It’s common to see eggs and chicken breasts advertised as 100% vegetarian-fed. At first glance, this might seem like a healthy choice. It’s easy to assume that meat and eggs from vegetarian-fed chickens are more nutritious than conventionally raised chickens.
There is one problem, chickens are not vegetarians. Chickens do not naturally seek out a 100% animal free, vegan diet. Chickens are omnivores; they are scavengers. Chickens eat a variety of insects including grasshoppers, pill bugs, spiders and even fly larvae (1). In contrast, corn is the most commonly used grain and soybean meal is the main protein in conventional chicken feed (2, 3). In addition, almost all soybean and corn in conventional chicken feed is genetically modified (4).
Consumers looking to avoid genetically modified foods may choose organic foods. To meet USDA organic livestock requirements, chickens must be fed 100% certified organic feed and managed without animal by-products (5). Many consumers consider this a reasonable requirement. But, without the ability to use animal byproducts (e.g.: meat-meal), grains and soy have become the mainstay of poultry feed for industrial organic farmers. A diet high in cereal grains is typically low in methionine, an essential amino acid. Methionine deficiency can retard growth, reduce egg production, result in poor feather growth and increase feather pecking (3). To help meet methionine requirements, synthetic methionine is fed to chickens. Yes, organic chickens can be fed “synthetic substances” as defined by the USDA (6).
We are being sold meat and eggs from naturally omnivorous chickens fed an organic, 100% vegetarian, synthetic substance supplemented diet.
In 2005, Mother Earth News published the results of a survey evaluating the nutrient content of eggs from pasture raised chickens and compared them to data in the USDA nutrient database for eggs from conventionally raised chickens. They found half as much cholesterol, twice as much vitamin E, four times more omega-3 fatty acids and up to six times more vitamin A in the eggs from the pasture raised chickens (7). Another survey published in Mother Earth News in 2007 found similar results (8).
Critics of these surveys point out that the results were not published in peer-reviewed journals and subsequent studies have both supported and contradicted the claims about cholesterol and vitamin content in free range eggs (9, 10). It’s important to keep in mind that the 2015 Dietary Guidelines have eliminated cholesterol intake limits due to the lack of evidence demonstrating a significant relationship between cholesterol in the diet, cholesterol in the blood and heart disease (11, 12, 13).
Despite the conflicting evidence, consumers have demanded meat and eggs from chicken raised in a more natural setting (14). Products with claims such as “cage free”, “free roaming” and “free range” are commonly found on egg cartons.
Although the organic label and the 100% vegetarian-fed statement may imply health, there is no evidence to support that the eggs are healthier. Cage free, free range and free roaming statements do not guarantee chickens roam outside and eat a natural, omnivorous diet. Pastured poultry, as defined by the HFAC’s Certified Humane® requirement, refers to chickens raised outdoors on a pasture (18). Eggs from pastured hens may have higher levels of omega-3 fatty acids (a healthy fat), greater vitamin E content and more beta-carotene (7, 8, 9, 10).
Christine Dobrowolski is a nutritionist and whole-foods advocate.