Are eggs a good source of protein? Without any doubt, they are perfect for those who follow an ovo-lacto-vegetarian diet. In fact, they will provide the necessary protein so that our body can work efficiently.
That is why we have written this in-depth article to develop some of the aspects that we need to take into account.
- 1. Composition of an egg
- 2. Nutritional properties of eggs
- 3. The egg white is an excellent food but, what about the yolk?
- 4. What are the properties and benefits of the Egg Yolk?
- 5. Color of the Yolk
- 6. Nutritional value of the Egg Yolk
- 7. Protein content of the Egg Yolk
- 8. What are the vitamins and minerals from the Egg Yolk?
- 9. Eggs, Essential for Athletes
- 10. Egg Protein
- 11. Types of Egg
- 12. How to cook an egg?
- 13. Egg Protein Supplements
- 14. Best Recipes with Egg
- 15. Does egg increase the cholesterol?
- 16. How do you know if an egg is fresh?
- 17. How many eggs should I eat per week?
- 18. Absorption of raw egg protein vs Absorption of cooked egg protein
- 19. How is the egg protein absorbed?
- 20. What do the experts think about egg protein?
- 21. Bibliography
Composition of an egg
It is a very healthy food with a high protein content that is very important for athletes. In fact, it is low in calories and provides vitamins. For example, the B complex, vitamin B1, B3, B12, folic acid and biotin. All of them are closely related to the brain and energy production.
Moreover, it is rich in minerals with antioxidant properties: selenium, zinc (key for an adequate oxidative balance), phosphorus and iron. It also provides carotenes.
Finally, we need to emphasize its versatility. You can cook it in many different ways and combine it with many products.
Nutritional properties of eggs
If we take an egg that weighs 60 grams as a reference, 7.5g are protein. Therefore, a single egg will provide a 10% of the daily protein requirements of an adult that weighs 75kg.
However, around a 60% of the protein from eggs is found in the white. On top of that, this product provides many other excellent nutrients for our health. For instance, minerals like calcium, iron, zinc, sodium and copper, as well as vitamin B12, niacin, folic acid, and riboflavin.
We also feel the need debunk the myth that eggs fatten you up. In fact, an egg like the one we previously described will hardly provide a total of 72 calories.
The problem lies in the way we cook it since we usually fry it with a lot of oil.
The egg white is an excellent food but, what about the yolk?
The yolk itself has a higher nutritional value than the white. However, it also contains all the fats which, when metabolized, will become cholesterol in the body. Although they are far less harmful than saturated fats.
On the other hand, we have also set out to debunk another myth that you have probably heard. Basically, some say that eating raw egg is not healthy or that it is necessary to remove the yolk first.
The yolk of an egg makes up around a 34% of the liquid weight of the egg. It contains all the fat from the egg and slightly less than half the protein. The yolk of a big egg contains around 55 calories.
Aside from niacin and riboflavin, the yolk contains more vitamins than the white, including vitamins B6 and B12, folic acid, pantothenic acid, and thiamine.
All vitamins A, D, E, and K from the egg are in the yolk
Egg yolks are one of the few foods that naturally contain vitamin D. In addition, the yolk contains more calcium, copper, iron, manganese, phosphorus, selenium, and zinc than the white.
What are the properties and benefits of the Egg Yolk?
When we talk about a healthy and balanced diet we mean the following: a diet that includes all the foods (including eggs) from nature in quantities and percentages adapted to each person. This also includes macro and micro-nutrients: protein, fat, carbohydrates, vitamins and minerals.
Eggs can be part of a balanced diet due to their properties and benefits for our health. In fact, they are regarded as one of the most nutritionally dense foods.
They only contain 70 calories on average (like a fruit). Although the egg white barely contains any fat and it is a little higher in protein than the yolk. Approximately, the total fat content of an egg goes from 4 to 4.5g, of which 1.5g are saturated and the rest unsaturated. These are mainly monounsaturated fats, which are beneficial for the health of the organism.
The yolk is where the nutrients are stored: vitamins, minerals and other elements.
