The Nutritional Powerhouse: Eggs and their Positive Impact on Human Health

World Egg Day is an opportune time to celebrate the incredible nutritional value of eggs and their positive contribution to human health. Eggs have been a staple food in many cultures for centuries and for a good reason. They are a rich source of essential nutrients, including high-quality proteins, vitamins, carotenoids, minerals, and healthy fatty acids.

1. Introduction

Eggs are renowned for their exceptional nutritional value, including 12 of the 13 essential vitamins, except vitamin C. The vitamins contained in eggs play a crucial role as essential nutrients for both humans and poultry.

A robust immune system is vital as the first line of defense against pathogens for both humans and poultry. In laying hens, vitamins A, B₆, B₁₂, C, D, E, and folate are particularly significant in supporting optimal immune system functioning. Providing these hens with optimum nutrition is key not only for bolstering and maintaining their immunity but also for preserving the nutritional value of the eggs. Often referred to as "nature's first food," eggs are backed by mounting evidence highlighting their nutritional benefits for children and women during pregnancy and childbirth. The unique composition of eggs, with their rich matrix of macronutrients, micronutrients, and immune factors, ensures they contain most of the essential nutrients required by the body, promoting growth, and potentially aiding in child development. As quoted by Lutter et al., the potential of a simple egg to improve maternal and child nutrition is significant.

By consuming two eggs daily, individuals can obtain approximately 40% of the Recommended Daily Allowance of biotin, 30% of vitamins A and B₂, 20% of vitamins D and E, and 15% of folate. The relationship between vitamin levels in layer feed and those in eggs has been the subject of studies since the 1990s. The vitamin content in eggs can vary greatly depending on the health condition of the chickens and the presence or absence of stress related to their feeding environment, on top of vitamin levels and the quality of vitamins in the diet. Thus, ensuring the health of hens through proper nutrition is essential for producing nutritionally enriched eggs, thereby providing evidence that these eggs come from only healthy hens.

Vitamins can be broadly classified into fat-soluble vitamins (A, D, E, and K) and water-soluble vitamins (B₁, B₂, B₆, and B₁₂, niacin, folate, biotin, and pantothenic acid). Generally, fat-soluble vitamins are more readily transferred to eggs, as water-soluble vitamins tend to function as coenzymes in the metabolic and maintenance processes of the body.

dsm-firmenich offers guidelines for optimal vitamin balances, taking into account the health, animal welfare, and productivity of animals. Additionally, eggs produced following Optimum Vitamin Nutrition (OVN™) level vitamins in feed exhibit notably increased levels of vitamin D (150%), vitamin E (200%), folic acid, and biotin (60%) compared to eggs from common layer feeds. Most vitamins accumulate in the egg yolk, although some levels of vitamin B₂, B₁₂, niacin, and pantothenic acid can also be found in the egg white.

In conclusion, eggs serve as a nutrient powerhouse, offering a range of essential vitamins that contribute significantly to overall health and well-being. Ensuring proper nutrition for laying hens translates to nutritionally enriched eggs, promoting both the health of consumers and the sustainability of egg production.

2. Nutritional Composition of Eggs

2.1 Protein

One of the most remarkable attributes of eggs is their protein content and quality. They are considered a complete protein source, meaning they contain all nine essential amino acids required by the human body. A single large egg typically provides around 6 grams of protein, making them an excellent dietary choice for promoting muscle growth, repair, and overall body maintenance. Protein coming from cooked eggs are practically 100% digestible. Care should be taken when eating raw eggs because the protein digestibility will be below 50%.

2.2 Vitamins

Eggs are a rich source of various vitamins, including:

Vitamin A:

Vitamin A is vital for growth, immunity, reproduction, vision, skin health, and mucosal integrity; its deficiency leads to disorders such as blindness, poor growth, weakened immunity, and epithelial tissue issues. Vitamin A enriched eggs often contain 200% or more of vitamin A compared with regular eggs. The transfer rate falls into a high class of vitamins, with more than 50% accumulating in egg yolk. It does not accumulate in the egg white.

Vitamin D:

Vitamin D plays a fundamental role in maintaining calcium and phosphorus balance within the body, influencing intestinal absorption, bone health, kidney function, immune system modulation, and muscular cell growth. Similarly, its metabolite 25OHD3, a major serum form, demonstrates more efficient absorption, quicker response for calcium homeostasis, and enhanced effects on immune system modulation and muscular cells, making it crucial for these functions. Both vitamin D3 and 25OHD3 deficiencies can lead to disorders such as rickets, osteomalacia, bone issues, compromised eggshell quality, reduced hatchability, slowed growth, and muscular weakness.

