What's In an Egg: Fact & Fiction

Egg carton labels can be pretty misleading. Here's a guideline.


Natural and farm fresh mean almost nothing. These are mostly marketing ploys to help sell the eggs.

Hormone-free - again, this means nothing since egg-laying chickens are not given hormones.

Grading. Grading is unrelated to size or quality of the egg. Grade AA means the egg is smooth and well shaped, the white is clear, the yolk is intact, and an air cell within the egg is no more than 1/8" in size.


Cages. Eggs not labeled "cage-free" come from birds enclosed in "battery cages" which are small cages about the size of a car battery that are tightly stacked together.

Cage free doesn't mean a lot, simply that the birds have open space and are not confined to cages. They are given 1 square foot of space so that thousands of birds may still be packed together in a single enclosure. They don't have access to the out-of-doors and they are in too close proximity to one another to be able to behave in a healthy way. They are standing in their own excrement and can barely move around.

Free range still is only defined as cage free. In some case these chickens might have more room, but probably not. They have "access" to the outside but there are no regulations as to just what that "outside" is. It might be only a few feet of dirt.

USDA Organic. The USDA has been trying to make it easier for mega-producers of eggs to label their eggs as organic. Some of these regulations or draft regulations include features supposedly to protect chickens from salmonella contamination from wild birds, by allowing organically raised birds to be raised in the same tight quarters as cage free birds. Whether or not chickens in the outdoor are vulnerable to such contamination is debatable.

Pasture Raised, although not regulated, is used by sustainable farmers to mean that birds are allowed to roam free and not be confined to a small space. A 2007 study 1 found that pasture-fed eggs were higher in vitamin A, E and omega-3 fatty acids, as well as lower in cholesterol. A 2010 study2 substantiated some of those finding, additionally finding that hens fed on mixed grasses produced eggs with 23% more vitamin E than the hens who fed on clover.

The numbers (per egg, conventional vs. pasture-raised):1

  • Vitamin A: 487 IU vs 791.86 IU1; (more concentrated)2
  • Vitamin E: .97mg vs 3.73mg1; (twice as much)2
  • Beta-carotene: 10mcg vs. 79.03mcg
  • Omega-3s: .22g vs .66g1; (more than twice as much)2
  • Cholesterol: 423mg vs 277mg
  • Saturated fat: 3.1g vs 2.4g.


USDA Organic. The chickens have not been fed antibiotics in food or water.

Conventional. The chickens have most likely been fed GMO chicken feed that may contain antibiotics.

Omega-3 enriched eggs are like conventional eggs except that the hens have been fed a source of omega-3, such as flax seeds. Pasture-raised hens naturally produce eggs with more than twice as much omega-3. Pasture-raised hens produce eggs with more vitamin A, E, beta-carotene and less cholesterol and saturated fat.

Vegetarian fed. Since chickens' natural food includes insects, this means that the hens have been fed only commercial feed mixes, often GMO.

About Eggs

Eggs are one of those miracles of nature. The hen can produce an egg all by herself and she produces a package perfectly suited to grow a baby chicken. The hard protective shell, made of the same materials as seashells, is porous so that both air an moisture can pass through it. There's an outer membrane which protects the egg from incursion by bacteria, but this is removed in commercially raised eggs where the membrane is scrubbed off. Another internal shell membrane also helps protect from bacteria.

The egg white, composed of water and protein is a great protein source if someone doesn't want to eat the egg yolk. It provides a cushioning protection to the yolk. Strands of protein called chalaza anchor the yolk midway between the top and bottom of the egg, suspending it in the egg white. At the round end of the egg there is an air cell which increases in size as moisture leaves the egg. This is why you can determine freshness of an egg by seeing how much it floats in water.

And then there's the yolk, composed of protein, fat, cholesterol, water, vitamins and minerals. It also contains lecithin.

The egg contains over 11 essential vitamins and minerals. While content varies between pasture and commercially raised eggs, an egg generally contains 67% of the vitamin B12 we need, 14% of vitamin A, 11% of folate, 35% of iron, and 23% of selenium.


1. Mother Earth News, 2007
2. H. D. Karsten, et al, Vitamins A, E and fatty acid composition of the eggs of caged hens and pastured hens, Renewable Agriculture and Food Systems, March 2010