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What are the pros and cons of raw eggs?

Consumption of raw eggs has been a long-standing controversy among U.S. consumers, even though public health organizations have unanimously recommended the cooking of eggs and egg products to lower the risk of illness from contamination. We'd like to give you more information on both sides of the equation (both pro and con) to help you make a more informed decision if you are thinking about the addition of raw eggs to your meal plan.

Possible Benefits from Raw Eggs

Like most foods, eggs undergo some loss of nutrients when they are cooked. This nutrient loss occurs regardless of whether the egg is removed from the shell (for example, during poaching) or left inside the shell during cooking (for example, during soft or hard boiling). If you compare the nutrient value of one large raw egg to one large hard-boiled egg in the latest version of the U.S. Department of Agriculture's nutritional database, you will find the following potential advantages to be offered by a raw egg:

  • 36% more vitamin D
  • 33% more omega-3s
  • 33% more DHA (docosahexaenoic acid)
  • 30% more lutein + zeaxanthin
  • 23% more choline
  • 20% more biotin
  • 19% more zinc

For some of these nutrients, the greater percentage in a raw egg may not make for a practical difference, since the egg starts out with too little of the nutrient in the first place. For example, even though the amount of vitamin D in a raw egg drops from 41 IU to 26.5 IU during hard boiling, a raw egg only provides 10% of the Daily Value (DV) for vitamin D to begin with, with this percentage dropping down to 7% through the process of boiling. From our perspective, regardless of whether you are getting 10% of the DV from a raw egg or 7% from a hard-boiled egg, you clearly don't want to rely on eggs for your vitamin D nourishment.

For other nutrients, however, loss during cooking might make a practical difference. In the case of choline, for example, a woman would get nearly 35% of her Adequate Intake (AI) level from a single raw egg, as compared with about 26% from a hard-boiled egg. While this required B-vitamin is found in smaller amounts in a variety of foods, the average U.S. intake for choline is only 302 milligrams per day, making it important for U.S. adults to maximize their dietary intake whenever possible. (It's also worth noting here that among all of our WHFoods, egg comes out on top in terms of its choline content.) In summary, there are several nutritional benefits that could be obtained from consumption of raw eggs.

Possible Drawbacks Associated with Raw Eggs

By far the most troublesome risk associated with raw eggs is contamination, and particularly by specific bacteria called Salmonella enteritidis (SE). Many types of bacteria are naturally present not only on the shell of an egg but also inside the shell. These types of bacteria often include Campylobacter, Enterococcus, Listeria, and Salmonella. When hens are healthy, these bacteria have populations that stay in balance and do not pose a danger to the hens. However, these same-sized populations of bacteria might pose a health risk to us. As mentioned above, one particularly problematic species of bacteria present in some eggs is Salmonella enteritidis (SE). As recently as 2010, following several hundred confirmed cases of sickness across the country, the Food and Drug Administration (FDA) recalled over 500 million eggs in the U.S. due to contamination with SE.

This recall by the FDA was not a first-time event with respect to eggs. Large-scale recalls of eggs also took place in the 1980's when eggs from nearly 45% of all egg-laying hens in the U.S. had been determined to have SE contamination. Increased attention to SE risk actually began during the 1960's, not only in the U.S. but in other countries as well. Concern over SE prompted the U.S. Congress to pass the Egg Products Inspection Act (EPIA), which required egg producers to follow strict safety procedures in the handling and processing of eggs and egg products. Implementation of EPIA was followed by a vast decrease in the presence of SE on the shells of eggs; to this day, risk SE infection caused by shell surface contamination is very low. (It would be quite common, for example, to find about 1,000 colony forming units—CFU—of SE on the outside of an eggshell prior to cleaning, but to find only 10-25 CFU after cleaning.) However, implementation of these egg safety practices did not have the same effect on the presence of SE inside the eggshells. Because SE can enter into the ovary of the hen and establish presence in the egg prior to formation of the shell, careful cleaning of the shell does not lower risk of SE contamination inside the shell. In fact, most cases of egg-based salmonellosis (salmonella infection) among U.S. adults in children are caused by SE in the egg yolk or egg white, not SE on the eggshell.