And the content of vitamin D in egg yolk is often variable but dependent on feed levels of the vitamin. Vitamin D enriched eggs tend to be approximately 400-500% higher than regular eggs. Vitamin D in eggs is classified into vitamin D3 and 25OHD3; and 25OHD3 is an active ingredient that has been gaining attention because it is also used as an index for measuring vitamin D levels in humans and animals, and it has been reported that its biological activity is five times that of vitamin D3. Approximately 500% more of the 25OHD3 supplement feed accumulates in egg yolk compared to regular eggs. Both vitamin D3 and 25OHD3 are accumulated only in egg yolk. The transfer rate to egg yolk is 10-30%.

Vitamin E:

Vitamin E, known as the most potent biological antioxidant, is a popular vitamin in nutritionally enriched eggs. It serves in immune system modulation, tissue protection, and fertility; deficiency can lead to disorders like muscular dystrophy, myopathy, reduced immune response, encephalomalacia, impaired fertility and hatchability, as well as meat quality defects in poultry. The amount of transfer to egg yolk varies greatly depending on how much of the antioxidant is required by the animal metabolism to maintain good health. OVN™ recommends increasing the dose of 5mg/kg diet for each 1% increase in fat level >3% in the diet. Vitamin E enriched eggs tend to contain 200-400% more than regular eggs. The transfer rate to egg yolk is 10-30%.

Vitamin K:

Vitamin K₃ serves as a pivotal coenzyme for blood clotting, coagulation, bone mineralization via calcium binding proteins, and protein synthesis. Deficiency results in prolonged clotting time, hemorrhages, anemia, bone disorders, compromised plumage quality, and increases the incidence of egg bloodspots in laying hens. Since vitamin K₃ mainly functions as a cofactor in the body, the transfer to eggs is also a low class among vitamins, and there are few cases of reinforced eggs worldwide because of the need for advanced analytical techniques.

Vitamin B group:

The B-vitamins are a group of water-soluble vitamins that play various essential roles in metabolism, energy production, and overall well-being. The B-group vitamins found in eggs include:

• Vitamin B₁ (thiamine) acts as a coenzyme in enzymatic reactions, supports carbohydrate metabolism, ATP production, nervous impulse transmission, and the transfer rate to eggs is less than 10%. OVN™ levels increased by 40-50% compared with regular eggs.
• Vitamin B₂ (riboflavin) aids in fat and protein metabolism, synthesizes flavin coenzymes for energy production, and maintains mucosa membranes and cellular antioxidants and is accumulated in both egg yolk and egg white. Very high vitamin B₂ levels result in yellowish egg white. Vitamin B₂ enriched eggs may contain around 20-30% more vitamin B2 than regular eggs.
• Vitamin B₃ (Niacin) plays as NAD and NADP, facilitates amino acid, fat, and carbohydrate metabolism while supporting skin, gastrointestinal, and nervous system health, resulting in an increase of 10-60% by OVN level supplementation. No Niacin enriched egg has been reported in the markets.
• Vitamin B₅ (Pantothenic Acid) found in CoA and ACP, aids in carbohydrate, fat, and protein metabolism, and contributes to fatty acid, phospholipid, and steroid hormone synthesis. Regular eggs contain 1-1.5 mg (per 100g of edible eggs) and increase in the range of 10-80% in some cases.
• Vitamin B₆ (pyridoxine) is essential for the metabolism of amino acids, fats, and carbohydrates, and is involved in DNA synthesis and niacin production, and the vitamin B₆ content in eggs does not increase much (10% or less) even when it is not so much required for body consumption or high inclusion level.
• Vitamin B₇ (Biotin) acts as a coenzyme in metabolism, maintaining blood glucose levels, and participating in fatty acid, nucleic acid, and protein synthesis and although there are no reported cases of enriched eggs, 30-60% increase was observed in higher levels and OVN levels compared with regular eggs.
• Vitamin B₉ (Folic Acid) acts as a coenzyme in nucleic acid and protein synthesis, stimulates hematopoiesis, while it has received attention as a vitamin important for the healthy growth of women and fetuses during pregnancy in recent years. For this reason, folate-enriched eggs using eggs are available on the market in some countries. Enriched eggs are increased by 20-120% compared to regular eggs.
• Vitamin B₁₂ (Cyanocobalamin) supports red blood cell synthesis, methionine metabolism, and acts as a coenzyme for nucleic acids and protein metabolism, but the transfer to eggs varies greatly depending on metabolic losses, so that reason vitamin B₁₂ enriched eggs can contain 40 to 180% compared to regular eggs. Deficiency disorders for each include neuropathies and muscle weakness (B₁), inflammation and paralysis (B₂), dermatitis and blood disorders (B₆), and anemia with feathering issues (B₁₂).

These B-vitamins work synergistically to support a range of bodily functions, including energy production, nervous system health, and the metabolism of macronutrients.

