raw egg

Can you eat a raw egg ?

egg composition

The Danger of Eating Raw Egg

Salmonella infection (salmonellosis) is a common bacterial disease that affects the intestinal tract. Salmonella bacteria typically live in animal, birds and animals  intestines and are shed through feces. Humans become infected most frequently through contaminated water or food.

Salmonella infection is usually caused by eating raw or undercooked eggs, meat, poultry or egg products. The incubation period ranges from several hours to two days.

  • The inside of eggs that appear normal can contain a germ called Salmonella that can make you sick, especially if you eat raw or lightly cooked eggs. Eggs are safe when you cook and handle them properly.
  • No one should eat foods containing raw eggs. This includes “health food” milk shakes made with raw eggs, Caesar salad, Hollandaise sauce, and any other foods like homemade mayonnaise, ice cream, or eggnog made from recipes in which the egg ingredients are not thoroughly cooked.

Researchers say that, if present, the Salmonella Enteritidis bacteria can be in the yolk or “yellow” or the albumen (egg whites). While an egg’s shell may seem to be a perfect barrier to contamination, some infected chickens produce eggs that contain salmonella before the shell is even formed. So everyone is advised against eating raw or undercooked egg yolks and whites or products containing raw or undercooked eggs. Raw eggs are used in homemade versions of mayonnaise and hollandaise sauce.

Poultry may carry bacteria such as Salmonella that can contaminate the inside of eggs before the shells are formed. Eggs can also become contaminated from the droppings of poultry 1). Shell eggs may become contaminated with Salmonella through the laying process, once the eggs are laid, through poultry feed or bedding.

Bacteria can be on the outside of a shell egg too. That’s because the egg exits the hen’s body through the same passageway as feces is excreted. That’s why eggs are required to be washed at the processing plant. All USDA graded eggs and most large volume processors follow the washing step with a sanitizing rinse at the processing plant. It is also possible for eggs to become infected by Salmonella Enteritidis fecal contamination through the pores of the shells after they’re laid. SE also can be inside an uncracked, whole egg. Contamination of eggs may be due to bacteria within the hen’s reproductive tract before the shell forms around the yolk and white. SE doesn’t make the hen sick.

Most salmonella infections can be classified as stomach flu (gastroenteritis).

The U.S. Food and Drug Administration (FDA) estimates that 79,000 cases of foodborne illness and 30 deaths each year are caused by eating eggs contaminated with Salmonella 2). FDA has put regulations in place to help prevent contamination of eggs on the farm and during shipping and storage, but consumers also play a key role in preventing illness linked to eggs. Protect yourself and your family by following these safe handling tips when buying, storing, preparing, and serving eggs—or foods that contain them.

FDA requires all cartons of shell eggs that have not been treated to destroy Salmonella to carry this safe handling statement:

“Safe Handling Instructions
To prevent illness from bacteria: keep eggs refrigerated, cook eggs until yolks are firm, and cook foods containing eggs thoroughly. ”

Eggs that have been treated to destroy Salmonella–by in-shell pasteurization, for example–are not required to carry safe handling instructions, but the labeling will usually say that they have been treated.

Many foods become contaminated when prepared by people who don’t wash their hands thoroughly after using the toilet or changing a diaper. Infection also can occur if you touch something that is contaminated, including pets, especially birds and reptiles, and then put your fingers in your mouth.

Illness from Salmonella can be serious and is more dangerous for certain people

Older adults, infants, and people with weakened immune systems, such as those with HIV/AIDS, diabetes, or an organ transplant, may get a more serious illness that can even be life-threatening.

In most cases, illness lasts 4–7 days and people recover without antibiotic treatment. Possible signs and symptoms include:

  • Diarrhea.
  • Fever.
  • Abdominal cramps.
  • Nausea
  • Vomiting
  • Fever
  • Chills
  • Headache
  • Blood in the stool

Symptoms typically appear 6 to 48 hours after eating a contaminated food, though this period is sometimes much longer. Some people can have diarrhea many times a day for several days and the sick person may need to be hospitalized.

