Egg white vs Yolk - Health impact and Nutrition Comparison

Summary

Egg yolk is much higher in calories and most nutrients, including protein, fats, carbohydrates, vitamins A, D, E, and K, vitamins B9 and B12, as well as iron, phosphorus, calcium, and more. Egg whites are very high in protein while also being richer in vitamin B3, potassium, and magnesium.

Moderate consumption of eggs can provide substantial nutrients necessary for overall health; however, excessive intake may lead to detrimental effects, such as diabetes and cancer.

The choice between egg white vs. yolk entirely depends on the preferences and needs of the consumer.

Introduction

Egg whites and egg yolks serve separate, distinct purposes in nature. Because of this, they have very different nutritional profiles.

In this article, we will dive into their specific differences or similarities and see how they affect our health.

Egg yolk functions as the primary source of nutrients for the chicken embryo. Egg whites, on the other hand, primarily play a protective role for the embryo, being situated between the embryo and the hard eggshell while also providing additional nutrition. Egg white is also often called albumen, based on the predominant protein found in it.

Taste and Use

Because of the nutritional differences, yolk tastes richer than egg white. Egg white is often used to add airy texture and foam to a dish, while yolk can act as an emulsifier.

Egg white is often separated from the yolk to make meringue, macaroon, or egg white omelets.

Egg yolk can also be used on its own to make mayonnaise, custard, and hollandaise sauce.

Interestingly, egg whites have been used not only in the kitchen but also as a binding agent in photography, bookbinding, and wine-making, while yolk has been used in painting and microbiology.

Sizes

Naturally, different sizes of eggs contain different amounts of the same nutrients. The USDA has divided egg sizes into five groups (1).

• Small: 43g (1.5oz)
• Medium: 50g (1.75oz)
• Large: 57g (2oz)
• Extra-large: 64g (2.25oz)
• Jumbo: 71g (2.5oz)

Of this, egg white accounts for about 67% of the liquid weight, whereas yolk makes up the other 33% (2).

Nutrition

We know that yolk and egg white are both highly nutritious, but which one provides more macronutrients, minerals, and vitamins?

Macronutrients and Calories

Egg yolk is considerably denser in nutrients, containing only 52% water, whereas egg white consists of 88% water.

One average size of egg white is considered to be 33g, while an egg yolk’s serving size is equal to 17g.

Calories

Egg yolk alone is a very high-calorie food, containing 322 calories per 100g. However, the yolk is usually not consumed in those amounts. One serving size of yolk contains 55 calories.

Egg white has much fewer calories, with 52 calories in a hundred grams.

Protein

Egg white is a rare food that consists almost entirely of protein and water. Egg white is commonly referred to as albumen due to its main protein.

That being said, the egg yolk is richer in protein, being denser in nutrients overall. The yolk provides 5g more protein per 100g serving compared to egg white.

The protein found in yolk and egg white is highly nutritious, containing large amounts of all essential amino acids. Yolk protein is a little richer in most of these amino acids.

Fats

The yolk has rich fat content, while egg white contains only a negligible amount of fats.

The predominant fat type in egg yolk is monounsaturated fat, closely followed by saturated fat, leaving polyunsaturated fatty acids in the last place.

Egg yolk also contains large amounts of cholesterol. We will discuss the effects of this substance on our cardiovascular health in the “Health Impact” section.

One of the most important fats found in yolk is called lecithin. This fat is partially responsible for many health effects and physicochemical properties of egg yolk, including the yellow color.

Carbohydrates

Yolk also contains higher amounts of carbohydrates. However, both egg white and yolk do not contain fiber and are very low in sugars.

Vitamins

Egg yolk is much richer in all vitamins except for one. Egg white contains more vitamin B3.

Four vitamins can be found in the yolk that are completely absent in egg whites. These are vitamin A, vitamin E, vitamin D, and vitamin K. 

The reason for this difference is that these vitamins are all fat-soluble and cannot exist in the fat-free environment of egg whites.

Other vitamins that yolk is higher in include vitamins B1, B2, B5, B6, B12, and the folate form of vitamin B9.

