What makes eggs controversial is not any particular aspect of this food - for example, whether they come from pastured-raised hens or whether they are organic. It is the nature of eggs themselves that makes them controversial.
Four of the most controversial aspects of eggs are (1) a disproportionate number of adverse reactions to eggs in comparison to other commonly eaten foods; (2) lack of regulatory standards needed to assure a natural lifestyle for hens who produce eggs; (3) relatively high total fat, saturated fat, and cholesterol content of eggs in comparison with many other foods, and (4) risk of egg contamination by bacteria, especially Salmonella enteritidis. Here is more information about each of those controversies.
The vast majority of eggs consumed in the U.S. come from hens (female chickens), and eggs are listed by the Centers for Disease Control as one of the eight food types most closely associated with food allergy in the U.S. These eight food types are (1) wheat, (2) cow's milk, (3) hen's eggs, (4) fish, (5) crustacean shellfish (including shrimp, prawns, lobster and crab); (6) tree nuts (including cashews, almonds, walnuts, pecans, pistachios, Brazil nuts, hazelnuts and chestnuts); (7) peanuts; and (8) soy foods.
Processed foods containing eggs (for example, muffins or waffles) must be labeled as containing a potential allergen in the same way as foods containing eggs themselves. In research studies, however, there is documentation of less allergic reaction to eggs in baked goods than in than to eggs consumed alone.
Approximately 1-2% of all U.S. children are believed to develop egg allergy, making hen's eggs only second to cow's milk in terms of allergy risk. Individuals who develop an allergic reaction to hen's eggs typically have an immune system response to either ovalbumin (OVA) or ovomucin (OVM). Both OVA and OVM are proteins naturally found in the white of all hen's eggs. However, additional reactive proteins—like ovotransferrin—have been identified in egg whites. The yolk of an egg also contains proteins that have been shown to be involved with egg allergy. These proteins include livetin, apovitillin, and vosvetin. Due to these circumstances, it is possible for a person to develop an allergy to egg whites alone, to egg yolks alone, or to both. It's not necessary, of course, to consume whole eggs, egg whites, or egg yolks directly in order to experience an allergic response. A person with egg allergy might react to whole eggs, egg whites, or egg yolks that have been incorporated into baked goods or other recipes.
Recent research studies have shown that OVA and OVM are made more digestible through cooking, as well as less likely to get transported out of the digestive tract and up into the bloodstream. For this reason, cooked eggs are associated with less allergic response than raw eggs. There is also some preliminary evidence that individuals who first consume eggs that have been incorporated into baked goods like muffins or waffles develop greater tolerance to eggs in such a way that when they eventually do have hard boiled, soft boiled, poached or scrambled eggs, they are less likely to experience an allergic reaction.
A second aspect of the egg controversy involves the lifestyle of hens that produce eggs. Today, egg production in the U.S. has reached a level of 762 billion eggs per year. Large-scale production facilities for eggs often house 30,000-50,000 hens or more. In fact, some U.S. Congressional legislation only applies to production facilities with at least 30,000 hens. At this scale of production, it is very difficult—and perhaps impossible—to provide a natural lifestyle for the egg-laying hens. Equally important, the labeling terminology on egg cartons can mislead consumers about the conditions under which the hens have been raised and the eggs have been hatched. The term "free-range," for example, means that hens that lay the eggs must have access to the outdoors but not continuous outdoor access. As an example, it's common for "free-range" hens to be kept indoors at night. In addition, "free-range" does not exclude the use of outdoor pens, which are commonly used in "free-range" facilities. "Pastured" means continuous outdoor access during both night and day, but once again does not exclude the use of pens. "Cage-free" on the label of an egg carton means what it says, although legal use of this term does not exclude indoor confinement, nor does not require outdoor access.
While organic standards for eggs do require outdoor access for hens, the exact standards for outdoor access are not well defined in the organic regulations. Organic requires strict feeding with certified organic feed, but legal use of the organic label does not require any fixed amount of feed to be obtained from a pasture setting.
The absence of a strong regulatory environment, combined with the massive scale of egg production in the commercial food supply has led to a lifestyle for many egg-laying hens that is far from natural. Time outdoors to engage in walking, nesting, pecking, wing-spreading, and other natural activities may be non-existent, as may access to natural dietary options like worms, grubs, insects, legumes, and grasses. Debeaking and forced molting are also common practices in large-scale egg production.
The pasture-raised eggs that we profile on our website contain 78 calories, 5.3 grams of total fat, 1.6 grams of saturated fat, and 212 milligrams of cholesterol. These values mean that the eggs are about 60% fat, about 19% saturated fat, and use up about 70% of a total day's dietary cholesterol allowance. If our entire daily diet—including all foods eaten throughout the day—contained this percent total fat and this percent saturated fat, our risk of many chronic diseases would go up dramatically. Most public health organizations (like the American Heart Association) recommend that we restrict our total fat intake to 35% of our calories or less, and our saturated fat intake to no more than 7% calories. So you can see how the percentage of fat and saturated fat in pasture-raised eggs might raise concern for many individuals.
However, it's important to consider the way that one pasture-raised egg might be incorporated into an overall balanced diet. On an 1,800 calorie meal plan, for example, the 1.6 grams of saturated fat found in one pasture-raised egg would represent less than 1% of total calories—far below the 7% level recommended by the American Heart Association. Similarly, the 5.3 grams of total fat in a pasture-raised egg would represent less than 3% of total calories in an 1,800 calorie meal plan. That very small percentage leaves plenty of room for many other fat-containing foods while still remaining below a 35% fat level in the overall meal plan.
The level of dietary cholesterol contained in a single egg is more difficult to fit within the American Heart Association (AHA) guidelines since only 300 milligrams are recommended for healthy individuals. (For individuals with high LDL cholesterol and/or treatment with cholesterol-lowering medications, only 200 milligrams are recommended.) Alongside of this AHA recommendation, however, is some interesting recent research to suggest that the cholesterol content of an egg may be less of a concern in relationship to heart disease than previously thought. In recent studies, no increased risk of either heart attack or stroke has been shown with intake of one to six eggs per week. (One exception has involved participants with type 2 diabetes, whose risk of heart problems was associated with egg intake, even in the range of one to six eggs per week.) Equally interesting in recent studies has been a link between egg intake and increased levels of HDL cholesterol (the "good" cholesterol). Not only has egg intake increased the number of HDL molecules, it has also improved their composition and allowed the molecules to function more effectively.
We've created a separate Q & A to provide you with detailed information about the likelihood and reasons for egg contamination, as well as practical recommendations in this area. In this Q & A, we review recent research findings related to Salmonella enteritidis, as well as other important aspects of egg safety.
While we believe that modest servings of pasture-raised eggs in the range of one to three eggs per week—especially from local farms with small flock size—may lesson some of the concerns about this food, we understand that eggs remain controversial and we respect the decision of many individuals who avoid eggs in their meal plan. We do not consider intake of pasture-raised eggs to be mandatory for anyone. At the same time, however, we recognize that some people do well when including eggs in their diet, and we want to provide as accurate information as we can about this controversial food.