|Shopping for Eggs|
|Stick with organic||Organic standards help lower risk of contaminated feed and organic eggs usually have higher nutrient quality. However, remember that organic by itself does not guarantee a natural lifestyle for the egg-laying chickens.|
|Ask for pasture-raised||Go beyond organic by asking for pasture-raised. Don't get sidetracked by the confusing array of labeling terms. You are likely to find phrases like "pasture-raised," "pastured," "free-range" and "cage-free" on egg packaging, but labeling laws allow products to display these terms even if the egg-laying chickens spend little or no time outdoors in a pasture setting. Talk to your grocer or the chicken producer and find out how the chickens were actually raised.|
|Consider local farms||Organic, pasture-raised eggs may be available from local farms with small flocks and a natural lifestyle for their chickens. Two websites that can help you find small local farms in your area are www.localharvest.org and www.eatwild.com. Both sites are searchable by zip code.|
One additional note about egg selection—we frequently get questions about the advisability of raw egg consumption. In our detailed Q & A on this topic, we review the research-based pros and cons of eating raw eggs and we provide you with some practical recommendations in this area.
Eggs have long been recognized as a source of high-quality protein. The World Health Organization (WHO) and other public health authorities actually use eggs as their reference standard for evaluating the protein quality in all other foods. Egg protein is usually referred to as "HBV" protein, meaning protein with High Biological Value. Since eggs are used as the reference standard for food protein, they score 100% on the HBV chart. The high quality of egg protein is based on the mixture of amino acids it contains. (Amino acids are the building blocks for making proteins.) Eggs provide a complete range of amino acids, including branched chain amino acids (leucine, isoleucine, valine), sulfur-containing amino acids (methionine, cysteine), lysine, tryptophan, and all other essential amino acids. Their protein is sometimes referred to as a "complete protein" for this reason.
All B vitamins are found in eggs, including vitamins B1, B2, B3, B5, B6, B12, choline, biotin, and folic acid. Choline is a standout among these B vitamins. In fact, eggs rank higher in choline than any of our other WHFoods. In the U.S., an average diet provides about 300 milligrams of choline per day - less than the recommended amount for an adult woman (425 milligrams) or an adult man (550 milligrams). Since one egg provides over 100 milligrams of choline and only 75-80 calories, it provides far more choline for far less calories than most other choline-rich foods.
The mineral content of eggs also deserves special mention here--not because eggs are a rich source of most minerals but because they are a rich source of certain minerals that can sometimes be difficult to obtain from other foods. Eggs are a very good source of both selenium and iodine. While many fish, shellfish, and mushrooms can be rich sources of selenium, persons who avoid these foods may sometimes have difficulty getting an adequate amount of this important antioxidant mineral from food. For persons who do not use iodized salt in recipes or at the table and who do not consume either yogurt or cow's milk, this mineral can also sometimes be challenging to obtain from food.
The nutrients found in an egg are distributed fairly evenly between the yolk and the white. This distribution of nutrients is a common characteristic of whole, natural foods and it is one of the reasons that we recommend consumption of whole eggs (except, of course, when only the yolk or the white is called for in a recipe). The chart below explains what approximate percent of the total nutrient amount is found in the yolk and the white of an egg. You will notice that the first four nutrient groupings are those that are found predominately in the egg white, while those that follow are found predominately in the egg yolk (all except for the last nutrient, selenium, which is divided fairly evenly between the egg white and yolk).
|Nutrient||Egg White||Egg Yolk|
|Magnesium, Potassium, Sodium||10-25%|
|Vitamins A, D, E, K||0%||100%|
|Vitamins B5, B6, B12, Folate, Choline||10% or less||90% or more|
|Calcium, Phosphorus, Zinc, Copper, Iron||10% or less||90% or more|
In recent years, there has been a food marketplace trend of greater availability of eggs that are unusually rich in omega-3 fats. These eggs get their high levels of omega-3s through the addition of omega-3 oils to the hen's feed. Oils added to the hen's diet as a way of increasing omega-3s include menhaden oil, krill oil, flaxseed oil, and algae oil. The supplementation of the hen's diet with these oils usually produces as much as 250 milligrams of omega-3s per egg yolk.
