… 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 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).
Chicken eggs are by far the most common type of egg consumed in the U.S., and the breeding of chickens for egg production has resulted in breeds that can lay 200-300 eggs per hen per year. Some of the more popular egg-laying breeds include White Leghorns, Rhode Island Reds, Buff Orpingtons, Golden Coments, Red Sex Links, Isa Browns, Australorps, Black Star, Red Star, Light Sussex, and Plymouth Rock. All of these breeds belong to the same genus, species, and subspecies of animal, namely, Gallus gallus domesticus. You may also hear chickens being referred to as “Junglefowl,” which is a common name for all animals belonging to the Gallus genus.
The composition of an egg is usually described as having two basic parts: the white and the yolk. The white is approximately 87% water and 13% protein, and contains both vitamins and minerals. The yolk is about 50% water, 33% fat, and 17% protein; like the white, it also contains both vitamins and minerals.
Egg grading standards are based on the clearness, firmness, and thickness of the white, the presence or absence of defects in the yolk (like blood spots or meat spots), the size of the air cell inside of the shell (the smaller this air space, the higher quality the egg), and the cleanness of the shell, including the absence of any slight breakage. Eggs that score highest on these qualities are graded “AA.” Fairly close in quality are “A” eggs. The shelf life of an egg is related to its grade, and a fresh AA egg will have a longer shelf life than a fresh A egg.
Today, egg production in the U.S. has reached a level of 762 billion eggs per year. About 70% of these eggs are sold and purchased in whole form, and about 30% are removed from shells at “breaker plants” across the country and converted into egg products, including both liquid and dried yolks and whites. Iowa, Ohio, Pennsylvania, Indiana, and California are the country’s top five egg-producing states. On a global basis, the U.S. is the largest egg-producing country in the world, followed by Mexico and Brazil. However, small numbers of eggs are produced in most countries worldwide, and out of the world’s total (63.7 million tons of hen’s eggs), only 20% (12.8 million tons) are produced in all North American, Central American, and South American countries combined.
If you do decide to consider the addition of eggs to your meal plan, we encourage you to take a close look at your overall diet. Could it use more protein? If so, eggs might make sense. Does it already have plenty of fibre? If not, it might make more sense to add a fibre-containing food rather than eggs. We are confident that in many diets, pasture-raised eggs can provide key nutrient benefits and lower your disease risk, despite some of the confusion that we have come across in the food science research.
By Bismark Adika/MJA-Ghana