Color of the Yolk
The color of the yolk depends on the way the hen is fed. If a hen eats many pigments from yellow-orange plants called xanthophylls, they will transfer to the egg yolk.
Hens fed with mashed yellow corn or alfalfa flour lay eggs with medium yellow yolks. While those that eat wheat or barley produce a lighter color.
A “colorless” diet from white corn flour results in almost colorless yolks. Natural yellow-orange substances, such as marigold petals, can help to improve the color of the yolk. Artificial additives are absolutely forbidden.
Nutritional value of the Egg Yolk
The average weight of a big egg yolk is around 17g, so the nutritional value of a yolk would be:
|of which saturated||1.6g|
|of which monounsaturated||1.9g|
|of which polyunsaturated||0.72g|
Protein content of the Egg Yolk
A proper protein supply in the diet should include all the essential amino acids that your body needs on a daily basis. This is mainly due to the fact that we cannot synthesize these elements. Fortunately, egg has all of them: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.
These amino acids are present in amounts that closely match the ones that the human body needs. That is why egg is often use as reference to measure the protein content of food
What are the vitamins and minerals from the Egg Yolk?
This product has traditionally been taken away from balanced diets due to its association with cholesterol. However, its nutritional properties provide many benefits for the body as long as we control its consumption.
The egg yolk is a powerful source of vitamins for our health, such as:
- A, which is closely related to our sight and the immune system.
- E, which produces an antioxidant effect on the body.
- D, which protects the immune system.
- H or Biotin, which supports the healthy growth of the skin and hair.
- Folic acid, a key element for our growth, as well as before and during a pregnancy.
- B12, a source of energy for the body and the nervous system.
- B6, the most important coenzyme in the metabolism of amino acids.
- B2, which contributes to the metabolism of protein and fat, apart from supporting the formation of red blood cells and antibodies.
- B1, which helps to produce energy, strengthen the heart and stimulate the muscle growth.
Egg yolks are one of the few foods that naturally contain vitamin D. Apart from vitamins, the yolk also provides an excellent source of phosphorus, potassium and magnesium.
- It contains other substances called choline and inositol (the white has only traces). Both are involved in the development of the memory during the embryonic stage. In addition, eggs are one of the most important foods for the functioning of all cells.
- They also contain two important antioxidants: lutein and zeaxanthin. Above all, they support our visual health by preventing macular degeneration and cataracts, supporting the effects of vitamin A.
Eggs, Essential for Athletes
Eggs are a source of nutrients for athletes
There are not many other foods that gather such a variety of nutrients, apart from a proper protein supply. However, there are many athletes who are somehow reluctant to eat egg yolk due to its saturated fat content. But the truth is that there is not better way to improve the diet of athletes both in terms of calories and nutrients. Sometimes, we forget that there has to be a balance between omega 3 and omega 6 when taking “healthy fat” such as polyunsaturated fats. In fact, this is a very important factor when it comes to avoiding certain disorders.
Saturated fat fulfils important hormonal functions. Let’s not forget that this type of fat and cholesterol are two conditioning factors for the synthesis and production of testosterone.
An egg has several types of protein:
Ovotransferrin is a type of protein known as metalloprotein which binds to iron. It has antimicrobial properties and makes up more than a 10% of the protein content. Like serum transferrin, ovotransferrin is also similar to lactoferrin from milk in terms of itsstructure and function.
Ovomucin, another type of glycoprotein, makes up less than a 5% of egg white protein. Above all, it is responsible for its gelatinous texture.
Types of Egg
|Egg Size||Protein Content|
|S (less than 40g)||4.9g|
|M (between 40-50g)||5.5g|
|L (between 50-65g)||6.5g|
|XL (up to 70g)||7g|
|Jumbo (more than 70g)||8.5g|
Egg size and protein content (approximate value)
How to cook an egg?
Although fried egg is one of the most common ways to cook it, mainly because it is much more appetizing and tasty, it is not healthiest because frying it adds increases its fat content.
One way to cook it that is healthier and easier to digest than the first one is to make an omelette or scrambled eggs. The dish still feels tasty but it needs less oil and, therefore, less fat.
Boiled eggs are another very healthy way to add this food to our diet and to make a delicious Post-workout salad, for example.
