Amino acids are often called building blocks of protein because your body uses them to make hundreds of different proteins. Proteins are crucial for cellular repair and production of new cells and also function as enzymes that catalyze reactions; receptors that bind hormones and other compounds; and carriers for components in your blood. Egg whites are a rich source of many different types of amino acids that your body needs to make proteins and support your health and well-being.
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Essential Amino Acids
Some amino acids are called essential amino acids because your body can't manufacture or store them in excess amounts, necessitating the consumption of them as a regular part of your meals. Egg white from a single large egg contains about 3.6 grams of protein that provides the essential amino acids. For example, it contains about 0.3 gram of leucine and about 0.25 gram of lysine. The same amount of egg white also contains about 0.2 gram of phenylalanine, 0.26 gram of valine and lesser but significant amounts of all the other essential amino acids.
Conditional Amino Acids
Conditional amino acids can be made by your body, but consuming these as part of food can be helpful, saving your cells the energy needed to produce them. In times of illness or stress, taking in extra amounts of these aminos can be especially beneficial. Egg whites are a good source of arginine and serine, with about 0.2 gram of each in the white of a large egg. Other conditional amino acids in egg white include glycine, tyrosine, cystine and proline, with about 0.1 gram of each in an egg white.
Other Amino Acids
A few amino acids are called non-essential because your cells can convert essential amino acids into these compounds. They are also commonly produced as your body breaks down proteins as part of its normal metabolism, a process called protein turnover. Egg whites are quite rich in several of these amino acids; the white of a large egg contains aspartic acid, glutamic acid and alanine, with 0.4, 0.5 and 0.2 gm of these non-essential amino acids, respectively.
Eggs are generally healthy, but yolks are especially high in unhealthy cholesterol, so you shouldn't consume more than four whole eggs weekly, and three or less if you have diabetes or heart disease. The American Heart Association recommends you limit your daily consumption of cholesterol to 300 milligrams and also says 200 milligrams or less is best if you have high cholesterol or heart disease. One large egg contains 184 milligrams, all in the yolk. To reduce your intake of cholesterol while keeping the amount of healthy amino acids in your diet high, choose egg whites instead of a whole egg for omelets and other breakfast specialties, and replace one or more whole eggs in recipes with egg whites.