The Truth About Your Eggs

July 28, 2012— -- Eggs are quite possibly the world's perfect protein source. The six grams of protein in each egg has the highest biological value -- a measure of how well it supports your body's protein needs -- of any food, including beef. The yolks contain vitamin B12, deficiencies of which can cause attention, mood, and thinking problems.

Depending on where you're getting your eggs, though, you could be getting a lot more of stuff you don't want. First you'll get some arsenic, added to feed to promote growth in hens but linked to various forms of cancer in people, and an extra dose of antibiotics, also used to promote growth but linked to antibiotic resistance and even obesity in people. Then add a heaping helping of salmonella. A 2010 study published in the journal Veterinary Record found that the eggs from hens confined to cages, as they often are in factory farms, had 7.77-times greater odds of harboring salmonella bacteria than eggs from non-caged hens.

You wouldn't know that based on what's starting to appear on egg cartons. Labels like "natural" and "cage-free" make eggs seem like they came from down on the farm, from chickens living happy lives and eating bugs. But that's not always the case. If all you want is healthy protein, it's time to start scrutinizing egg cartons. Following are nine of the most common egg-carton claims and what they mean for your health.

Read more: The 7 Best Eggs You're Not Eating

What it means: "Cage-free is certainly not like Old McDonald's farm," explains Paul Shapiro, spokesperson for the Humane Society of the United States. Generally, it means that animals are not kept in the tiny battery cages used in most egg operations. It doesn't mean the animals live outside or that they eat a diet free of arsenic and antibiotics. It is true that cage-free operations are slightly healthier for you. Cages generate more fecal dust, are associated with more disease-carrying rodents and insects, involve many cages that are difficult to disinfect, and lead to low natural immunity in stressed-out hens.

Can you trust it? No. There's no independent third party that certifies egg producers as cage-free, so you really have to take producers at their word.

What it means: Usually these types of operations allow chickens outside of cages in barns or warehouses, but they aren't required to provide the animals any specific amount of time outside—or even exposure to sunlight indoors. Chickens can still be debeaked or forced into molting, a practice used to keep hens laying eggs for a longer period of time, usually accomplished by starving the chickens, according to the Humane Society.

Can you trust it? No. Like "cage-free," there's no independent body that certifies hens as receiving adequate access to the outdoors, and the USDA has set no standards for using the claim on egg cartons.

Read more: 10 Food Label Lies

What it means: A USDA-certified organic label means the eggs came from hens that were not enclosed in battery cages, and that must be offered access to the outdoors. But the amount and duration of outdoor access isn't well defined. Organic eggs come from hens that were fed certified-organic feed, free of things like arsenic and antibiotics, pesticides, animal byproducts, and genetically modified organisms (GMOs). Forced molting and debeaking are permitted in certified-organic production.

Can you trust it? Yes. Egg producers are subject to annual audits of their operations and must pay a fee to be certified.

***

More from Rodale.com: