Are “free-range eggs” and “selenium-enriched eggs” really more nutritious than ordinary eggs? The truth is…

Everyone knows that eggs are rich in nutritional value. Now you can see all kinds of eggs in the supermarket. In terms of breeding methods, there are free-range eggs, firewood eggs, antibiotic-free eggs, and organic eggs; in terms of function, there are Omega-3 eggs, selenium-rich eggs, and astaxanthin eggs; in terms of appearance, there are first-born eggs, double-yolk eggs, gray-shell eggs, pink-shell eggs, brown-shell/yellow-shell eggs, colorful eggs, and so on.

What are the differences between these eggs? Are expensive eggs really more nutritious than cheap ones? Are they more worth buying? Let's talk about it in detail today.

Too long to read

Let me give you the answer first: most “concept eggs” are marketing products and there is not much difference in nutrition.

1. Free range eggs, firewood eggs, and free range eggs: all are eggs laid by “free range” chickens, and there is no nutritional difference between them;

2. Antibiotic-free eggs: "Antibiotic-free" generally means no antibiotic residues. This is the minimum standard for selling eggs, but it does not mean that no antibiotics are used at all;

3. Organic eggs: higher grade than antibiotic-free eggs, they are eggs laid by chickens that have never used antibiotics. However, in the domestic breeding environment, it is difficult to use antibiotics throughout the entire process, so there is no need to pursue it;

4. Omega-3 eggs: The premium is almost entirely due to R&D costs. If you want to supplement Omega-3 polyunsaturated fatty acids, it is better to eat more fish;

5. Selenium-enriched eggs: Before eating, make sure you are really selenium deficient. Excessive intake of selenium can cause acute or chronic poisoning.

6. Astaxanthin eggs: It is not as cost-effective as eating algae or shrimp containing astaxanthin directly;

7. Newly laid eggs, double yolk eggs, and colored shell eggs: Their nutritional value is no higher than that of ordinary eggs, so there is no need to buy them specifically to eat.

Free range eggs, firewood eggs, free range eggs

What's the difference?

Free range chicken, firewood chicken and free range chicken correspond to free range chicken respectively. Many people cannot tell the difference between them because there is no difference at all . They are all free range chickens with the same scientific name Gallus domestiaus. In fact, "free range chicken", "firewood chicken" and "free range chicken" are all folk names.

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There are two levels of free-range chickens. Free-range chickens raised on a small scale by farmers can be considered free-range; the breeding model in Europe and the United States that uses a large flat floor with a roof and limited outdoor space is also considered free-range.

The counterpart of "free-range chickens" is "cage-raising". Most of China's large-scale egg-laying chicken farms are "cage-raising" because cage-raising takes up little space, is easy to manage, and has high egg collection efficiency.

However, in terms of nutritional content, studies have shown that free-range eggs have a higher fat content, but there is no significant difference in cholesterol and vitamin levels . Compared with hens kept away from the sun, the vitamin D in the eggs of hens exposed to the sun has increased by 4 times.

Antibiotic-free and organic eggs

Is it necessary to buy it?

"Antibiotic-free" and "organic" are another set of concepts alongside "free-range" and "cage-raised", and are used to indicate the biosafety standards of the breeding system.

1

Antibiotic-free eggs

Some commercial eggs in China today are advertised as "antibiotic-free", but in fact they only "meet the sales standards" . The standard for regular commercial eggs to be listed is that they have no antibiotic residues. Here, "no antibiotic residues" means that the instruments cannot detect them, not that antibiotics have not been used. In other words, any egg you can buy on the shelves of regular supermarkets, in theory, cannot be detected by instruments to show antibiotic residues, which is the minimum standard . Therefore, the so-called "antibiotic-free" is likely to be "pseudo-antibiotic-free".