Since the 1970's, the total number of annual SE infection cases among children and adults in the U.S. has varied from about 140,000 to 300,000. This relatively large number of cases is related in part to the large number of eggs produced and consumed in the U.S. At present, the average U.S. adult consumes about five eggs per week. About 762 billion eggs are produced in the U.S. each year, and nearly 30% of these eggs (228 billion) are processed at "breaker plants" into egg products. (Egg products are whites, yolks, or white/yolk combinations removed from the shell.)

Estimates of SE contamination in eggs range from 1 out of every 20,000 eggs at the higher end to 1 out of every 30,000 eggs at the lower end. If we use the higher end estimate, we would predict that in a city the size of New York (8.25 million people), about 412 contaminated eggs would be consumed each day. In a smaller city like Baltimore (619 thousand people), we'd expect to find about 31 contaminated eggs per day. On an individual basis, a person who eats 1 egg per day would expect to consume 1 contaminated egg every 54 years.

While every individual must make his or her own judgment call about these "odds," from our perspective, it doesn't make sense to think about the health benefits of a whole, natural food in terms of "odds." We like to think about whole, natural foods as fully health supportive foods, and when we hear discussions about "playing the odds," we have to wonder whether the foods in question are truly whole, natural foods. At the end of this article, we'll give you our practical recommendations about these risk-related aspects of raw eggs.

Underlying Reasons for SE Contamination

Researchers have established several basic areas of consensus about the reasons for SE contamination in eggs. High on the list of underlying reasons are unsanitary conditions in the raising of chickens. During the 2010 SE outbreak involving large flocks on Iowa farms, for example, manure was often found overflowing through barn doors from tall dung heaps inside of barns, along with the presence of flies and maggots both inside and outside the barns. It was determined that the chickens straying and pecking in these areas became infected with SE in this way. Spread of infection among hens is increased when a large number are confined to a small space, and SE outbreak problems in 2010 have also been tied to large-scale production facilities, often housing 50,000 hens.

The United Egg Products (a cooperative representing 95% of egg-laying hen farms in the U.S.) and The Humane Society of the U.S. have both endorsed a new Congressional Amendment to the 1970 Egg Products Inspection Act that will gradually establish healthier living circumstances at hen farms throughout the U.S. If this Amendment is voted on and passed by the U.S. Congress, it should help reduce risk of SE contamination in U.S. eggs. However, this Amendment is not designed to change the number of hens housed on a farm, nor to bring a broad spectrum of lifestyle changes into the hen farms.

England is a country that has taken some interesting steps to lower risk of egg contamination with some early success. First, the egg industry there has established some mandatory codes of practice that require vaccination of hens against Salmonella if producers want to display an industry-sponsored red lion stamp on their eggs. Even though this requirement is not a governmental one, nearly 90% of egg producers have adopted this approach since many large supermarkets will only purchase eggs with the red lion stamp. Since introducing this practice, the rate of reported human illness from SE contaminated eggs has decreased by over 90%.

A second practice has involved the rapid cooling of eggs after they have been laid by the hens. As described earlier, SE bacteria are naturally present on most eggshells, but in relative small numbers. However, with sufficient warmth, SE populations will double every 20 minutes, and after 8 hours, can reach the level of millions of CFUs (colony forming unites). With rapid cooling of eggs, these dramatic increases in the number of SE on eggshells can typically be prevented.