Signs and symptoms of salmonella infection generally last two to seven days. Diarrhea may last up to 10 days, although it may take several months before bowels return to normal.

A few varieties of salmonella bacteria result in typhoid fever, a sometimes deadly disease that is more common in developing countries.

What problems can salmonellosis cause during pregnancy ?

Salmonellosis can lead to health complications during pregnancy, including 3):

  • Dehydration
  • Bacteremia (bacteria in the blood). This can lead to problems, like meningitis. Meningitis is an infection that causes swelling in the brain and spinal cord.
  • Reactive arthritis (also called Reiter’s syndrome). This can cause swelling or pain in joints, like the knees, ankles and toes.
  • You can pass salmonellosis to your baby during pregnancy. If your baby is born with salmonellosis, she may have diarrhea and fever after birth. She also may develop meningitis.

Contact your doctor or healthcare provider if you have:

  • High fever (temperature over 101.5°F).
  • Diarrhea for more than 3 days that is not improving.
  • Bloody stools.
  • Prolonged vomiting that prevents you from keeping liquids down.
  • Signs of dehydration, such as:
  • Making very little urine.
  • Dry mouth and throat.
  • Dizziness when standing up.

How you can reduce your chance of getting a Salmonella infection ?

  • Consider buying and using pasteurized eggs and egg products, which are widely available.
  • Keep eggs refrigerated at 40°F (4°C) or colder at all times. Only buy eggs from stores and suppliers that keep them refrigerated.
  • Discard cracked or dirty eggs.
  • Cook eggs until both the yolk and white are firm. Egg dishes should be cooked to an internal temperature of 160°F (71°C) or hotter.
  • Make sure that foods that contain raw or lightly cooked eggs, such as hollandaise sauce, Caesar salad dressing, and tiramisu, are made only with pasteurized eggs.
  • Eat or refrigerate eggs and foods containing eggs promptly after cooking. Do not keep eggs or foods made with eggs warm or at room temperature for more than 2 hours, or 1 hour if the temperature is 90°F or hotter.
  • Wash hands and items that came into contact with raw eggs—including, counter tops, utensils, dishes, and cutting boards—with soap and water.
  • Cook eggs thoroughly. Raw and undercooked eggs contain Salmonella bacteria that can make you sick.

Serving

Follow these serving guidelines for eggs and egg dishes.

  • Serve cooked eggs (such as hard-boiled eggs and fried eggs) and egg-containing foods (such as such as quiches and soufflés) immediately after cooking. Cooked eggs and egg dishes may be refrigerated for serving later but should be thoroughly reheated to 165° F before serving.
  • Never leave cooked eggs or egg dishes out of the refrigerator for more than 2 hours or for more than 1 hour when temperatures are above 90° F. Bacteria that can cause illness grow quickly at warm temperatures (between 40° F and 140° F).
  • For party planning, keep hot egg dishes hot and cold egg dishes cold:
    • Keep egg dishes refrigerated until time to serve.
    • Serve small platters of reheated egg dishes at a time to ensure the food stays at the proper temperature. Replenish as needed, or at least every 2 hours.
    • Keep cold egg dishes on ice if they are going to stay out longer than 2 hours.

Antinutritional Factors

Egg components are also reported to be highly digestible although a small amount of egg proteins is not assimilated 4), especially when egg is consumed as a raw ingredient 5). The higher digestibility of cooked egg proteins results from structural protein denaturation induced by heating, thereby facilitating hydrolytic action of digestive enzymes. However, although the assimilation of egg protein is facilitated by heat-pretreatment and at a high level (91–94% for cooked egg-white proteins), it remains partly incomplete. It is noteworthy that major proteins, essentially egg-white proteins such as the proteinase inhibitor ovomucoid, and major egg-white ovalbumin resist thermal heating 6).