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2

Organic eggs

"Organic eggs" are a higher level of eggs than "antibiotic-free eggs" and are also the highest standard of eggs . Organic eggs require that laying hens use antibiotic-free feed and no antimicrobial drugs are used during the livestock and poultry production cycle. That is, once laying hens start laying eggs, antibiotics are no longer needed (but they can be used before laying eggs). "Organic eggs" are organically raised, that is, laying hens grow under natural conditions throughout the process. Some regions even require grass-feeding without artificial feed . In addition, no antibiotics are used , and no feed or water containing antibiotics is used. Even antibiotic residues cannot be detected in the soil.

Additionally, studies have shown that pasture-fed hens can produce eggs that are rich in omega-3 polyunsaturated fatty acids without the adverse effects of oxidation.

From the perspective of breeding costs, organic breeding requires more time and money than ordinary free-range and large-scale cage breeding, so it is not surprising that the price is high. However, in the domestic breeding environment, it is actually difficult to avoid the use of antibiotics throughout the entire process, so there is no need to force the pursuit of organic.

Omega-3 eggs, selenium-enriched eggs, astaxanthin eggs

Is it necessary to buy it?

In principle, the diet of laying hens could also affect the nutritional quality of their eggs. For example, eggs rich in omega-3 fatty acids could be produced by feeding hens a diet containing polyunsaturated fats such as fish oil, chia seeds or flax seeds.

1

Omega-3 Eggs

my country has issued the standard "NY/T 4069-2021 Omega-3 Polyunsaturated Fatty Acid Fortified Eggs" for this type of eggs. In short, the Omega-3 content of Omega-3 eggs is higher than that of ordinary eggs.

It should be noted that from a production perspective, adding polyunsaturated fat ingredients does not significantly increase costs, and the price premium of Omega-3 eggs may be caused by increased research and development costs . Therefore, how much price consumers can accept to cover the extra Omega-3 nutrition is a matter of opinion.

Personally, I think that if an Omega-3 fortified egg costs more than 5 yuan, it is unnecessary. In daily diet, deep-sea fish, tofu (soybeans), and melon seeds can also supplement Omega-3 to varying degrees.

Fish can also supplement Omega-3 polyunsaturated fatty acids, which is more cost-effective than Omega-3 eggs.

2

Selenium-enriched eggs

Adding selenium to laying hen feed can theoretically produce eggs with a higher selenium content.

As a consumer, it is also worth considering whether to choose selenium-enriched eggs. Insufficient selenium intake may lead to Keshan disease, Kaschin-Beck disease, liver disease and malignant tumors, as well as decreased immunity. However, when excessive doses of inorganic selenium (≥20 mg/kg) are taken at one time or when inorganic selenium levels of 5-20 mg/kg are taken for a long time, it will cause acute or chronic poisoning symptoms, such as hair loss, nail loss, focal congestion, swelling, ulcers, dulled perception, numbness of the limbs, and paralysis of the whole body.

Therefore, before eating selenium-rich eggs, you should make sure whether you have symptoms of selenium deficiency and do not blindly consume large amounts of selenium-rich eggs .

3

Astaxanthin Egg

When laying hens eat feed rich in astaxanthin, astaxanthin can also accumulate in their eggs.

The main purpose of adding astaxanthin to laying hen feed is to increase the stability of egg yolks, not to allow people to eat more astaxanthin. Therefore, if you want to supplement astaxanthin, it is faster and more economical to eat some algae (seaweed, nori, laver) and shrimp rich in astaxanthin instead of spending more money to buy astaxanthin eggs. If your daily diet already includes shrimp and algae, there is no need to buy astaxanthin eggs.

Instead of spending money on anthocyanin eggs, it is better to buy more shrimps.

First-laid eggs, double-yolk eggs, colorful eggs

Is it necessary to buy it?

Most of the changes in the appearance of eggs that are visible to the naked eye do not involve any high-end technology. For example, first-born eggs and double-yolk eggs are when the laying hens have just started laying eggs. Their egg-laying performance is unstable, and they either lay small eggs or double-yolk eggs. Their nutritional value is no different from that of ordinary eggs .

