Ask the Expert: Eggs

CONTRIBUTOR Megan Shanahan, RD, LD

Cracking the Code

You want to know: Between grocery store refrigerators and farmers markets, egg choices are a dime a dozen: grain fed, free range, cageless, farm fresh, white, brown, blue, even purple. Is this just creative clucking by marketing experts, or is there a nutritional pecking order to these distinctions?

THE DIETITIAN SAYS: A chicken’s breed dictates egg color, but its diet and habitat determine the nutrient profile of eggs. Hens raised primarily on grains deliver eggs with pale yolks, but a marigold boost in the feed results in dark yellow yolks packed with beta-carotene. Those given algae, flaxseed or fish oil lay eggs with a higher omega 3 content. And hens that enjoy sun exposure produce eggs with more vitamin D. The language on most cartons explains how the contents were farmed.

Let’s explore the options:

Pasture raised: This term isn’t regulated by the USDA, but for eggs to be “certified humane,” the hens must be offered adequate space to roam outside plus barn cover.

Free range: USDA-regulated language, this indicates hens have unlimited outdoor access during their production cycle (though they may not be outside all of the time).

Cage free: This USDA phrase simply means the hens do not live in cages. There are no set parameters for space size or outdoor access; typically, these hens live in a barn.

Organic: Also monitored by the USDA, this term points to a diet free of animal by-products, pesticides, synthetic fertilizers, chemicals and genetically modified ingredients. Hens aren’t given any hormones or drugs to influence egg production and only receive antibiotics for infection or illness. Organic eggs must be from hens in cage-free environments.

Conventional: This broadly refers to supermarket eggs that do not qualify to be labeled as any of the above. Hens may be given hormones or antibiotics and usually eat a grain-based diet, sometimes supplemented with vitamins. Without specific habitat standards, hens likely live in cages or a hen house with little space or outdoor access.

The takeaway: A complete protein source, eggs register 60 to 70 calories; 6g protein; vitamins B, D, E and A; minerals such as iron, phosphorus and selenium; and choline, an important nutrient for nerve and liver function as well as brain development. But which carton is best for your nest? Pasture-raised and free-range eggs likely contain a higher vitamin D and carotenoid content to protect against cellular damage and eye conditions. And though pricey, organic ensures you aren’t exposed to antibiotics, synthetic hormones or other additives.

While eggs remain a hot research topic for their potential cardiovascular impact, the dietitian assures that, in moderation, they can be part of a healthy, well-balanced diet.