Most egg-laying hens in the U.S. are confined in what’s known as a “battery cage.” This means that hens are kept in cages less than 80 square inches, where they are fed with a meal of corn waste and chemicals and forced to lay eggs. The hens have no room to spread their wings and will never see the sunshine. What’s worse, on the off-chance that a male chick is hatched, he will be disposed of.
Indeed, all of this is atrocious and is no way for any animal to live, this lack of sunshine also contributes to a deficiency of vitamin D in hens – as well as in humans. Most people know that a reasonable amount of sunshine is good for humans as allows the body to synthesize the necessary amount of vitamin D for calcium absorption and bone development. The same can be said of chickens as well, and the proof is in the eggs.
In a study in the journal Food Chemistry, researchers have found that the egg yolks from chickens allowed to roam outdoors contain 30 percent more vitamin D than those from chickens who are kept in battery cages. The team tested the contents of 270 eggs for sale in the U.K. and found that the eggs of caged hens produced 1.7 mcg (micrograms) of vitamin D, while free-range and organic eggs contain 2.0 mcg and 2.2 mcg, respectively. To note, the recommended daily intake of vitamin D is 10 mcg for adults, and between 7 mcg to 8.5 mcg for children.
The benefits of vitamin D are nearly countless. These include promoting calcium absorption, maintaining normal calcium and phosphate levels, promoting bone and cell growth and also reducing inflammation. Conversely, vitamin D deficiency can cause weak muscles, difficulty thinking, unexplained fatigue, bone pain and increased fractures, and soft bones. A lack of vitamin D can also cause rickets in children, as well as insulin resistance, impaired immune system functioning and an increased risk of osteoporosis.