Gray-shelled eggs, pink-shelled eggs, and brown-shelled/yellow-shelled eggs are caused by different egg-laying chicken breeds. The colorful eggs are probably laid by different egg-laying chicken breeds put together. It is not that one type of chicken can lay eggs of different colors. Among these eggs with different appearances, in my opinion, only double-yolk eggs are worth a relatively higher price, because the time of laying double-yolk eggs only accounts for a small part of the production cycle of egg-laying chickens. Scarcity makes things more valuable.

Therefore , compared with ordinary eggs, the nutritional value of newborn eggs and colorful eggs has not increased. There is no need to spend more money on them for daily consumption . However, it is understandable to buy them as gifts just to make them look good.

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How to choose and eat eggs?

Now that we know about the various types of eggs on the market, how should we choose eggs and how should we eat eggs?

1. If you have high dietary requirements, instead of spending time choosing eggs with prefixes, it is better to buy eggs with coded traceability produced by big brands in regular supermarkets. The supervision of the production process of such eggs will be stricter, and the freshness and hygiene level of the eggs will be more guaranteed.

2. If you don’t pursue coding traceability, you should at least pay attention to the production date and storage conditions . In theory, eggs in supermarkets can be stored at room temperature because of their fast circulation speed. It is recommended to store them in the refrigerator after buying them home.

3. In terms of consumption, cooked eggs are easier to digest than raw eggs and have a lower risk of salmonellosis. Studies have shown that the true ileal digestibility of cooked egg protein and raw egg protein is 90.9%±0.8% and 51.3%±9.8%, respectively.

4. If you are not pursuing the taste of raw eggs, it is recommended to heat them before eating.

Finally, I hope that after reading this article, everyone can eat delicious and nutritious eggs.

References

[1] Anderson, KE (14 June 2011). "Comparison of fatty acid, cholesterol, and vitamin A and E composition in eggs from hens housed in conventional cage and range production facilities". Poultry Science. 90 (7): 1600–1608. doi:10.3382/ps.2010-01289. PMID 21673178

[2] Kühn, Julia; Schutkowski, Alexandra; Kluge, Holger; Hirche, Frank; Stangl, Gabriele I. (1 April 2014). "Free-range farming: A natural alternative to produce vitamin D-enriched eggs". Nutrition. 30 (4): 481–484. doi:10.1016/j.nut.2013.10.002. ISSN 0899-9007. PMID 24607306

[3] Lopez-Bote, CJ; Sanz Arias, R; Rey, AI; Castaño, A; Isabel, B; Thos, J (May 1998). "Effect of free-range feeding on n−3 fatty acid and α-tocopherol content and oxidative stability of eggs". Animal Feed Science and Technology. 72 (1–2): 33–40. doi:10.1016/S0377-8401(97)00180-6

[4] Coorey R, Novinda A, Williams H, Jayasena V (2015). "Omega-3 fatty acid profile of eggs from laying hens fed diets supplemented with chia, fish oil, and flaxseed". J Food Sci. 80 (1): S180–7. doi:10.1111/1750-3841.12735. PMID 25557903

[5] Dieudonne, Dansou & Wang, Hao & Nugroho, Ramdhan & He, Weizhao & Zhao, Qingyu & Zhang, Junmin. (2021). Assessment of Response to Moderate and High Dose Supplementation of Astaxanthin in Laying Hens. Animals. 11. 1138. 10.3390/ani11041138.

[6] Evenepoel, P; Geypens B; Luypaerts A; et al. (October 1998). "Digestibility of cooked and raw egg protein in humans as assessed by stable isotope techniques". The Journal of Nutrition. 128 (10): 1716–1722. doi:10.1093/jn/128.10.1716. PMID 9772141.

Planning and production

Author: SamKakeru, practicing veterinarian

Review | Ruan Guangfeng, Deputy Director of Kexin Food and Health Information Exchange Center

Planning丨Cui Yinghao

Editor: Yang Yaping