Many people who eat breakfast at restaurants order their eggs "sunny-side up," believing them to be more tender and to retain more nutrients. A sunny-side-up egg is one that is fried on only one side, leaving the yolk runny. However, a recent study in the United States has found that undercooked eggs contain harmful bacteria to the human body.
For this reason, the U.S. government has decided to put warning labels on eggshells, reminding the public that eggs contain bacteria and must be thoroughly cooked, otherwise they can cause serious illness.
Moreover, it is especially important to note that fried eggs should also be eaten as little as possible, especially sunny-side-up eggs. Not only is the yolk side prone to harboring pathogenic bacteria, but the side fried in the pan can easily burn. Burnt eggs may contain carcinogens such as benzopyrene. Furthermore, frequently eating fried eggs can easily lead to excessive fat intake, inducing high blood lipids and fatty liver. These warnings are not alarmist. First, raw eggs are easily contaminated by pathogenic bacteria. Because eggs are produced from a chicken's ovary and cloaca, which have high rates of bacterial contamination, the eggshell surface, and even the yolk, can be contaminated with bacteria. Under a microscope, one can observe that the eggshell is covered with tiny pores, with diameters dozens to hundreds of times larger than pathogenic bacteria. Therefore, eggs can be invaded by pathogens at any time. If such eggs are consumed, a person may experience food poisoning symptoms such as chills, fever, nausea, vomiting, and diarrhea.
Second, raw eggs contain two harmful substances: avidin and antitrypsin. The former hinders the contact between proteases in the human digestive tract and protein, affecting protein digestion and absorption. The latter can bind with biotin in food, forming a substance that the human body cannot absorb, which can easily lead to biotin deficiency, causing a series of symptoms such as mental fatigue, muscle soreness, and hair loss. However, once the egg is cooked, these two harmful substances are destroyed and no longer affect the human body's absorption of nutrients.
Third, the protein structure of a raw egg is tight, and a large portion of it cannot be absorbed by the human body. Only after being cooked does the protein become soft and can be digested and absorbed by the gastrointestinal tract. Studies have shown that after eating raw or undercooked eggs, the human body's digestibility is 30% to 50% lower than that of cooked eggs.
Fourth, everyone knows that raw eggs have a fishy smell that can suppress the central nervous system, reducing the secretion of digestive fluids such as saliva, gastric juice, and intestinal juice. This can lead to loss of appetite, indigestion, and even nausea and vomiting.
In comparison, boiled eggs are more nutritious than fried eggs. However, experts suggest that the optimal boiling time is generally 8 to 10 minutes. This way, harmful pathogenic bacteria can be killed, while the nutrients in the egg are relatively well preserved.