What many consumers do not know is that virtually all egg yolks contain omega-3 fats and that by providing hens with a natural, pasture-based diet their omega-3 levels can be naturally increased. Pasture feeding can provide the hen with clover and alfalfa, two examples of legumes that are rich in omega-3s; in fact, pasture feeding can double the amount of omega-3s in an egg yolk. Omega-3s are far too low in the average U.S. diet, and eggs from pasture-raised chickens can provide significant amounts of these anti-inflammatory fats.
As a group, research studies on the health benefits of eggs have shown mixed results. Part of the difficulty that researchers encounter when trying to determine the pros and cons of egg intake is the tendency of participants to consume other foods high in fat and/or saturated fat along with eggs. For example, at breakfast meals in the U.S., eggs are often consumed together with bacon, sausage, or ham. This simultaneous consumption of eggs with other foods can make it difficult for researchers to separate out the specific influence of the eggs. In addition, from a calorie standpoint, two eggs typically provide only 150-175 calories—only 7-8% of a 2,000-calorie diet. This small amount can make it more difficult for researchers to pinpoint the role played by the eggs.
Another complicating factor in egg research is the fiber-free nature of eggs. Since fiber typically has a risk-lowering affect for cardiovascular disease, diabetes, and cancer, egg intake might show up as problematic in a diet that was otherwise very low in fiber, yet helpful in a diet that was otherwise rich in fiber.
These factors described above do not change our view of eggs as an unusually nutrient-rich food that can provide a unique combination of nutrients for a very small number of calories. But they do underscore the importance of integrating eggs into an otherwise healthy meal plan.
In the area of cardiovascular disease, recent studies have shown no increased risk of either heart attack or stroke in conjunction with egg intake of one to six eggs per week. Interestingly, these studies have also shown the ability of egg intake to increase levels of HDL cholesterol (the "good" cholesterol). Not only did egg intake increase the number of HDL molecules, it also improved their composition and allowed them to function more effectively. This improved function may have been the result of more phosphatidylethanolamine being added to the HDL molecules. (The addition of phosphatidylethanolamine, in turn, might have been related to the rich initial choline content of the eggs.)
Not all egg studies show potential cardiovascular benefits, however, and in some studies, egg intake has been related to some increased mortality risk. However, as mentioned previously, it's been difficult for researchers to separate out the possible role of other foods in many studies. Particularly in mortality studies, which often examine diet in very general terms, they are unable to look closely at specific egg amounts in the diet.
One further note about the relationship between egg intake and cardiovascular risk: some persons with type 2 diabetes may be more susceptible to unwanted cardiovascular problems in relationship to egg intake if their type 2 diabetes has also created problems with cholesterol transport through the bloodstream. (These transport problems often correspond to low levels of apolipoprotein E and high levels of apolipoprotein C-III in the blood, which can be determined by lab testing.) Given this connection, persons with type 2 diabetes are encouraged to consult with their healthcare provider when making decisions about eggs in their meal plan.
Like studies on eggs and cardiovascular risk, studies on eggs and cancer risk have been mixed. We have seen large-scale studies in which egg intake was associated with a decreased risk of breast cancer and included along with vegetables, fruits, and legumes as a desirable factor in a risk-lowering meal plan. Yet we have also seen studies in which risk of colon and rectal cancer was increased by egg intake. For us, the mixed nature of these cancer studies underscores the need to consider health benefits of eggs as being conditional upon the overall quality of the diet; we should not be assuming that eggs will automatically lower or raise cancer risk regardless of an overall meal plan.