When considering the reasons for SE contamination of eggs, it's important to remember that neither organic eggs nor "free-range" nor "pastured" eggs are automatically guaranteed to be lower in SE risk than conventional eggs. In fact, some studies have shown "free-range" eggs to be a more likely source of Campylobacter exposure (Campylobacter is the type of bacteria most commonly responsible for bacteria-caused diarrhea in the U.S., with about 2 millions cases each year) than caged eggs. From a labeling standpoint, "free-range" means required outdoor access, but not continuous outdoor access. For example, "free-range" hens are usually kept indoors at night. In addition, "free-range" does not exclude the use of outdoor pens, which are commonly used in "free-range" facilities. In terms of labeling, "pastured" means continuous outdoor access during both night and day, but once again does not exclude the use of pens. When you see "cage-free" on an egg label, it means what it says, but does not exclude indoor confinement or require outdoor access.

"Organic" standards do require outdoor access, but the exact standards for outdoor access are not well defined in the organic regulations. "Organic" also requires strict feeding with certified organic feed, but it does not require that any fixed amount of feed be obtained on a pasture versus feed supplement and/or feed additive basis.

None of the labeling terms above is sufficient to assure you of non-contaminated eggs. However, we believe that some of the above terms are more helpful than others when it comes to the selection of eggs with lower contamination risk. With respect to "cage-free," "free-range," and "pastured," we don't feel confident in making a conclusion about contamination risk without know the quality of the hens' environment. A contaminated pasture is just as likely to increase the risk of contamination from a pastured egg as it is to decrease it. And while the presence of a cage is likely to make a hen less healthy, the lifestyle for a "cage-free" hen might be equally unnatural and unhealthy. In comparison to these labeling terms, we believe that "organic" more closely corresponds to decreased contamination risk, for two reasons. First, even though there is no requirement in the organic regulations to keep flock size below any fixed number, organic egg producers do tend to limit the size of their flocks and that helps lower contamination risk. Second, since organic eggs must come from hens fed organic feed, their diet should remain more toxin free and better able to support their health. Still, the labeling term "organic" is not enough to assure you of low-risk eggs.

Relationship of Safety to Appearance and Smell

Although it is possible to detect some aspects of egg safety from visual inspection of an egg and evaluation of its odor, in the key area for egg safety - contamination of an egg with Salmonella enteritidis (SE) bacteria—our sense of sight and smell are of no help whatsoever in determining the likelihood of SE contamination. While SE bacteria are larger than viruses, they are still invisible to the naked eye and cannot be seen without a microscope. The steps used by public health agencies for detecting the presence of SE in eggs or hen houses are complicated and involve complicated lab techniques. Gene typing, antibiotic susceptibility testing, culture methods, and biochemical marker testing are basic methods used to determine the presence of SE. Here are some factors to look for when inspecting an egg and their relationship to egg safety.

  • Cloudiness of egg whites: The white of a fresh egg is naturally cloudy. This cloudiness is mostly due to the presence of dissolved carbon dioxide and the suspension of albumen proteins in the watery liquid that forms the white. As an egg ages, carbon dioxide will escape through pores in the shell and the white will may also become less acidic. These changes are typically associated with a clearing of the white and less cloudy appearance. The bottom line: you can generally use the cloudiness of the egg white to help confirm freshness, with cloudy whites indicating fresh eggs. But degree of cloudiness has no relationship to SE contamination. Since we recommend consumption of eggs that are as fresh as possible, we encourage you to look for egg whites that are cloudy in appearance.
  • Yolk firmness and color: Yolk color is mostly related to the hen's diet. If the hen eats more pigmented plants (for example, the petals of flowers with orange or yellow pigments or yellow corn), the yolk will typically be darker and richer in color. By contrast, if the hen eats large amounts of white corn in her feed, the yolk will be less colorful. Like the white of an egg, its yolk will undergo changes as it ages. Over time, the yolk membrane will weaken, and the yolk will become flatter. Once again, these features can help you confirm an egg's degree of freshness, but they are not related to the presence or absence of SE. We recommend eating eggs from pasture-raised hens, and the yolks of those eggs are more likely to be richer in color from the natural diversity of pasture plants.
  • Red blood spots on the yolk: These spots are caused by the breaking of a blood vessel along the surface of the yolk. This type of breakage can occur naturally and is not a sign of contamination. We are not aware of any research showing safety risks from cooked eggs with blood spots.
  • Pinkish egg whites: If the egg white has a pinkish color, it is usually a sign of bacterial spoilage, and the bacterium most often involved is Pseudomonas. While other spoilage bacteria like coliform or Flavobacterium can play a role in egg white discoloration, pinkish egg whites are not a sign of SE. You should discard eggs if you find pinkish whites inside.
  • Off odors: Many different types of spoilage bacteria will produce off-odors in eggs. These off odors may be sulfur-like, or they might simply just smell "bad." Off odors from an egg cannot be used, however, to help determine the presence or absence of SE. But despite the lack of a relationship between a bad smelling egg and SE, we recommend that you discard all eggs with off odors due to a variety of unwanted qualities.