As mentioned above, major proteins of egg include protease inhibitors that may delay the proper degradation of egg proteins by inhibiting digestive enzymes including pepsin, trypsin, and chymotrypsin. Egg white is a major source of ovostatin, ovomucoid, ovoinhibitor, and cystatin 7). Moreover, some of these molecules (ovoinhibitor, ovomucoid, cystatin) possess many disulfide bonds that are likely to confer moderate resistance to denaturation by proteases and gastric juices. Some of these antinutritional factors may be partly denatured by heat 8) during the process of cooking, thus facilitating protein access to digestive proteases. Moreover, some vitamin-binding proteins highly concentrated in egg may also limit some vitamin access—avidin that binds vitamin B12 (biotin) exhibits the highest known affinity in nature between a ligand and a protein 9). The bioavailability of biotin for consumers may be compromised by the tight complex formed between avidin and its bound vitamin B8.

Raw egg nutrition facts

how much cholesterol in eggs

The components of an egg weighing 60 grams are made up as follows:

  • Yolk (29%) – 17.4 g
  • White (61.5%) – 36.9 g
  • Shell (9.5%) – 5.6 g

Egg albumen or white. The albumen of the egg is composed of the outer thin albumen and the inner firm or thick albumen. The outer thin albumen spreads around the inner firm albumen. The inner firm albumen in high quality eggs stands higher and spreads less than the outer thin albumen.

Yolk. The yolk is almost spherical and is surrounded by a colorless membrane. The color of the yolk varies with the type of feed given to the laying hen. If the laying hen is fed yellow corn, alfalfa meal and fresh grass provide good pigment sources for a normal yellowish-orange yolk. The color of the yolk does not affect the nutritional content.

Eggs contain the highest quality protein and are often used as a standard to measure the quality of other protein sources. A single large egg provides 12 percent of the daily requirement of protein for 70 calories 10). Eggs also have the highest biological value of any protein, meaning that the essential amino acids they provide are used very efficiently by the body. Eggs also contain varying amounts of vitamins A, D, E, K, B6, B12, folate, and a variety of minerals (particularly riboflavin, phosphorus, and iron). Because eggs are very easy to digest, they are frequently included in therapeutic diets.

  • But the full health benefits of eggs can only be realized if you store them properly — in the refrigerator — and cook them thoroughly to kill any potential bacteria.

The egg is a powerhouse of disease-fighting nutrients like lutein and zeaxanthin. These carotenoids may reduce the risk of age-related macular degeneration, the leading cause of blindness in older adults. And brain development and memory may be enhanced by the choline content of eggs.

The egg yolk makes up just over one third of an egg. It provides three-fourths of the calories, all of the fat-soluble vitamins (A, D, E, and K), and all of the choline, lutein, and zeaxanthin. The yolk also provides most of the phosphorus, iron, and folate and almost half of the protein and riboflavin. The white (albumen) provides more than half of the total protein and riboflavin. Hens given a high protein feed lay eggs with 1 to 2% more protein than in the other group 11). Choline, an essential nutrient, is shown to be important for proper brain development in the fetus and newborn and may play a role in memory function throughout life and into old age. Lutein and zeaxanthin may prevent macular degeneration, a leading cause of blindness in the elderly in the U.S. One large egg (50 grams) provides the daily requirements of 27% selenium, 25% vitamin B12, 23% choline, 15% riboflavin, 13% protein, 11% phosphorus, 9% vitamin D 12). Though these nutrients are present only in small amounts in eggs, research shows that they may be more bioavailable, or absorbed and utilized by the body, when obtained from egg yolk than from richer sources.

While it’s true that just one egg yolk has about 200 mg of cholesterol—making it one of the richest sources of dietary cholesterol—eggs also contain additional nutrients that may help lower the risk for heart disease. In addition, the moderate amount of fat in an egg, about 4.5 grams, is mostly monounsaturated and polyunsaturated fat, a fat that you need to be healthy. An egg contains only about 1.65 g of saturated fat and no trans fat. It’s also crucial to distinguish between dietary cholesterol and cholesterol in the blood, which are only weakly related. The focus on dietary cholesterol alone was de-emphasized as more attention was placed on the influence of saturated and trans fat on blood cholesterol. Accordingly, the Dietary Guidelines for Americans 2015 removed the prior recommendation to limit consumption of dietary cholesterol to 300 mg per day 13).