We include eggs as one of our WHFoods because of the broad nourishment they provide, their unique combination of nutrients (including omega-3s, antioxidant minerals like selenium, and high biological value protein), and their low calorie cost. Eggs are a nutrient rich, natural, whole food. At the same time, research on eggs has not always shown them to provide health benefits, and in some situations (for example, individuals with type 2 diabetes who are trying to lower their risk of cardiovascular problems) eggs may not be appropriate as part of a routine meal plan. So even though eggs are a natural, nutrient rich whole food, we do not consider them mandatory in any meal plan.
If you do decide to consider the addition of eggs to your meal plan, we encourage you to take a close look at your overall diet. Could it use more protein? If so, eggs might make sense. Does it already have plenty of fiber? If not, it might make more sense to add a fiber-containing food rather than eggs. We're confident that in many diets, pasture-raised eggs can provide key nutrient benefits and lower your disease risk, despite some of the confusion that we've come across in the food science research.
It is common to hear eggs being lumped together with dairy foods and referred to as "eggs and dairy." In fact, we group eggs and dairy foods together this way on our website. It is important, however, to understand how eggs are unique as a food. Chickens—and the eggs laid by female chickens (hens)—belong to the bird class of animals (Aves). Hen's eggs are one among many types of bird eggs enjoyed in diets worldwide. Eggs from ducks, geese, quail, turkeys, and ostriches are also part of many cuisines. Birds (including chickens) are omnivores, which means that they eat both meat and plants. Hens, for example, often enjoy eating insects, insect larvae (grubs), and worms. Some of this intake helps explain the unique combination of nutrients found in eggs.
The dairy foods we profile on our website come from cows, which belong to an entirely different class of animals (mammals) than chickens. Unlike hens, cows are herbivores (exclusively plant eating) with a complex digestive system (called a ruminant digestive system) that is designed for lots of chewing and fermentation of grasses, legumes, and other forage plants. Because of their grass-based digestive system, cows provide us with foods (including milk, cheese, yogurt, and beef) that are healthiest when the cows have been grass-fed. However, since hens are birds rather than ruminants and not primarily designed to eat grass (even though hens often do eat grass and enjoy it), we describe eggs on our website as "pastured-raised" instead of "grass-fed."
Chicken eggs are by far the most common type of egg consumed in the U.S., and the breeding of chickens for egg production has resulted in breeds that can lay 200-300 eggs per hen per year. Some of the more popular egg-laying breeds include White Leghorns, Rhode Island Reds, Buff Orpingtons, Golden Coments, Red Sex Links, Isa Browns, Australorps, Black Star, Red Star, Light Sussex, and Plymouth Rock. All of these breeds belong to the same genus, species, and subspecies of animal, namely, Gallus gallus domesticus. You may also hear chickens being referred to as "junglefowl," which is a common name for all animals belonging to the Gallus genus.
The composition of an egg is usually described as having two basic parts: the white and the yolk. The white is approximately 87% water and 13% protein, and contains both vitamins and minerals. The yolk is about 50% water, 33% fat, and 17% protein; like the white, it also contains both vitamins and minerals. Please see our Health Benefits section for a more detailed description of the nutrients found in each part of the egg.
Egg grading standards are based on the clearness, firmness, and thickness of the white, the presence or absence of defects in the yolk (like blood spots or meat spots), the size of the air cell inside of the shell (the smaller this air space, the higher quality the egg), and the cleanness of the shell, including the absence of any slight breakage. Eggs that score highest on these qualities are graded "AA." Fairly close in quality are "A" eggs. The shelf life of an egg is related to its grade, and a fresh AA egg will have a longer shelf life than a fresh A egg. However, an egg's grade is not the same as its freshness. For more information on egg grading and freshness - including our practical recommendations - please see our How to Select and Store section.
The size of an egg is related to its weight. The chart below provides a summary of the standards used to label eggs as small, medium, large, extra large, or jumbo.
|Average weight per egg (in grams)||Average weight per egg (in ounces)|
As mentioned in our Description section, bird eggs (including chicken eggs) have long held a place in cuisines worldwide. The variety of bird eggs enjoyed in many cultures includes duck, goose, quail, turkey, and ostrich eggs. With respect to their history, it's also worth noting that birds were not the first animals to reproduce by means of shell eggs. Reptiles were the first animals to do that, nearly 150 million years before the first shell eggs produced by birds.
