and some of them have properties that matter for cooking and for human nutrition.

Ovomucoid, for example, is the protein most often responsible for egg white allergies. Lysozyme has antimicrobial properties. Ovotransferrin binds iron. These details matter because they explain why egg white behaves the way it does when heated, whipped, or eaten.

Egg white also contains small amounts of vitamins and minerals, but the amounts are modest. Riboflavin and selenium are present in small quantities. The main nutritional reason people eat egg whites is protein, not micronutrients.

What Are Egg Whites Nutritionally Compared to Whole Eggs?

The clearest way to see the difference is to compare them directly. The following figures come from USDA nutritional data for one large egg.

The yolk carries all of the fat and cholesterol, plus most of the vitamins and minerals. That includes vitamin D, vitamin A, choline, and lutein. When you eat only the white, you get the protein and water but leave behind the fat-soluble nutrients.

This is a point worth stating plainly. Egg whites are not “better” than whole eggs in any general sense. They are different. They give you protein with fewer calories and no fat. Whole eggs give you protein plus a range of nutrients that the white does not contain.

Is Egg White Protein High Quality?

Yes. Egg white protein is considered a complete protein, meaning it contains all nine essential amino acids that the human body cannot make on its own. It is also highly digestible.

Protein quality is often measured by how well a protein supports growth and how easily it is absorbed. Egg white scores very well on these measures. Some research suggests that the protein in egg white is absorbed and used efficiently by the body, though absorption can vary depending on how the egg is cooked and what else is eaten at the same time.

One detail that is easy to miss: raw egg white is not absorbed as well as cooked egg white. Raw egg white contains a protein called avidin that binds tightly to biotin, a B vitamin. Cooking denatures avidin and reduces this binding. Habitually eating large amounts of raw egg white can interfere with biotin absorption. This is one reason raw egg white is not recommended as a regular protein source.

Do Egg Whites Raise Cholesterol?

No. Egg whites contain no cholesterol. The cholesterol in eggs is found entirely in the yolk.

This is why egg whites are sometimes recommended for people who are watching their cholesterol or their saturated fat intake. The evidence on dietary cholesterol and blood cholesterol is more nuanced than it was once thought to be. For most people, dietary cholesterol has a smaller effect on blood cholesterol than saturated fat and trans fat do. But the practical point stands: if you want egg protein without cholesterol, the white is the part that delivers it.

Anyone making decisions about cholesterol and diet should treat this as general information, not personal medical advice. Blood cholesterol is affected by many factors, and individual responses vary.

Who Should Be Careful With Egg Whites?

Egg white allergy is one of the most common food allergies in children. It is caused mainly by proteins in the white, particularly ovomucoid. Symptoms can range from mild skin reactions to serious reactions, and anyone with a known egg allergy should avoid egg whites entirely unless a doctor says otherwise.

Raw or lightly cooked egg whites carry a food safety risk. Eggs can carry Salmonella bacteria, and cooking is the main way to reduce that risk. The FDA advises cooking eggs until both the white and yolk are firm, and avoiding recipes that call for raw or runny eggs unless the eggs are pasteurized. This matters most for young children, older adults, pregnant women, and people with weakened immune systems.

People with certain medical conditions that require limiting protein intake should talk to their doctor before increasing protein from any source, including egg whites. This is not a common concern for healthy adults, but it is relevant for some people with kidney disease.

Are Egg Whites in Cartons the Same as Fresh Egg Whites?

Carton egg whites are real egg whites, but they are processed. They are typically pasteurized, which means they have been heated to kill bacteria. Pasteurization makes them safer to use without further cooking, and it is why carton egg whites are often used in recipes that call for uncooked egg white.

The pasteurization process can change how the protein behaves. Carton egg whites sometimes whip less readily than fresh ones, and some brands add thickeners or stabilizers to improve texture. Read the label if you want to know exactly what is in the carton.

Nutritionally, pasteurized carton egg whites and fresh egg whites are close. The protein content is similar. The main differences are convenience, safety, and how they perform in recipes.

How Are Egg Whites Used in Cooking?

Egg whites have functional properties that make them useful beyond their nutrition. When whipped, the proteins unfold and trap air, which is why egg whites can be beaten into foam for meringue, angel food cake, and soufflé. When heated, they set and bind ingredients together.

These same properties make egg whites a common ingredient in processed foods and in some commercial products. They are used as binders, thickeners, and clarifying agents. Egg white is sometimes used in winemaking to clarify wine, though this is a processing step rather than an ingredient in the finished drink.

For home cooks, egg whites are a way to add protein to a meal without added fat. They can be scrambled, used in omelets, added to smoothies, or folded into baked goods. The main thing to know is that they cook quickly and can become rubbery if overcooked.

Should You Choose Egg Whites or Whole Eggs?

For most healthy adults, there is no strong reason to avoid whole eggs. Whole eggs provide protein plus nutrients that the white does not contain, including choline and vitamin D. The evidence does not support the idea that whole eggs are harmful for most people.

Egg whites make sense when you want protein with fewer calories, when you are limiting saturated fat or cholesterol for a specific reason, or when a recipe calls for them. They are not a superior food. They are one part of a whole egg.

Some people eat egg whites because they believe the yolk is unhealthy. That belief is not well supported by current evidence for most people. The yolk contains most of the egg’s nutrients, and discarding it means discarding those nutrients along with the fat.