Fresh eggs are a common food product obtained from domesticated hens (Gallus gallus domesticus) and are valued for their high nutritional content and versatility in cooking. Eggs can be used in a variety of culinary preparations, from main dishes to desserts, and are an excellent source of protein, vitamins, and minerals. They are available in different sizes and shell colors, depending on the breed of the hen.

Nutrition Facts

• Calories per 100g: Approximately 155 kcal
• Fat: 11g (of which saturated: 3g)
• Carbohydrates: 1g (of which sugars: 1g)
• Protein: 13g
• Cholesterol: Approximately 373 mg

Nutritional values can vary slightly based on the size of the egg and the method of raising the hens.

Chemical Composition and Structure
Fresh eggs are primarily composed of:

• Egg Whites (Albumen): About 60% of the total weight of the egg, rich in proteins and water.
• Yolk: Contains most of the nutrients, including fats, vitamins (such as A, D, E, and K), and minerals (like iron and phosphorus).
• Shell: Composed mainly of calcium carbonate, providing protection to the inner contents.

Physical Properties

• Appearance: The shell can be white or brown, while the interior consists of transparent egg whites and yellow yolks.
• Taste: The taste of eggs is mild and slightly creamy, with the yolk offering richness.
• Texture: Egg whites are liquid and viscous, while yolks are dense and creamy.

Production Process

1. Farming: Hens are raised on farms with access to fresh feed and water.
2. Collection: Eggs are collected manually or mechanically to ensure freshness.
3. Cleaning: Eggs are cleaned to remove dirt or debris without damaging the shell.
4. Packaging: Clean eggs are packaged in cartons for retail sale.

Applications

• Cooking: Used in omelets, frittatas, and as a base for main dishes.
• Baking: Essential in desserts, cakes, and creams, where they act as binders and leavening agents.
• Beverages: Used in preparations like zabaglione or cocktails.
• Nutrition: Utilized as a protein source in balanced diets.

Environmental and Safety Considerations

Fresh eggs are generally regarded as safe for consumption. However, it is important to ensure they come from sustainable farms where hens are treated ethically. 

It is advisable to store eggs in the refrigerator to maintain freshness and reduce the risk of contamination from Salmonella. 

Studies

On the intake of chicken eggs as regards its impact on human health, in recent decades, there are conflicting views.

Doubts focus on the cholesterol content and its potential role in cardio-metabolic outcomes.

A whole or boiled chicken egg contains about 15 micrograms of selenium and in addition iron, Vitamin B₂, B₁₂, D, E

It also contains lutein, a carotenoid that can be protective against diseases such as age-related macular degeneration (1) and choline, a cellular and nervous restructurer and anti-inflammatory.(2)

Recent studies have also shown that the egg, due to its vitamin D content, helps protect the eyes from cataracts and other degenerative diseases due to ageing.

On the other hand, health recommendations indicate that dietary cholesterol should be limited to less than 200 mg per day; a single large egg yolk contains about 275 mg of cholesterol (3), so taking even a single egg increases LDL cholesterol.

 The consumption of whole egg in the middle-aged and elderly population has long been discussed in the scientific literature.  The impact on the cardiovascular system with possibility of disease has been under observation for several years. However, this study considers that the intake of whole egg does not affect the risk of cardiovascular disease (4).

This study, on the other hand, considers that a high consumption of eggs is significantly associated with a higher risk of contracting incidental cardiovascular diseases (5).

Egg studies

References_________________________________________________________________________

(1) Chung HY, Rasmussen HM, Johnson EJ. Lutein bioavailability is higher from lutein-enriched eggs than from supplements and spinach in men. J Nutr. 2004 Aug;134(8):1887-93. 2004. 

Abstract. Lutein may be protective against diseases such as age-related macular degeneration (ARMD). At present, data regarding bioavailability of lutein from various sources are insufficient. Healthy men (n = 10) participated in an intervention study with a crossover design. After a 2-wk washout period during which they consumed a low-carotenoid diet, the men were administered 1 of 4 lutein doses (lutein supplement, lutein ester supplement, spinach, and lutein-enriched egg) for 9 d. All lutein doses provided 6 mg lutein except for the lutein ester dose, which provided 5.5 mg lutein equivalents. Serum samples were collected from fasting subjects on d -14, 1 (baseline), 2, 3, and 10 and analyzed for changes in lutein concentration. Triacylglycerol-rich lipoproteins (TRL) were separated from postprandial blood samples (0-24 h) after the first lutein dose and analyzed for lutein concentration. Subjects completed all 4 treatments of the study in random order. Results from repeated-measures 1-way ANOVA showed that the baseline and dose-adjusted lutein response in serum was significantly higher after egg consumption than after lutein, lutein ester, and spinach consumption on d 10. There was no significant difference in TRL response. In conclusion, the lutein bioavailability from egg is higher than that from other sources such as lutein, lutein ester supplements, and spinach. The lutein bioavailability from lutein, lutein ester supplements, and spinach did not differ. This finding may have implications for dietary recommendations that may decrease the risk of certain diseases, e.g., ARMD.