Eggs have always had a primary place in mythologies, religions, and cultural practices worldwide, and have typically been regarded as symbols of rebirth, renewal, beginnings, and fertility. One of the most widely held food and holiday associations is that of the Easter egg. How the egg became associated with this holiday seems to have roots that are both biological and cultural. Before the more modern techniques of poultry raising, hens laid few eggs during the winter. This meant that Easter, occurring with the advent of spring, coincided with the hen's renewed cycle of laying numerous eggs. Additionally, since eggs were traditionally considered a food of luxury, they were forbidden during Lent, so Christians had to wait until Easter to eat them—another reason eggs became associated with this holiday. Interestingly enough, the custom of painting eggshells has an extensive history and was a popular custom among many ancient civilizations, including the Egyptians, Chinese, Greeks, and Persians.
Today, egg production in the U.S. has reached a level of 762 billion eggs per year. About 70% of these eggs are sold and purchased in whole form, and about 30% are removed from shells at "breaker plants" across the country and converted into egg products, including both liquid and dried yolks and whites. Iowa, Ohio, Pennsylvania, Indiana, and California are the country's top five egg-producing states. On a global basis, the U.S. is the largest egg-producing country in the world, followed by Mexico and Brazil. However, small numbers of eggs are produced in most countries worldwide, and out of the world's total (63.7 million tons of hen's eggs), only 20% (12.8 million tons) are produced in all North American, Central American, and South American countries combined.
Labeling terms that appear on egg packaging are among the most confusing and misleading for any food type. You might find all of the following terms on the label of an egg carton:
Unfortunately, while legal, some of these labeling terms are also misleading. The term "free-range," for example, means that the hens who lay the eggs must have access to the outdoors—but the emphasis here is on "access." No standards are set for how often the hens actually go outside, how much time they must stay outside if they do go out, or what the outdoor environment must include in terms of total space or vegetation. "Pastured" and "pasture-raised" are similarly misleading terms that are not backed up by standards for actual time spent by hens in a pasture setting or standards for qualifying an outdoor space as "pasture." Use of the term "cage-free" on the label of an egg carton means what it says—but legal use of this term does not require hens to have any access to outdoor space and therefore may be used when hens have been confined indoors full-time.
When an egg carton displays the USDA organic logo, you still cannot be certain that chickens have spent much time outdoors. Organic standards for eggs do require outdoor access for hens, but the exact standards for outdoor access are not well defined. For example, no minimal amount of days spent outdoors or time per day spent outdoors is specified. Organic standards require 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. These limitations of the organic logo are one more reason that we encourage you to talk with your grocer or egg producer and find out how the chickens were actually raised.
Another confusing aspects of egg selection is deciding about an egg's freshness before you purchase it. Unfortunately, the labeling on an egg carton cannot help you make a clear decision about freshness. An expiration date for the eggs is usually stamped on the side of the carton, often with the abbreviation "EXP" (e.g., EXP Jan23) However, this expiration date is calculated from the time of packaging not from the time when the egg was laid by the hen. (Thirty days is the maximum amount of time allowed between the packing date and the expiration date.) Since you would want to know time from egg laying in order to determine freshness, the expiration date cannot help you here as much as you would like.
As presented in more detail in our Description section, eggs that score highest on certain qualities are graded "AA." Fairly close in quality are "A" eggs. The shelf life of an egg is related to its grade, and a fresh AA egg will have a longer shelf life than a fresh A egg. In and of itself, however, a grade of AA does not tell you that an egg is fresh, since the egg grading system does not take the time of laying into account. If an AA egg is fresh, it will stay fresh longer than an A egg. But this benefit of an AA egg still does not tell us whether an AA egg is fresh in the first place.