In summary, most visible characteristics of an egg are related to freshness, the breed of the hen and her genetics, and her diet. None of these characteristics can help you determine the presence or absence of SE. That's why it is so important to find very high-quality small local farms or very high quality larger scale egg producers when trying to minimize your risk of exposure to SE contaminated eggs.

Egg Allergy

One final topic that we would like to address about the potential cons of raw eggs is egg allergy. Hen's eggs are one of the most common allergy-related foods in the U.S. diet, and approximately 1-2% of all U.S. children develop egg allergy. 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 both.

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. Of course, if you already know that you do not experience any allergic reaction to raw eggs, then this increased allergy risk from raw eggs is not an issue. However, if you have a history of eating cooked eggs without developing an allergic response, it might still be possible for you to experience an allergic response to raw eggs.

For more on the subject of food allergies and other adverse food reactions, please see this article.

WHFoods Recommendations

There's a close relationship between the quality of all foods that we eat and the natural environment. For example, the nourishment we get from plant foods depends on the quality of the soil in which they grow. The same is true for animal foods, including eggs. The nourishment we get from an egg depends on the lifestyle of the hen who produced it—including the hen's access to pasture, fresh air, and a high-quality, natural diet. Unfortunately, no current labeling standard guarantees excellent lifestyle conditions for an egg-producing hen. Of the available labeling options, "organic" comes closest, even though it still falls short of the standard we believe it should support. Since the egg production industry is currently in a process of transition, we believe that it may eventually be possible for us to support consumption of raw eggs as a possible step in your meal plan based on improved industry standards and labeling guarantees. However, at this point in time, we cannot offer a general guideline of support to raw egg consumption; as such, we recommend that you cook all egg and egg products for safety reasons. A cooking temperature that allows the yolk and white to reach 160°F (71°C) is necessary in order to kill SE bacteria that may be present.

If you do plan to include raw eggs in your meal plan, we recommend that you locate and purchase eggs from a farm in your area that not only produces certified organic eggs but also take steps to ensure a genuinely natural lifestyle for the hens, including a pasture-based diet from a natural landscape with ecologically balanced vegetation. For help in locating a small organic and sustainable egg producer in your area, we recommend that you visit both of the following websites.

Each of these websites (Eat Wild and Local Harvest) maintains an up-to-date listing of local farms and is searchable by zip code.