Brown eggs are not more nutritious than white. The color and size of an egg are determined by the breed of hen, which can produce white, cream, brown, blue, green or speckled eggs. The color of the yolk is also not reflective of nutritional value but the type of poultry feed.

As part of a healthy balanced diet you can eat up to 6 eggs each week without increasing your risk of heart disease.

Chicken eggs are high in cholesterol, but the effect of egg consumption on blood cholesterol is minimal when compared with the effect of trans fats and saturated fats. According to the U.S. Department of Agriculture, one large egg has about 186 mg milligrams (mg) of cholesterol — all of which is found in the yolk.

According to the U.S. Department of Agriculture, one large egg has about 186 mg milligrams (mg) of cholesterol — all of which is found in the yolk.

When deciding whether to include eggs in your diet, consider the recommended daily limits on cholesterol in your food:

  • If you are healthy, consume no more than 300 mg of cholesterol a day.
  • If you have diabetes, high cholesterol or cardiovascular disease, limit the daily cholesterol intake to no more than 200 mg a day (<200 mg/ day).

If you like eggs but don’t want the extra cholesterol, use only the egg whites. Egg whites contain no cholesterol. You may also use cholesterol-free egg substitutes, which are made with egg whites.

Some people are more sensitive to eating cholesterol in their diet and its effect on their blood cholesterol level. This means that when they eat food containing cholesterol, their LDL (bad) cholesterol levels rise more than other people.

People who have difficulty controlling their total and LDL “bad” cholesterol may want to be cautious about eating egg yolks and instead choose foods made with egg whites. The same is true for people with diabetes. In studies including the Nurses’ Health Study and Health Professionals Follow-up Study, heart disease risk was increased among men and women with diabetes who ate one or more eggs a day 14), 15). For people who have diabetes and heart disease, it may be best to limit egg consumption to no more than three yolks per week.

Furthermore, to truly assess eggs and heart health, we need to examine how they stack-up to foods you might choose in their place—the classic nutrition substitution analysis.

Using some common breakfast options as an example:

  • While eggs may be a much better choice than sugary, refined grain-based options like sweetened breakfast cereals, pancakes with syrup, muffins, or bagels, they may fall short of other options. A bowl of steel-cut oats with nuts and berries, for example, will be a much better choice for heart health than an egg-centric breakfast. Consumption of whole grains and fruit predict lower risk of heart disease, and when it comes to protein, plant sources like nuts and seeds are related to lower cardiovascular and overall mortality, especially when compared to red meat or eggs 16).

The bottom line: while eggs may not be the optimal breakfast choice, they are certainly not the worst, falling somewhere in the middle on the spectrum food choice and heart disease risk. For those looking to eat a healthy diet, keeping intake of eggs moderate to low will be best for most, emphasizing plant-based protein options when possible.

Egg white nutrition facts

Egg white, also referred to as egg albumen, contains 56 percent of the whole egg’s total protein along with the majority of the egg’s niacin, riboflavin, choline, magnesium, potassium, sodium and sulfur 17). Fifteen grams of egg white protein contain 1341 mg of leucine, 837 mg of isoleucine, and 1096 mg of valine, and there is also an abundant source of branched amino acids and aromatic amino acids. It is well established that essential amino acids 18) stimulate skeletal muscle protein synthesis in animal and human models 19), 20), 21), 22). Recent data showed that leucine induces a maximal skeletal muscle protein anabolic response in young adults 23), which suggests that leucine-rich egg white protein intake might have an important effect on body mass increase.

Alone, egg whites are about 88 percent water, 10 percent protein and almost completely free of fat and cholesterol, making it a very attractive ingredient in today’s food formulating industry. In fact, egg whites are a high‐quality, nutrient dense food ingredient, as the protein in egg white has a very high biological value. It has also been shown to provide satiety and thus assist in weight loss diets 24).