(2) Zeisel SH. Choline: critical role during fetal development and dietary requirements in adults. Annu Rev Nutr. 2006;26:229-50. 2006. 

Abstract. Choline is an essential nutrient needed for the structural integrity and signaling functions of cell membranes; for normal cholinergic neurotransmission; for normal muscle function; for lipid transport from liver; and it is the major source of methyl groups in the diet. Choline is critical during fetal development, when it influences stem cell proliferation and apoptosis, thereby altering brain and spinal cord structure and function and influencing risk for neural tube defects and lifelong memory function. Choline is derived not only from the diet, but from de novo synthesis as well. Though many foods contain choline, there is at least a twofold variation in dietary intake in humans. When deprived of dietary choline, most men and postmenopausal women developed signs of organ dysfunction (fatty liver or muscle damage), while less than half of premenopausal women developed such signs. Aside from gender differences, there is significant variation in the dietary requirement for choline that can be explained by very common genetic polymorphisms.

(3) Spence JD, Jenkins DJ, Davignon J. Dietary cholesterol and egg yolks: not for patients at risk of vascular disease. Can J Cardiol. 2010 Nov;26(9):e336-9. doi: 10.1016/s0828-282x(10)70456-6. PMID: 21076725; PMCID: PMC2989358.. 

Abstract. A widespread misconception has been developing among the Canadian public and among physicians. It is increasingly believed that consumption of dietary cholesterol and egg yolks is harmless. There are good reasons for long- standing recommendations that dietary cholesterol should be limited to less than 200 mg/day; a single large egg yolk contains approximately 275 mg of cholesterol (more than a day's worth of cholesterol). Although some studies showed no harm from consumption of eggs in healthy people, this outcome may have been due to lack of power to detect clinically relevant increases in a low-risk population. Moreover, the same studies showed that among participants who became diabetic during observation, consumption of one egg a day doubled their risk compared with less than one egg a week. Diet is not just about fasting cholesterol; it is mainly about the postprandial effects of cholesterol, saturated fats, oxidative stress and inflammation. A misplaced focus on fasting lipids obscures three key issues. Dietary cholesterol increases the susceptibility of low-density lipoprotein to oxidation, increases postprandial lipemia and potentiates the adverse effects of dietary saturated fat. Dietary cholesterol, including egg yolks, is harmful to the arteries. Patients at risk of cardiovascular disease should limit their intake of cholesterol. Stopping the consumption of egg yolks after a stroke or myocardial infarction would be like quitting smoking after a diagnosis of lung cancer: a necessary action, but late. The evidence presented in the current review suggests that the widespread perception among the public and health care professionals that dietary cholesterol is benign is misplaced, and that improved education is needed to correct this misconception.

(4) Wang MX, Wong CH, Kim JE. Impact of whole egg intake on blood pressure, lipids and lipoproteins in middle-aged and older population: A systematic review and meta-analysis of randomized controlled trials. Nutr Metab Cardiovasc Dis. 2019 Jul;29(7):653-664. doi: 10.1016/j.numecd.2019.04.004. 

(5) Zhong VW, Van Horn L, Cornelis MC, Wilkins JT, Ning H, Carnethon MR, Greenland P, Mentz RJ, Tucker KL, Zhao L, Norwood AF, Lloyd-Jones DM, Allen NB. Associations of Dietary Cholesterol or Egg Consumption With Incident Cardiovascular Disease and Mortality. JAMA. 2019 Mar 19;321(11):1081-1095. doi: 10.1001/jama.2019.1572. 

Abstract. Importance: Cholesterol is a common nutrient in the human diet and eggs are a major source of dietary cholesterol. Whether dietary cholesterol or egg consumption is associated with cardiovascular disease (CVD) and mortality remains controversial. Objective: To determine the associations of dietary cholesterol or egg consumption with incident CVD and all-cause mortality....Conclusions and relevance: Among US adults, higher consumption of dietary cholesterol or eggs was significantly associated with higher risk of incident CVD and all-cause mortality in a dose-response manner. These results should be considered in the development of dietary guidelines and updates.