Cooking eggs makes them safer to eat, and it also makes some of their nutrients easier to digest.
One example of this is the protein in eggs.
Studies have shown it becomes more digestible when it's heated (3).
In fact, one study found that the human body could use 91% of the protein in cooked eggs, compared to only 51% in raw eggs (4).
This change in digestibility is thought to occur because heat causes structural changes in the egg proteins.
In raw eggs, the large protein compounds are separate from each other and curled up in complex, twisted structures.
When the proteins are cooked, heat breaks the weak bonds that hold them in shape.
The proteins then form new bonds with the other proteins around them. These new bonds in the cooked egg are easier for your body to digest.
You can see these changes occurring as the egg white and yolk change from a thick gel to rubbery and firm.
The protein in raw eggs can also interfere with the availability of the micronutrient biotin.
Eggs are a good source of biotin, which is an important nutrient used in fat and sugar metabolism. It's also known as vitamin B7, or vitamin H.
In raw eggs, a protein in the egg whites called avidin binds to biotin, making it unavailable for your body to use.
However, when eggs are cooked, the heat causes structural changes to avidin, making it less effective at binding to biotin. This makes biotin easier to absorb (5).
BOTTOM LINE:Cooking eggs makes the protein in them more digestible. It also helps make the vitamin biotin more available for your body to use.
Although cooking eggs makes some nutrients more digestible, it can damage others.
This isn't unusual. Cooking most foods will result in a reduction of some nutrients, particularly if they are cooked at high temperatures for a long period of time.
Studies have examined this phenomenon in eggs.
One study found that cooking eggs reduced their vitamin A content by around 17-20% (6).
One study found that common cooking methods, including microwaving, boiling and frying eggs, reduced the amount of certain antioxidants by 6–18% (10).
Overall, shorter cooking times (even at high temperatures) have been shown to retain more nutrients.
Research has shown that when eggs are baked for 40 minutes, they may lose up to 61% of their vitamin D, compared to up to 18% when they're fried or boiled for a shorter period of time (11).
However, even though cooking eggs reduces these nutrients, eggs are still a very rich source of vitamins and antioxidants (5).
BOTTOM LINE:Cooking eggs can reduce their vitamin and antioxidant content. However, they are still very high in nutrientsHigh-Heat Cooking Oxidizes the Cholesterol in Eggs
Egg yolks are high in cholesterol.
In fact, one large egg contains about 212 mg of cholesterol, which is 71% of the previously recommended intake of 300 mg per day (12).
There is now no recommended upper limit on daily cholesterol intake in the US.
However, when eggs are cooked at high temperatures, the cholesterol in them may become oxidized and produce compounds known as oxysterols (13, 14).
This is a concern for some people, as oxidized cholesterol and oxysterols in the blood have been linked to an increased risk of heart disease (15, 16).
Foods containing oxidized cholesterol and oxysterols are thought to contribute to the blood levels of these compounds (17).
The main dietary sources of oxidized cholesterol may be commercially fried foods such as fried chicken, fish and french fries (18).
It's also worth noting that cholesterol that is oxidized in the body is thought to be more harmful than the oxidized cholesterol that you eat (15).
Most importantly, studies haven't shown a link between eating eggs and an increased risk of heart disease in healthy people (19, 20, 21, 22, 23, 24).
BOTTOM LINE:High-heat cooking can oxidize the cholesterol in eggs. However, eating eggs has not been linked with an increased risk of heart disease in healthy people.https://www.healthline.com/nutrition/eating-healthy-eggs#section4
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