Benefits of egg white

Protein intake is an important component of body building, and together with additional supplements (i.e., creatine and amino acids), is highly recommended for regular strength training. Long term, periodized resistance training (weights training) results in increases in skeletal muscle size and, ultimately, force generating capacity 25), 26). Sports nutrition scientists have attempted to increase training induced gains through a number of protocols, which generally attempt to augment and/or speed skeletal muscle regeneration. One such intervention has been to increase the provision of the branched chain amino acids, leucine, isoleucine, and valine, which make up more than one third of muscle protein 27). The branched chain amino acids are unique among the essential amino acids for their roles in protein metabolism 28), neural function 29), and blood glucose and insulin regulation 30). Moreover, Garlick and colleagues 31) have found that branched chain amino acids were able to stimulate skeletal muscle protein synthesis to the same degree as all 9 essential amino acids. Of the branched chain amino acids, only leucine was able to independently stimulate muscle protein synthesis 32). It is well known that vigorous exercise can induce a net negative protein balance in response to both endurance and resistance training 33). Norton and Layman proposed that consumption of branched chain amino acids, namely leucine, could turn individuals from a negative to a positive whole-body protein balance after intense exercise 34). In support, the consumption of a protein or essential amino acid complex that contains sufficient leucine has been shown to shift protein balance to a net positive state after intense exercise training 35). These findings led Norton and Wilson 36) to suggest that optimal protein intake per meal should be based on the leucine content of the protein consumed.

Early research indicates that 2-3 g, or up to 0.05 g/kg bodyweight, of leucine are required to maximize muscle protein synthesis 37), 38), 39). However once this threshold has been reached, a protein’s beneficial effects on muscle protein synthesis effectively plateaus. For example, consuming 40 grams of egg protein (4 grams of leucine) did not enhance muscle protein synthesis over 20 grams of egg protein (2 grams of leucine) 40).

Moore et al. 41) conducted a dose response study of an egg protein supplement comparing 0 g, 5 g, 10 g, 20 g, and 40 g of egg protein delivered after a bout of exercise. After consumption of the supplement, muscle protein synthesis rates were monitored for four hours. Their results suggested that muscle protein synthesis was maximally stimulated with 20 g of egg protein, which contains 1.7 g of leucine. It was also observed that at double that dose (40 g, 3.4 g of leucine), no significant differences in muscle protein synthesis occurred 42). Male collegiate athletes consume more protein than what is recommended by the American Dietetic Association 43). Bianco et al. 44) reported that 30.1% of male athletes use dietary supplements during training as a “way to gain muscle and strength”, and also showed that whey protein shakes (50.0%) supplemented with creatine and amino acids (48.3%) were the most frequent choices amongst users.

Several reports describe how whey protein and amino acid supplementation increases muscle protein synthesis at rest 45), 46) and after weights training 47).

However this small study involving 30 young Japanese female college athletes showed that egg white protein supplementation (15 grams egg white protein; 75 kcal) or carbohydrate supplementation (17.5 g maltodextrin, 78 kcal). At baseline and 8 weeks after the regimen, participants performed 1RM strength tests by leg curl (LC), leg extension (LE), squat, and bench press exercises. The result was after 8 weeks ofegg white protein supplementation did not change body lean mass or muscle strength between those who consume egg white protein or carbohydrate 48). The findings showed that daily supplementation of either carbohydrate or egg white protein resulted in increase in the lean muscle mass and 1-RM (1-repetition maximum) muscle strength.

egg-nutrition-facts

Table 1. Raw egg (whole egg – fresh) nutrition facts

Sources of Data

1Nutrient Data Laboratory, ARS, USDA National Food and Nutrient Analysis Program Wave 14e , 2010 Beltsville MD
2Nutrient Data Laboratory, ARS, USDA National Food and Nutrient Analysis Program Wave 6b , 2002 Beltsville MD
3A. Kingman Unpublished data. NIDR/NIH, 1984 , 1984 Unpublished data. NIDR/NIH, 1984.
4Nutrient Data Laboratory, ARS, USDA National Food and Nutrient Analysis Program Wave 5b , 2000 Beltsville MD
5Horn-Ross, P. L., Barnes, S., Lee, M., Coward, L., Mandel, E., Koo, J., John, E. M., and Smith, M. Assesing phytoestrogen exposure in epidemiologic studies: development of a database (United States). , 2000 Cancer Causes and Control 11 pp.289-298
6Pei et al. Isoflavone content of eggs sampled in the Beltsville, Maryland Area. , 2015 Unpublished data

