Eggs have long been recognized as a source of high-quality protein. The World Health Organization (WHO) and other public health authorities actually use eggs as their reference standard for evaluating the protein quality in all other foods. Egg protein is usually referred to as “HBV” protein, meaning protein with High Biological Value. Since eggs are used as the reference standard for food protein, they score 100% on the HBV chart. The high quality of egg protein is based on the mixture of amino acids it contains. (Amino acids are the building blocks for making proteins.) Eggs provide a complete range of amino acids, including branched chain amino acids (leucine, isoleucine, valine), sulfur-containing amino acids (methionine, cysteine), lysine, tryptophan, and all other essential amino acids. Their protein is sometimes referred to as a “complete protein” for this reason.

All B vitamins are found in eggs, including vitamins B1, B2, B3, B5, B6, B12, choline, biotin, and folic acid. Choline is a standout among these B vitamins. In fact, eggs rank higher in choline than any of our other WHFoods. In the U.S., an average diet provides about 300 milligrams of choline per day – less than the recommended amount for an adult woman (425 milligrams) or an adult man (550 milligrams). Since one egg provides over 100 milligrams of choline and only 75-80 calories, it provides far more choline for far less calories than most other choline-rich foods.

The mineral content of eggs also deserves special mention here–not because eggs are a rich source of most minerals but because they are a rich source of certain minerals that can sometimes be difficult to obtain from other foods. Eggs are a very good source of both selenium and iodine. While many fish, shellfish, and mushrooms can be rich sources of selenium, persons who avoid these foods may sometimes have difficulty getting an adequate amount of this important antioxidant mineral from food. For persons who do not use iodized salt in recipes or at the table and who do not consume either yogurt or cow’s milk, this mineral can also sometimes be challenging to obtain from food.

The nutrients found in an egg are distributed fairly evenly between the yolk and the white. This distribution of nutrients is a common characteristic of whole, natural foods and it is one of the reasons that we recommend consumption of whole eggs (except, of course, when only the yolk or the white is called for in a recipe). The chart below explains what approximate percent of the total nutrient amount is found in the yolk and the white of an egg. You will notice that the first four nutrient groupings are those that are found predominately in the egg white, while those that follow are found predominately in the egg yolk (all except for the last nutrient, selenium, which is divided fairly evenly between the egg white and yolk).

Omega-3 Support

In recent years, there has been a food marketplace trend of greater availability of eggs that are unusually rich in omega-3 fats. These eggs get their high levels of omega-3s through the addition of omega-3 oils to the hen’s feed. Oils added to the hen’s diet as a way of increasing omega-3s include menhaden oil, krill oil, flaxseed oil, and algae oil. The supplementation of the hen’s diet with these oils usually produces as much as 250 milligrams of omega-3s per egg yolk.

What many consumers do not know is that virtually all egg yolks contain omega-3 fats and that by providing hens with a natural, pasture-based diet their omega-3 levels can be naturally increased. Pasture feeding can provide the hen with clover and alfalfa, two examples of legumes that are rich in omega-3s; in fact, pasture feeding can double the amount of omega-3s in an egg yolk. Omega-3s are far too low in the average U.S. diet, and eggs from pasture-raised chickens can provide significant amounts of these anti-inflammatory fats.