Are eggs from free-range hens healthier than eggs from industrially-raised hens? It depends on how you define “healthy.” This study found that free-range eggs contain more fat and about the same amount of cholesterol. Eggs from chickens that are allowed to roam free may also have higher levels of dioxins, PCBs, pesticides, and heavy metals. By these data, free-range eggs aren’t any healthier and may in fact be less healthy.
The public perceives that the nutritional quality of eggs produced as free range is superior to that of eggs produced in cages. Therefore, this study compared the nutrient content of free-range vs. cage-produced shell eggs by examining the effects of the laboratory, production environment, and hen age.
Eggs from the range production environment had more total fat (P < 0.05), monounsaturated fat (P < 0.05), and polyunsaturated fat (P < 0.001) than eggs produced by caged hens.
Although range production did not influence the cholesterol level in the egg, there was an increase in fat levels in eggs produced on the range.
Eggs from free-range chickens have been measured to have higher levels of dioxins, PCBs, pesticides, lead, mercury, and other heavy metals than conventional eggs. This is primarily a result of environmental pollution which contaminates soil – everywhere, even in rural areas – which persists (that is, does not break down), and which bioaccumulates:
- Contamination Of Free-range Chicken Eggs With Dioxins And Dioxin-like Polychlorinated Biphenyls, Molecular Nutrition and Food Research, October 2006.
- Lead In New York City Community Garden Chicken Eggs: Influential Factors And Health Implications, Environmental Geochemistry and Health, August 2014
- Emerging Issues: Social Sustainability of Egg Production Symposium: The Impact Of Different Housing Systems On Egg Safety And Quality, Poultry Science, 2011
- Eggs From Free Range Hens May Have Higher Levels Of Environmental Pollutants, May 2013
On a positive note, arsenic-laced feed is no longer fed to commercially-raised chickens (FDA to Withdraw Approvals of Arsenic in Animal Feed), so meat and eggs from chickens should contain less arsenic. It also means that poultry manure and litter should contain less arsenic. That litter is used as fertilizer for crops, even organic crops. It is why arsenic levels in rice are so high. (Hormone use in poultry production is illegal.)