Table 2. Raw egg white (fresh) nutrition facts

Sources of Data

1Nutrient Data Laboratory, ARS, USDA National Food and Nutrient Analysis Program Wave 6d , 2002 Beltsville MD
2Pei et al. Isoflavone content of eggs sampled in the Beltsville, Maryland Area. , 2015 Unpublished data

Table 3. Raw egg yolk (fresh) nutrition facts

Sources of Data

1Nutrient Data Laboratory, ARS, USDA National Food and Nutrient Analysis Program Wave 6d , 2002 Beltsville MD
2Pei et al. Isoflavone content of eggs sampled in the Beltsville, Maryland Area. , 2015 Unpublished data

When purchasing shell eggs, follow these guidelines:

  • Accept only clean, sound and odor-free eggs.
  • Purchase eggs according to grade and size desired and only in the quantity needed for one to two weeks.
  • Accept only eggs delivered under refrigeration at a temperature of 45° F or below. Transfer to refrigerated storage promptly.
  • Accept only eggs packed in snug-fitting fiberboard boxes to reduce breakage. Eggs are generally packed and purchased in 30-dozen cases or half cases of 15 dozen.
  • Consider size and grade in relation to use and price. Also, compare prices for different sizes of eggs of the same grade.
  • Check the grade of eggs delivered to you. Inspect the shells and then randomly break a few. These eggs should meet the guidelines for their given grades.
  • A quick test for freshness is to check if the raw egg in the shell sinks in a basin of water. Fresh eggs stay at the bottom of the bowl while older eggs float because of the large air cell that forms in its base.
  • If hard-boiling egg, it is best to use eggs a few days old. The fresher the egg, the more likely the white will stick to the shell.

How long do eggs last ?

The easiest way to maintain eggs at high quality is to store them in their original carton in the refrigerator as soon as possible after purchase. Cartons reduce water loss and protect flavours from other foods being absorbed into the eggs. Storing eggs loose, or in specially designed sections located on refrigerator doors is not recommended as this also exposes eggs to a greater risk of damage. The best conditions for egg storage are at a temperature of about – 1° C and relative humidity between 80 and 85 percent. At a temperature of 10° C, lower relative humidity is needed, between 75 and 80 percent. At all temperatures there is the risk of mould spoilage where the relative humidity is too high. Packaging materials that are too dry or are excessively moist and absorbent will also accentuate evaporation losses. Mould spores normally present on eggshells may, if sufficient time elapses, germinate and grow, penetrating the shell and causing spoilage. Generally this occurs only when eggs are in cold storage for several months or more under conditions of high humidity (above 85 percent). It can occur, however, at any temperature if the humidity is sufficiently high and the holding time long enough.

Fresh eggs can be kept refrigerated in their carton for 6 weeks from the date of pack. It is best to put eggs in the fridge as soon as you get them home, remember an egg ages 7 times quicker when left on the bench than when it is properly stored in the fridge. So to enjoy you fresh eggs for longer, store them in the fridge.

The main cause of spoilage by bacteria is the washing of dirty eggs before marketing. When the egg is washed, organisms from water – usually bacteria – can penetrate the shell. Once inside they multiply and eventually spoil the egg, causing green, black and red rots. Even when eggs become wet without any cleaning process, for example, by condensation after removal from refrigerated storage into a warm temperature, conditions may be favorable for the penetration of micro-organisms and rotting may follow. When eggs are kept dry, no such way is provided for bacteria to penetrate the shell.

References   [ + ]

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