2.3 Carotenoids:

Carotenoids are naturally occurring compounds, of which about 800 species have been identified, and in recent years, it has become one of the nutrients with high antioxidant properties and is applied to food supplements and cosmetics, etc. And various studies have shown that carotenoids such as canthaxanthin are essential for poultry. For layers, high carotenoid intake improves egg yolk color, and dsm-firmenich provides the dsm-firmenich YolkFan™ which evaluates egg yolk color by the number 1 to 16 blades according to the shade of color for Carophyll product users. Carotenoids affect yolk color, but also contribute to fertility, hatchability, and chick quality in poultry breeders, making egg yolk not only a color but also a barometer of nutrients and hen health. So, for that reason, we can say a golden yolk is always coming from a healthy hen.

2.4 Minerals:

Eggs are also packed with essential minerals, including Selenium, Phosphorus, Iron and Magnesium. They are important for bone health, oxygen transport, immunity and different metabolic functions.

3. Positive Contribution to Human Health

3.1 Cardiovascular Health:

Contrary to past misconceptions, research now suggests that moderate egg consumption can have a neutral or even beneficial effect on cardiovascular health. The high-quality proteins and healthy fats in eggs help maintain healthy cholesterol levels and may reduce the risk of heart disease. Additionally, the presence of choline in eggs has been linked to a lower risk of heart disease.

3.2 Brain Health:

Eggs are an abundant source of choline and DHA (Docosahexaenoic acid), a nutrient that plays a crucial role in cognitive function and memory. These nutrients are especially important during pregnancy, as they contribute to the brain development of the fetus. Consuming eggs regularly can support brain health throughout all stages of life.

3.3 Eye Health:

Eggs are rich in antioxidants like lutein and zeaxanthin, which are essential for maintaining eye health. These compounds have been associated with a reduced risk of age-related macular degeneration and cataracts, two common eye conditions that can lead to vision impairment.

3.4 Weight Management:

Including eggs in a balanced diet may aid in weight management due to their high satiety value. Eating eggs can help control hunger, reduce overall calorie intake, and promote feelings of fullness, thus contributing to weight loss or weight maintenance goals.

3.5 Muscle Health:

The complete protein profile in eggs, along with essential amino acids, makes them an excellent food for muscle health. Whether consumed by athletes for muscle recovery or by older adults to prevent age-related muscle loss, eggs can play a vital role in supporting muscle strength and function.

3.6 Immune System Support:

The vitamins and minerals present in eggs, particularly vitamin A, vitamin D, and zinc, are essential for a robust immune system. Adequate consumption of eggs can help the body defend against infections and maintain overall immune function.

4. Optimal Consumption of Eggs

While eggs offer numerous health benefits, it is essential to consider the appropriate amount of egg consumption. The dietary guidelines vary depending on individual factors such as age, health status, and activity level. In general, most healthy individuals can safely consume up to 3-4 eggs per day as part of a balanced diet. However, those with specific health conditions or concerns about cholesterol levels should consult their healthcare professionals for personalized advice.

5. Importance of Eggs on Sustainability

Improving the nutritional value of eggs not only contributes to human well-being and a good lifestyle but also means that eggs can offer real potential to enhance maternal and child nutrition in developing countries, end hunger and achieve food security in a sustainable way. Studies promoting egg consumption for women and children as part of wider dietary improvements show that child growth indicators are significantly improved in the intervention group compared to controls. Also, since chickens can benefit from improved nutrition, it leads to improved egg qualities and contributes to Food loss & Waste reductions. Vitamin D is necessary for eggshell formation as well as bone development by assisting absorption of calcium. It leads to a reduction of Food (egg) loss & waste and by reducing egg breakage.

6. Conclusion

While potential malnutrition is increasing in many countries, it may be beneficial to place more significance on the egg, which has been found to be a rich source of many essential vitamins and nutrients. In light of this, dsm-firmenich is partnering with the International Egg Commission, an organization dedicated to the sharing of knowledge, expertise, and developments in egg nutrition globally. Improving nutrition is an important step in addressing micronutrient deficiencies and supporting optimal development and is a key factor in contributing to the UN's Sustainable Development Goals (SDGs). To increase the nutrient content of eggs, producers can take steps at the feeding stage to ensure that the end consumer is getting the most from their eggs and they are playing their part in ending hunger and improving global nutrition. Eggs are truly a nutritional powerhouse, providing an abundance of essential nutrients that contribute positively to human health. Their role in supporting cardiovascular health, brain function, eye health, weight management, muscle health, and immune support cannot be overstated. As we celebrate World Egg Day, let us recognize and appreciate the many benefits that eggs bring to our tables and, ultimately, to our well-being. Remember, incorporating eggs into a balanced diet can be an “egg-cellent” choice for a healthier and happier life.