Eggs are naturally rich in vitamins and minerals, but improper preparation and consumption can negatively affect their nutritional value.

Chicken eggs are highly nutritious foods. They contain protein, fat, carbohydrates, vitamins, minerals, enzymes, and hormones. Their nutritional composition is well balanced. The protein found in the yolk is a type of phosphoprotein with one of the most complete and high-quality amino acid profiles. Egg white protein is mainly simple protein in a soluble form. Eggs are also an excellent source of amino acids that are often lacking in other foods, such as tryptophan, methionine, cysteine, and arginine. In addition, chicken eggs provide valuable lecithin.

The main reason eggs have long been viewed with caution is their cholesterol content. However, dietary cholesterol has only a minimal impact on blood cholesterol levels. Research has shown that eggs can increase HDL ("good") cholesterol and may help reduce the risk of heart disease.

Eggs are also a rich source of choline, an essential nutrient that many people do not get enough of through their daily diet. Choline is used to build cell membranes and plays an important role in producing signaling molecules in the brain, among many other functions. Although rare, choline deficiency can cause serious health problems.

A single chicken egg contains more than 100 mg of choline. Therefore, including eggs in your daily diet can help meet the recommended choline intake.

Because of their impressive nutritional profile, eggs are often referred to as “nature’s multivitamin.” However, if eggs are prepared incorrectly, they may lose nutrients and potentially become harmful to health.

Many people believe that boiling is the best and simplest way to cook eggs. All you need to do is place eggs in a pot of water and cook them until done. However, overcooked eggs may pose certain health concerns.

According to Foodies Family, boiling eggs causes both the yolk and egg white to solidify while eliminating bacteria such as Salmonella. However, The New York Times notes that overcooked boiled eggs can develop higher levels of iron sulfide. Sulfur in the egg white reacts with iron in the yolk, forming iron sulfide and creating a greenish-gray ring around the yolk. This can affect the taste and appearance of the egg and may cause digestive discomfort in some people. To avoid unpleasant odors and preserve quality, eggs should not be overcooked.

How to Boil Eggs Properly

Place the eggs in a pot of cold water and gradually bring the water to a boil. Once boiling, reduce the heat and simmer for about 3 minutes. Then turn off the heat and let the eggs sit in the hot water for approximately 5 minutes. The ideal cooking time for fully cooked eggs is about 10–12 minutes. This allows the eggs to cook through without overcooking the yolk, making them easier to digest and absorb. Adding a little salt to the water can also help prevent the shells from cracking.

Other Egg-Related Mistakes You Should Avoid

1. Eating Only the Egg White and Discarding the Yolk

An egg is perfectly designed with two complementary parts: the yolk and the white. Eating only one part can create a nutritional imbalance and reduce the overall flavor. In reality, the cholesterol content of egg yolks is not as high as many people assume. Every 100 grams of egg yolk contains about 200 mg of cholesterol. Therefore, there is usually no need to avoid the yolk.

2. Eating Too Many Fried Eggs

Fried eggs are convenient and easy to prepare, but high-temperature frying can destroy some nutrients, especially fat-soluble vitamins.

In addition, regularly consuming eggs fried in oil at high temperatures may have negative health effects, including an increased risk of obesity and certain chronic diseases.

3. Eating Eggs That Have Been Left Overnight

Cooked eggs should not be left overnight for extended periods. The longer cooked eggs are stored, the more nutrients they lose. When stored at room temperature, spoilage and bacterial growth can occur more rapidly.

Eating spoiled eggs may increase the risk of food poisoning and potentially affect internal organs. If an egg develops an unusual smell, becomes watery, or changes color, it should be discarded. For the best nutritional value, eggs should be boiled and eaten soon after cooking.

4. Eating Too Many Eggs

Although eggs are highly nutritious, nutrition experts recommend avoiding excessive consumption. Eating more eggs than the body can effectively utilize may place extra strain on digestion. This is especially important for young children, whose digestive systems may be less able to process large amounts at once.

5. Eating Raw Eggs

Raw eggs should not be consumed, nor should they be mixed directly into hot porridge or soup without proper cooking. Instead, eggs should be thoroughly cooked to reduce the risk of bacterial contamination.

The reproductive tract of chickens naturally contains many bacteria, meaning both the inside and outside of eggs can become contaminated. One of the most concerning bacteria is Salmonella, which can cause food poisoning.

When raw eggs are consumed, the body absorbs and digests only about 40% of their nutrients. In comparison:

• Soft-boiled eggs: about 100% absorption
• Lightly fried eggs: about 98.5% absorption
• Well-done fried eggs: about 81% absorption
• Sunny-side-up eggs: about 85% absorption
• Steamed eggs: about 87.5% absorption

For this reason, moderately boiled eggs are generally considered one of the best ways to preserve important nutrients such as protein, fats, minerals, and vitamins while reducing food safety risks.