Both egg white and yolk entirely lack vitamin C.

Vitamin Comparison

Vitamin comparison score is based on the number of vitamins by which one or the other food is richer. The "coverage" chart below show how much of the daily needs can be covered by 300 grams of the food

Egg white

1

:

10

Yolk

Contains more Vitamin B3 +337.5%

Contains more Vitamin A +∞%

Contains more Vitamin E +∞%

Contains more Vitamin D +∞%

Contains more Vitamin B1 +4300%

Contains more Vitamin B2 +20.3%

Contains more Vitamin B5 +1473.7%

Contains more Vitamin B6 +6900%

Contains more Folate +3550%

Contains more Vitamin B12 +2066.7%

Contains more Vitamin K +∞%

Egg white

Yolk

Contains more Vitamin B3 +337.5%

Contains more Vitamin A +∞%

Contains more Vitamin E +∞%

Contains more Vitamin D +∞%

Contains more Vitamin B1 +4300%

Contains more Vitamin B2 +20.3%

Contains more Vitamin B5 +1473.7%

Contains more Vitamin B6 +6900%

Contains more Folate +3550%

Contains more Vitamin B12 +2066.7%

Contains more Vitamin K +∞%

Minerals

Egg yolk is higher in almost all minerals as well. The yolk contains higher amounts of iron, phosphorus, calcium, selenium, zinc, copper, manganese, and choline. The yolk is also much lower in sodium.

Egg white, on the other hand, is richer in magnesium and potassium.

Mineral Comparison

Mineral comparison score is based on the number of minerals by which one or the other food is richer. The "coverage" chart below show how much of the daily needs can be covered by 300 grams of the food

Egg white

2

:

6

Yolk

Contains more Magnesium +120%

Contains more Potassium +49.5%

Contains more Calcium +1742.9%

Contains more Iron +3312.5%

Contains more Phosphorus +2500%

Contains less Sodium -71.1%

Contains more Zinc +7566.7%

Contains more Copper +234.8%

Egg white

Yolk

Contains more Magnesium +120%

Contains more Potassium +49.5%

Contains more Calcium +1742.9%

Contains more Iron +3312.5%

Contains more Phosphorus +2500%

Contains less Sodium -71.1%

Contains more Zinc +7566.7%

Contains more Copper +234.8%

Glycemic Index

Both egg white and yolk contain so few carbohydrates that measuring the glycemic index would be exceedingly difficult. For this reason, their glycemic index values are assumed to fall in the low category.

Eating egg white or yolk alone should not have much effect on your blood glucose levels (3).

Acidity

Egg white is a naturally alkaline food with a pH value ranging from 7.6 to 9.2. The egg white's alkaline properties increase as the egg ages (4).

On the other hand, egg yolk has a pH value ranging from 6 to 6.9, making it acidic. The acidity of egg yolk also increases during egg storage (4).

The acidity of the whole egg tends to be neutral.

Another way to look at the acidity of foods is the potential renal acid load (PRAL). The PRAL shows us how much base or acid the given food produces in our bodies.

The PRAL value for egg white has been calculated to be 2.1, making it acid-producing. Egg yolk has a higher acid-forming PRAL value of 18.1.

Weight Loss

Egg whites are much lower in calories, as well as all macronutrients, compared with the yolk. However, one serving of yolk, containing 55 calories, can also provide the body with many essential minerals and vitamins.

Eggs, overall, have been found to enhance weight loss when they are incorporated into energy-deficit diets (5). So even with the high-calorie yolk, they can be a great addition to a weight management diet.

It has been studied that dietary egg white protein reduces body fat mass in rats by accelerating certain liver functions (6).

The blood level of an enzyme called cholecystokinin increases after egg yolk consumption. This may be the reason for the property of whole eggs or egg yolk to induce greater satiety and reduce short-term food intake compared to other foods with the same amount of calories (7).

Egg white is the right choice between these two for low-calorie, low-carb, and low-fat diets.

