Are eggs the best source of protein? Nutritional comparison of white eggs and yellow eggs
Eggs are a cheap and excellent source of dietary protein. The term "excellent" refers to the proportion of essential amino acids that make up egg protein, which is quite close to the proportion of essential amino acids in human protein structure. Since the human body cannot synthesize these amino acids on its own, they must be supplied through food, and egg protein is one of the best choices.
In addition to the protein that is abundant in both the egg white and the yolk, the egg white is also a rich source of vitamin B2, B3 and the minerals potassium, magnesium and copper, while the yolk contains more fat (so it provides more calories than the egg white) and essential fatty acids, and is also a source of cholesterol, the fat-soluble vitamins A, d and è and lecithin. Moreover, the yolk is also rich in the water-soluble vitamins B1, B2, B3, B6, B12, folic acid and choline, as well as the minerals potassium, calcium, magnesium, iron, zinc and phosphorus.
The types of eggs sold on the market include: white-shell eggs, yellow-shell eggs, free-range eggs, first-lay eggs, and specially nutrient-fortified eggs (such as high linoleic acid, high linolenic acid, high HDA, high vitamin E, high vitamins A and E). In addition, there are fresh eggs that emphasize being organic or naturally pasture-raised. From the perspective of nutritional value, apart from eggs whose content of specific nutrients such as certain fatty acids or fat-soluble vitamins has been increased through feed, the nutrient content of eggs under various names, especially their protein and fat content, is actually much the same.
The nutritional value of eggs for the human body
According to the analysis of the nutritional composition of eggs on the market in the "Food Nutrient Composition Database (New Edition)" of the Food and Drug Administration, Ministry of Health and Welfare, one egg, after removing the shell and mixing the yolk and white, has an average net weight of about 55 grams. Analysis of the mixed white and yolk shows that every 100 grams on average contains 75 grams of water and provides 135 kcal of calories, 1.3 grams of carbohydrates (mainly in the yolk), 8.6 grams of fat (mainly in the yolk; of which saturated fat is close to 1/3 of the total fat content) and 12.5 grams of protein (contained in both the white and the yolk).
The cholesterol in eggs exists only in the yolk. Every 100 grams of yolk contains on average 1177 milligrams of cholesterol, and one yolk weighs about 17 grams on average, meaning it provides 200 milligrams of cholesterol. This is equivalent to 2/3 of the recommended daily cholesterol intake.
In particular, eggs contain almost all vitamins. For the vitamins provided by every 100 grams of eggs, ranked by the percentage they represent of the recommended daily intake, the order is: choline (70%), vitamin B12 (42%) and riboflavin (42%), vitamin A (28%) and pantothenic acid (28%), vitamin d (15%), folic acid (13%), vitamin E (9%), vitamin B6 (8%), vitamin B1 (7%), niacin (1.5%). In addition, eggs also contain important mineral nutrients. For the minerals provided by every 100 grams of eggs, ranked by the percentage they represent of the recommended daily intake, the order is: phosphorus (26%), zinc (9%), calcium (5.5%), potassium (4%), magnesium (3.5%). As mentioned above, these nutrients are not evenly distributed.
between the egg white and the yolk; rather, the yolk and the white each have their own nutritional value. Therefore, if some consumers, out of concern about the calories and cholesterol in the yolk, discard the yolk and eat only the white, although they can still obtain most of the high-quality protein in the egg, they will also exclude the lecithin and most of the vitamins and minerals provided by the egg.
