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Will Wister, investment fund manager, health advocate and intellectual philanthropist, explains how free range eggs are not necessarily from chickens raised on a pasture:

It’s important to distinguish between “free range eggs” and “pastured eggs”

According to the law, “free-range” doesn’t really mean much of anything. The thing that makes eggs healthy and nutrient-dense is when hens have access to the outdoors, to sunlight, to bugs. If a label says “free-range,” it guarantees none of those things.

In fact “free-range” can simply mean that the hens have “access” to the outside for as little as five minutes a day! They may not even choose to go outside, and when they do, they may simply be walking out into a concrete slab devoid of any bugs, larvae, or grass.

A similar thing can be said for the “cage-free” label. All that means is that rather than being crammed into cages stacked on top of each other, hens are cage-free. They can still be confined indoors for their entire lives, never seeing a day of sunshine.[6]

Here’s more on that distinction:

“Free range” eggs, according to the United States Department of Agriculture, must come from chickens which are offered access to the outside. Many commercial production companies provide this access in the form of a small door which is opened a few times a day; used to being confined indoors, the chickens make no move to explore the outdoors. Pastured eggs, however, come from chickens which are raised on pasture, with mobile coops to roost in at night.[8]

Pastured eggs are more nutritious.

One commercial egg has about 34 IU of vitamin D, according to the USDA[1] The numbers for pastured eggs can be 3-6 times that amount or more[1][2][3][4][7] These results are based on data from 14 farms that produce pastured eggs and then comparing that data to USDA data on standard eggs.[4] This makes sense. See Do animals absorb vitamin D from sunlight?

Of course the benefits of pastured eggs don’t stop at Vitamin D

pastured eggs containing 2/3 more vitamin A, 3 times more vitamin E, 7 times more beta carotene, 2 times more beneficial omega-3 fatty acids, 1/3 less cholesterol and 1/4 less saturated fat.[1]

Pastured eggs had 50% more folic acid and 70% more vitamin B12 than eggs from factory farm hens. (1974 – The British Journal of Nutrition)[5]

Eggs from pastured eggs are often have a different hue. They can be almost orange, reflecting higher vitamin content and other factors:

The color may vary based on the season and how many bugs or green grasses the hen eats.[6]

Beyond that pastured eggs often have larger yolks in proportion to the tolk size of the eggs, and the thick part of the egg white is often more voluminous proportionally, and thicker, while the thin part of the egg white thinner and less voluminous proportionally[6].

[1] http://www.organicconsumers.org/…
[2] http://www.motherearthnews.com/R…
[3] http://www.fullsirclefarms.com/v…
[4] http://wholehealthsource.blogspo…
[5] http://healingthewholechild.com/…
[6] http://www.foodrenegade.com/heal…
[7] http://www.inpasturesgreen.com/a…
[8] http://www.wisegeek.com/what-are…