References

  • Caubet JC, Bencharitiwong R, Moshier E, et al. Significance of ovomucoid- and ovalbumin-specific IgE/IgG4 ratios in egg allergy. Journal of Allergy and Clinical Immunology, Volume 129, Issue 3, March 2012, Pages 739-747
  • Cornucopia Institute. (2010). Scrambled Eggs: Separating Factory Farm Egg
  • Production from Authentic Organic Agriculture. A Report and Scorecard by The Cornucopia Institute. Cornucopia, WI.
  • Egg Products Inspection Act (EPIA). (1970). 21 USC Section 1032 (112-190), Title 21, Chapter 15. Congressional Record, pages 577-589.
  • Food Safety and Inspection Service (FSIS). Shell eggs from farm to table. U.S. Department of Agriculture, April 2011.
  • Gast R and Guard J. Controlling egg contamination with salmonella enteritidis by understanding its pathobiology. Agricultural Research Service, U.S. Department of Agriculture. XXII Latin American Poultry Congress 2011.
  • Gast RK, Guraya R, Guard J, et al. Multiplication of Salmonella enteritidis in egg yolks after inoculation outside, on, and inside vitelline membranes and storage at different temperatures. J Food Prot. 2010 Oct;73(10):1902-6.
  • Heckman J. Chicken Tractoring on the Home Turf. Proceedings of the Seventeenth Annual Rutgers Turfgrass Symposium. January 10-11, 2008. The Center for Turfgrass Science, Rutgers University.
  • Jones DR, Anderson KE, and Guard JY. (2012). Prevalence of coliforms, Salmonella, Listeria, and Campylobacter associated with eggs and the environment of conventional cage and free range egg production. Poultry Science. 91:1195-1202. doi: 10.3382/ps.2011-01795.
  • Konstantinou GN and Kim JS. Paradigm Shift in the Management of Milk and Egg Allergy: Baked Milk and Egg Diet. Review. Immunology and Allergy Clinics of North America, Volume 32, Issue 1, February 2012, Pages 151-164.
  • Latimer HK, Marks HM, Coleman ME, et al. Evaluating the effectiveness of pasteurization for reducing human illnesses from Salmonella spp. in egg products: results of a quantitative risk assessment. Foodborne Pathog Dis. 2008 Feb;5(1):59-68. doi: 10.1089/fpd.2007.0041.
  • Leonard SA, Sampson HA, Sicherer SH, et al. Dietary baked egg accelerates resolution of egg allergy in children. Journal of Allergy and Clinical Immunology, Volume 130, Issue 2, August 2012, Pages 473-480.e1
  • Martos G, Lopez-Exposito I, Bencharitiwong R, et al. Mechanisms underlying differential food allergy response to heated egg. Journal of Allergy and Clinical Immunology, Volume 127, Issue 4, April 2011, Pages 990-997.e2
  • Mazurek J, Holbert L, Parrish MK, et al. Raw eggs - lessons learned from an outbreak of Salmonella serotype enteritidis infections associated with meringue pie. J Public Health Manag Pract. 2005 May-Jun;11(3):201-7.
  • Reu KD, Messens W, Heyndrickx M, et al. Bacterial contamination of table eggs and the influence of housing systems. World's Poultry Science Journal 2008, Vol. 64, pages 5-19.
  • Savage JH, Matsui EC, Skripak JM, at el. The natural history of egg allergy. Journal of Allergy and Clinical Immunology, Volume 120, Issue 6, December 2007, Pages 1413-1417.
  • Schroeder CM, Latimer HK, Schlosser WD, et al. Overview and summary of the Food Safety and Inspection Service risk assessment for Salmonella enteritidis in shell eggs, October 2005. Foodborne Pathog Dis. 2006 Winter;3(4):403-12.
  • Seo KH, Holt PS, Stone HD, et al. Simple and rapid methods for detecting Salmonella enteritidis in raw eggs. International Journal of Food Microbiology, Volume 87, Issues 1—2, 15 October 2003, Pages 139-144.
  • U.S. Food and Drug Administration. (FDA). Environmental Sampling and Detection of Salmonella in Poultry Houses. Silver Spring, MD. October 2008.
  • USDA Food Search for Windows, Version 1, Database Version SR 25. (2012). Nutrient Data Laboratory (NDL), Beltsville Human Nutrition Research Center (BHNC), Agricultural Research Service (ARS), U.S. Department of Agriculture (USDA).

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