Egg Protein Supplements
Taking egg protein supplements is a way to increase the daily protein supply and meet our protein requirements. A good choice would be using egg protein powder to combine it with other proteins such as whey. Consequently, we will obtain a time released protein, because in terms of absorption, egg protein would be “average”, while whey have a faster rate.
Egg white powder is a very interesting resource. Particularly because they have a longer expiry date.
Best Recipes with Egg
Eggs play an important role in the kitchen, since they are one of the ingredients that can be found in any home. Including a good protein supply in our diet has never been easier.
Some of the best recipes are:
You just have to whisk some eggs and cook them. This recipe provides way more nutrients than many commercial products.
Scrambled eggs for breakfast is one of the best ways of starting the day off
One of my favorite breakfasts without getting rid of the yolk. Most people tend to make pancakes just with the egg whites. The white only provides protein, while the micronutrients and a good part of the protein and fat will end up in the trash… Eggs are extremely versatile when it comes to cooking pancakes: we can use oat or rice flour, gluten-free recipes, sweet potato, carrot, fresh cheese, vegetables, protein powder or whey…
Boiled Eggs and Avocado Salad
It is one of my favorite combinations, since I eat salads almost every day, specially during the summer. Avocado has an excellent nutritional value. So even though it regarded as a very caloric fruit, it has other properties for our health.
Salad made with Boiled Eggs, Avocado and Tomato on Spinach leaves
Spanish (with or without onion) or French Omelette is a very easy meal that will fit in any type of diet. Personally, I like stuffing it with avocado and tomato…
If we are still not sure about fried eggs, which is a good recipe as long as we eat it moderately, we can try a quite satisfactory alternative: grilled eggs. This recipe is quite versatile since you can add it to a sandwich, as a side dish…
Does egg increase the cholesterol?
Our point of view has changed regarding the connection between egg and cholesterol, which is one of the most popular food myths. This is due to the fact that the relation between saturated and unsaturated fats is the main factor that increases the cholesterol, instead of the intake of cholesterol, as it was previously thought.
However, there are other factors, like stress, that can increase the endogenous production of cholesterol, even if we follow a low cholesterol diet. Smoking, a lack of physical exercise or obesity can also increase the fat and cholesterol levels.
That is why those who tend to produce a lot of cholesterol should change their lifestyle: do more exercise, eat less fat and more fruit, less sugars, quit smoking, and drink moderately.
Stop eating egg is NOT the solution!
How do you know if an egg is fresh?
To know if an egg is fresh without breaking it, we only have to put it inside a glass of water and see:
- If the egg sinks quickly and stays at the bottom: The egg is fresh.
- But, if the egg sinks more or less quickly and stays at the bottom: This means that the egg is good, but not as fresh.
- If the egg sinks little by little and remains standing (at the bottom): It means that the egg is about to become bad although it may still be edible.
- If the egg neither sinks nor goes to the bottom: It means that the egg is bad. There are other sources that claim that it is still edible, so it is up to you to decide.
- But, if the egg floats: It means it is bad. When organic matter rots it produces gases, which is the reason why the egg floats.
How many eggs should I eat per week?
In general, there is not a limit for the amount of eggs you can eat per week.
You can eat 1, 2, 3, half a dozen or up to 12 a week. This has actually been proven by Dr. Nick Fuller from the Boden Institute for Obesity, Nutrition, Exercise and Eating Disorders at the University of Sydney. In his clinical trial, he revealed that eating up to 12 eggs a week does not increase the risk of heart problems in those who suffer type 2 diabetes.
Dr Fuller stated that “although eggs themselves are high in cholesterol and people with type 2 diabetes tend to have higher levels of low-density lipoprotein (LDL) or “bad cholesterol”, this study supports existing research that shows how eating eggs has a minimal effect on the blood cholesterol levels in people who eat eggs”.
However, some people may have to reduce or limit their consumption according to medical advice.
This is why we should not avoid eating eggs unless there is a reasonable cause, since we would be missing many nutrients.