Health Impact

As we can see, egg white and yolk are rich in different macronutrients, minerals, and vitamins. In this section, we will look into what that means for our health.

Health Benefits

Cardiovascular Health

We’ve all heard how cholesterol can be dangerous for our cardiovascular health. Egg white contains an insignificant level of fats, while the yolk is high in cholesterol. 

However, a moderate amount of cholesterol, consumed in a healthy diet, is not only harmless but also necessary for many functions of the organism (8).

Scientists have found that moderate egg or egg yolk consumption is not associated with an increased risk of cardiovascular disease or stroke among healthy individuals (9). But for people with already existing cardiovascular health issues in need of controlling their cholesterol levels, it is better to opt for egg whites only or reduce whole egg consumption (10).

Diabetes

Even though both egg white and yolk have very low glycemic indices, their consumption is not advised for people at risk of diabetes.

High levels of whole egg consumption have been found to have an association with increased risk of diabetes mellitus type 2, as well as heart disease risk for people with diabetes (11, 12).

Possible mechanisms for these effects are the oxidative and inflammatory effects of choline found in the yolk and slower carbohydrate absorption from chemicals found in egg whites (13).

In contrast to this, some studies found either inverse or no association between high egg consumption and diabetes (14, 15).

Downsides and Risks

Cancer

Quite a few studies have suggested a correlation between egg consumption and certain types of cancers.

One research, in particular, found high egg consumption to increase the risk of several cancers: oral cavity and pharynx, upper respiratory and digestive tracts, colorectal, lung, breast, prostate, and bladder (16).

Another study found that the agents causing lymphosarcomas and lung adenocarcinomas were present in both egg white and yolk, whereas mammary carcinogens were only found in egg yolk (17).

Allergy

Egg allergies are one of the most common allergies in the world, especially in children. People are more often allergic to egg whites than yolk, as most allergenic egg proteins are found in egg white (18).

Egg allergy symptoms can range from mild rash, indigestion, and coughing to an anaphylactic reaction (19).

Biotin deficiency

Consuming raw egg white for a prolonged period of time can cause biotin deficiency. 

A protein present in egg white, avidin, tightly binds biotin, also known as vitamin B7, making it unavailable for intestinal absorption. This problem does not occur with cooked eggs, as high heat changes the structure of avidin (20).

Salmonella poisoning

Even though only 1 in every 20000 eggs may be contaminated with Salmonella bacterium, eating raw eggs may still be hazardous for health (21). Thoroughly cooking eggs kills the bacteria.

Salmonella poisoning symptoms may include nausea, vomiting, diarrhea, fever, and stomach cramps. This is particularly dangerous for children, pregnant women, and elderly people.

References

1. https://www.ams.usda.gov/sites/default/files/media/Shell_Egg_Standard%5B1%5D.pdf
2. https://afs.ca.uky.edu/files/1-composition_of_the_egg.pdf
3. https://glycemicindex.com/faqs/
4. https://www.incredibleegg.org/professionals/manufacturers/real-egg-functionality/ph-stability
5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2755181/
6. https://pubmed.ncbi.nlm.nih.gov/28980893/
7. https://pubmed.ncbi.nlm.nih.gov/8773735/
8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6682969/
9. https://jamanetwork.com/journals/jama/fullarticle/189529
10. https://www.hsph.harvard.edu/nutritionsource/food-features/eggs/
11. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2628696/
12. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3683816/
13. https://www.pcrm.org/news/health-nutrition/egg-consumption-increases-risk-diabetes
14. https://pubmed.ncbi.nlm.nih.gov/25832339/
15. https://pubmed.ncbi.nlm.nih.gov/26404366/
16. https://pubmed.ncbi.nlm.nih.gov/20104980/
17. https://journals.sagepub.com/doi/abs/10.3181/00379727-112-28254
18. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3069662/
19. https://acaai.org/allergies/types-allergies/food-allergy/types-food-allergy/egg-allergy
20. https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/biotin-deficiency
21. https://extension.umn.edu/preserving-and-preparing/handling-eggs-prevent-salmonella