Because of these limitations in the grading system and expiration date assignment for eggs, we recommend that you talk either with your grocer (depending on his or her knowledge of the situation) or the farm itself to determine the freshness of your eggs. In some situations, there may only be several days between the laying of an egg and its appearance in the dairy section of your grocery. In other situations, there might be three weeks or more. As we have discussed previously in this profile, another alternative is to purchase eggs directly from a small local farm that sells to consumers.
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:
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.
Inspect any eggs that you purchase for breaks or cracks. And of course, take care when packing them in your shopping bag for the trip home as they are very fragile.
Always store eggs in the refrigerator. Although eggs will often be safe to consume after the expiration date on the egg carton, we nevertheless recommend consumption of eggs by the designated expiration date for optimal safety and better freshness. When refrigerating eggs, do not wash them as this can remove their protective coating. Keep them in their original carton or in a covered container so that they do not absorb odors or lose any moisture. Do not store them in the refrigerator door since this exposes them to too much heat each time the refrigerator is opened and closed. Make sure to store them with their pointed end facing downward as this will help to prevent the air chamber, and the yolk, from being displaced.
For some of our favorite recipes, click Recipes.
Eggs are among the eight food types considered to be major food allergens in the U.S., requiring identification on food labels. For helpful information about this topic, please see our article, An Overview of Adverse Food Reactions.
Health safety concerns about eggs center on salmonellosis (salmonella-caused food poisoning). Salmonella bacteria from the chicken's intestines may be found even in clean, uncracked eggs. You'll find these issues discussed in detail in our Q & A about raw versus cooked eggs. As a general rule, there is more risk associated with soft cooked and "sunny side up" eggs than eggs that have been hard boiled, scrambled, or poached.
Dishes and utensils used when preparing eggs should be washed in warm water separately from other kitchenware, and hand washing with warm, soapy water is essential after handling eggs. Any surfaces that might have potentially come into contact with raw egg should be washed and can be sanitized with a solution of 1 teaspoon chlorine to 1 quart water.
Raw egg whites contain a glycoprotein called avidin. Avidin has a unique preference for binding together with one particular B vitamin—biotin—and when it does, an avidin-biotin complex is formed that is unable to be absorbed from our digestive tract. As a result, we do not get the biotin nourishment that we would otherwise get from the food. Hen's eggs average about 10 micrograms of biotin. Two micrograms are found in the white (where the avidin glycoprotein is also located), and 8 micrograms are found in the yolk. Since cooking is able to denature the avidin glycoprotein in an egg white, cooking also makes this glycoprotein unable to bind together with biotin in either the white or the yolk and prevent its absorption. The Daily Value (DV) for biotin is 300 micrograms, and since the total amount of biotin in one egg is only 10 micrograms, it would not be logical for a person to depend on his or her egg intake to meet the biotin DV. However, loss of biotin nourishment from an egg could still be prevented through cooking, based on food science research in this area.
Some animal foods and some plants foods have been the subject of ongoing controversy that extends well beyond the scope of food, nutrient-richness, and personal health. This controversy often involves environmental issues, or issues related to the natural lifestyle of animals or to the native habitat for plants. Eggs has been a topic of ongoing controversy in this regard. Our Controversial Foods Q & A will provide you with more detailed information about these issues.
Eggs, pasture-raised, large, hard boiled
|selenium||15.40 mcg||28||6.5||very good|
|biotin||8.00 mcg||27||6.2||very good|
|vitamin B12||0.55 mcg||23||5.3||very good|
|vitamin B2||0.26 mg||20||4.6||very good|
|molybdenum||8.50 mcg||19||4.4||very good|
|iodine||27.00 mcg||18||4.2||very good|
|pantothenic acid||0.70 mg||14||3.3||good|
|vitamin D||43.50 IU||11||2.5||good|
|vitamin A||74.50 mcg RAE||8||1.9||good|
Density>=7.6 AND DRI/DV>=10%
Density>=3.4 AND DRI/DV>=5%
Density>=1.5 AND DRI/DV>=2.5%