Eggs are highly nutritious foods. Except ascorbic acid, eggs contain almost all the nutrients necessary for human body and are easy to digest and absorb. They are ideal natural foods. All kinds of eggs are basically the same in structure and nutrition, and are mainly rich in protein, fat, vitamins and inorganic salts.
Protein content: the whole egg contains about 13%~ 15% of protein (the egg contains about protein 10%~ 15%), and the water content of yolk is less than that of egg white, so the protein content is relatively high, about 4% higher. The protein content of salted eggs and preserved eggs changed little after processing, but the protein content of egg powder was as high as 32%~42% due to lack of water.
Protein, which we often eat in eggs, is the best protein among natural foods. Can supply a plurality of essential amino acids to human body, and the composition ratio is very suitable for human body needs, and the utilization rate is high.
Among natural foods, the amino acid composition of egg protein is the closest to that of human tissue protein, so it has the highest physiological value. For example, the physiological value of protein is 94, and the yolk is 96, which is 1.3 times that of protein, 1.6 times that of beans, 1.2 times that of fish and1.65,438+0 times that of milk.
The fat content of eggs is 1 1%~ 15%, which is mainly concentrated in the yolk, with 30% fat in the yolk and almost no fat in the egg white. The content of unsaturated fatty acids in fat is high, such as 58% in egg fat and 62% in duck egg. Because of its low melting point, fat is easily digested and absorbed by human body.
Eggs contain a certain amount of lecithin and cholesterol. Egg yolk contains lecithin and cholesterol, and the cholesterol content is extremely high, reaching 1705 mg/100 g, which is 7 times that of pig liver, 0/7 times that of fat pork, 2 1 times that of yellow croaker and 0/20 times that of milk. For this reason, eggs are often considered as the main factors leading to hyperlipidemia, coronary heart disease and atherosclerosis. Some people think that elderly people with these diseases should "fast eggs".
However, some people disagree, thinking that although egg yolk contains more cholesterol, it also contains a lot of lecithin, which has therapeutic effect on patients with cardiovascular diseases, so it does not agree with the practice of "eating eggs on an empty stomach".
Dr Margaret Flynn of Missouri State University once organized a special research group on "Eggs and Cholesterol" and conducted an experiment on 1 16 men aged 32-62 for half a year. They first asked the subjects not to eat any egg food for three months, and measured the serum cholesterol content, then each person added two eggs a day, and then measured the cholesterol content three months later. There is no obvious difference between the two results, which shows that the cholesterol content of the subjects is not affected by egg cholesterol.
Someone used egg yolk to treat atherosclerosis and achieved unexpected results. They extracted lecithin from eggs, pig liver and cream and gave it to the elderly with cardiovascular diseases for 4~6 tablespoons a day for 3 months. As a result, the patient's serum cholesterol content decreased significantly. Why is this happening?
The scientific explanation is that yolk contains a lot of cholesterol, but it is also rich in lecithin. Lecithin can make cholesterol and fat particles in the blood smaller and remain suspended, thus preventing the deposition of cholesterol and fat on the blood vessel wall.
From this point of view, "fasting eggs" is unwise. Of course, eating too many eggs is not good. First, waste high-quality protein. Second, protein decomposition products increase the burden of liver and kidney. A person who eats 1~2 eggs a day can meet the nutritional needs of the body.
Eggs are also rich in minerals. Egg yolk contains more calcium, phosphorus and iron, and most of the vitamins are concentrated in egg yolk, mainly vitamins A, D and B2.
Some people like to eat raw eggs, thinking that they can supplement the body and are easy to digest, but they are not. Raw egg white contains avidin and antitrypsin. Avidin can combine with biotin in the intestine to form compounds that are difficult to be digested and absorbed by the human body, which makes the human body lack biotin. However, antitrypsin can inhibit the activity of trypsin and hinder the digestion and absorption of protein. After the eggs are cooked, avidin and antitrypsin are destroyed, which makes the dense structure of protein loose and easy for human body to digest and absorb, so we should eat boiled eggs. But don't overheat the eggs. Overheating will cause protein to coagulate excessively, or even harden and toughen, forming lumps, which will affect appetite and its digestion and absorption.