When is an Egg Just an Egg

Nutritional difference in how eggs are produced questioned

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) Most people believe hens that are able to roam freely make better, nutritious eggs than caged hens. The truth about this theory may be surprising to some.

Researchers put the common perception to the test to see if the production difference in eggs added or negated to nutritional value. During this test they also found another interesting fact that surprised the United States Department of Agriculture (USDA).

"Any egg is equally nutritious with vitamins, minerals and protein."

Kenneth E. Anderson, Ph.D., a professor in the Department of Poultry Science at North Carolina State University, and team found no nutritional difference in eggs produced from free range or caged chickens.

No matter where the egg was produced, it was still nutritious, Anderson says. Surprisingly though, both eggs produced by free range and caged had lower levels of cholesterol than was previously believed by the USDA, he adds.

This study has led the USDA to lower their cholesterol guidelines for eggs from 213 milligrams of cholesterol to 185 milligrams of cholesterol per egg, according to Anderson.

The study was conducted in North Carolina using over 400 Hy-Line Brown young hens. The young hens were raised according to the North Carolina Layer Performance and Management Test. Hens were fed the same whether they were free-ranged or caged.

Eggs were collected at 50, 62 and 74 weeks of age during the productive life of the flock. They were then sent to four different laboratories that are commonly used for egg nutrient analysis.

Vitamins A and E and cholesterol levels were similar in both cage and range produced eggs. Eggs produced in the range had slightly higher beta-carotene, which could explain the darker color of the yolks.

Free range produced eggs also had slightly higher levels of total fat compared to cage-produced eggs.

Overall, the results show that there is no advantage when it comes to how eggs are produced, Anderson says.

The research is published in Poultry Science.

Reviewed by: 
Review Date: 
August 30, 2011
Last Updated:
September 3, 2011