Absorption of raw egg protein vs Absorption of cooked egg protein
It is crucial to understand that raw egg white cannot be digested by our body at all. In fact, it is not advisable to eat it this way due to its taste since it is quite unpleasant and it can also be harmful for health, since it can be infected with salmonella.
The main proteins found in egg whites are Ovoalbumin and Ovotransferrin and their structures are long chains of amino acids which have a sturdy or elongated form when they are raw. This means that it is impossible for our digestive system to break them down and absorb their amino acids.
But also, the raw egg whites contain Ovomucoids and Ovoinhibitors that block the enzymes that are in charge of digesting the protein that we eat. These enzymes are involved in the digestion of protein by breaking the peptide bonds that keep the long amino acid chains together.
Solution: denature the protein
We need to denature egg white protein so that our body will be able to absorb it. This process changes its structure but its aminogram will not affected. This means that a denatured protein does not lose its properties, the only thing that changes is the fact that it is partially digested because some of its bonds have been destroyed to improve its absorption. This process does not damage the protein, rather, it helps the body with its absorption.
Denatured proteins are hydrolyzates which have broken peptide bonds, so that the amino acids are much easier to absorb
How is the egg protein absorbed?
If we want to absorb a 100% of the amino acids from egg protein, we mainly have two choices:
Mechanical or physical action
When we whisk the egg white until it becomes stiff we change the structure of the egg protein so that it can be easier to digest by the organism. However, whisking is not enough to avoid salmonella or the effect of the ovomucoids and ovoinhibitors.
Let’s not forget that even though the protein is physically denatured, the bacteria present in raw egg are still there. Therefore, the best choice would be using pasteurized egg whites
Without any doubt, the best way to denature egg protein is through heat. The kinetic energy caused by a higher temperature will enhance the vibration of the molecules that make up the protein. Consequently, it will break the bonds, keeping the amino acids intact.
If you heat a protein to 56ºC, the non-absorbable protein from the egg white are denatured. However, you have to cook them at 80ºC if you want to absorb them completely (a 94%).
Denaturing the protein from egg white like ovalbumin, ovotransferrin, ovoglobulins, etc, is just a process that involves transforming long amino acid chains that are found raw in some kind of bubbles or protein globules so that we can absorb them.
What do the experts think about egg protein?
1. Egg protein supports the immune system
Several studies conducted on the field of orthomolecular medicine have proven that the amount of sulfur amino acids from egg protein, like methionine and cysteine, plays an important role in the functioning of the immune system.
2. Egg protein improves the formation and growth of the muscles
A Canadian study has proven that 20 grams of egg protein stimulates the post-workout muscle growth. At the same time, it buffers the loss of muscle mass and shortens its regeneration.
3. Egg protein does not have side effects or interactions with medicines
Taking egg protein is completely as long as we follow the recommended dose. However, you should consult your doctor before taking egg protein if you have suffered renal or liver damage, or if you are pregnant or lactating.
- Chang C., Lahti T., Tanaka T., Nickerson MT. (2018). Egg proteins: fractionation, bioactive peptides and allergenicity
- Kritchevsky SB.(2004). A review of scientific research and recommendations regarding eggs
- Qureshi AI., Suri FK., Ahmed S., Nasar A., Divani AA., Kirmani JF. (2007). Regular egg consumption does not increase the risk of stroke and cardiovascular diseases
- Scrafford CG., Tran NL., Barraj LM., Mink PJ. (2011). Egg consumption and CHD and stroke mortality: a prospective study of US adults
- North Caroline Egg Association. Yolks VS Whites
- Van Vliet S., Shy EL., Abou Sawan S., Beals JW., West DW., Skinner SK., Ulanov AV., Li Z., Paluska SA., Parsons CM., Moore DR., Burd NA.(2017). Consumption of whole eggs promotes greater stimulation of postexercise muscle protein synthesis than consumption of isonitrogenous amounts of egg whites in young men
- Kritchevsky SB., Kritchevsky D. (2000). Egg consumption and coronary heart disease: an epidemiologic overview
- Larsson SC., Åkesson A., Wolk A. (2015). Egg consumption and risk of heart failure, myocardial infarction, and stroke: results from 2 prospective cohorts
- The great myths of nutrition