Discover the benefits that this superfood can bring you
| The image of eggs is probably the one that has undergone the greatest transformation over the years. Initially it was considered a staple food due to its high nutritional value (1950s) and later in the 1970s and 1980s it was considered that its consumption should be reduced due to a possible harmful effect on health. Nowadays, since the year 2000, eggs have been considered a fundamental foodstuff, with beneficial effects on health. |
1. COMPOSITION AND NUTRITIONAL VALUE OF EGGS
Eggs are a very heterogeneous food and can be divided into three phases: shell, yolk and white. In the table
-1 appears the nutritional value of the egg.
Egg yolk: 47% water, 16% protein, 34& fat, 0.6% carbohydrates
Egg white: 88% water, 10% protein, 0.03% fat, 0.8% carbohydrate.
a. Proteins
The percentage protein content of eggs (12%) is slightly lower than that of other protein foods such as meat (20%) and fish (18%). This protein is distributed heterogeneously between egg white and yolk, with the white being mainly protein, while the yolk contains, in addition to protein, the entire lipid fraction of the egg. Table 2 describes the amino acid content of eggs (mg/egg). The contribution of methionine+cysteine, lysine and phenylalanine+tyrosine is particularly noteworthy.
b. Lípidos
The fatty acid composition is favourable as there is a perfect balance between saturated and unsaturated fats with an IFA/SFA ratio of 1,77. This ratio is more favourable than the vast majority of meats (0.88 for lamb, 1.12 for beef, 1.36 for pork).
On the other hand, eggs have a high cholesterol content (400mg/100g).
Finally, it is particularly noteworthy that the fatty acid fraction is modifiable through diet. In recent years, eggs enriched in long-chain n-3 PUFA (omega-3), such as EPA and DHA, have become available. This has been achieved with feed enriched in these same fatty acids.
c. Minerales
To consider the nutritional value of eggs with regard to minerals, we will use the coverage of the recommended daily intake (RDA). This coverage in relation to the intake of 2 large eggs (120g) is 8% for iron and zinc, 16% for phosphorus, 11% for calcium, 4% for magnesium and 34% for selenium.
d. Vitaminas
El huevo es uno de los alimentos que reúne concentraciones más notables, tanto de vitaminas hidrosolubles como liposolubles. Todas las vitaminas liposolubles presentan valores altos, especialmente la K (62% de la CDR) y además tienen una alta capacidad de acumulación, según los piensos. En menor proporción presenta la vitamina B2 (30%) and Vitamins A, D, B12 and folic acid ranging from 12 to 16%.
e. Variabilidad de la composición del huevo
Various factors can induce changes in egg quality, affecting also the chemical composition and nutritional value. The elements that can be modified by feeding the hens include some minerals (iodine, fluorine, manganese), some vitamins (A, E, K, B1, B2, B12, biotin, pantothenate, folate) and some fatty acids, especially unsaturated (oleic, linoleic and linolenic,...).
On the other hand, table 3 shows the differences between the different types of eggs and the most frequent ways of preparing eggs.
2. EGG CONSUMPTION AND BLOOD CHOLESTEROL
Given the recommendations to restrict egg intake in the 1970s and 1980s, many studies were devoted to establishing the specific relationship between changes in egg intake and their impact on plasma cholesterol levels.
The conclusions on the effects of egg consumption indicate that, despite the high cholesterol content, it does not cause a substantial increase in plasma cholesterol and has a negligible influence on the ratio of LDL-cholesterol (bad)/HDL-cholesterol (good).
3. HEALTH AND HYGIENE CONSIDERATIONS
Eggs, due to their structure, are one of the safest foods. From the outside to the inside there are a number of barriers that protect it from external contamination. Therefore, it is difficult for the egg to become contaminated during the production stage on the farm. The risk factors are those that alter the structure of the shell and the outer cuticle. For this reason, washing to remove dirt is not authorised, as it would remove the layer that covers the pores of the shell from the entry of micro-organisms.
It is known that food poisoning, whether by salmonella or other micro-organisms, is caused by incorrect handling of fresh eggs and eggs that have not undergone thermal modification. The germs are never found inside the egg.
Basic recommendations on the handling and preservation of eggs:
a. Comprar huevos con la cáscara íntegra y sin suciedad aparente.
b. Respetar fechas de consumo y conservar siempre en el refrigerador.
c. Consumir siempre tras su preparación o cocción o guárdalos en el refrigerador durante poco tiempo.
d. Las mayonesas y otras salsas similares deben prepararse con una higiene extrema y siempre añadiendo limón o vinagre.
e. Manipular los huevos fuera de los recipientes, sartenes… que se vayan a batir, cocinar o servir, para evitar el contacto con la cáscara.
EGGS AS A FUNCTIONAL FOOD
Some egg components could be highlighted as having positive health properties. This fact could give the egg the possibility of being a functional egg (Hasler-2000).
a. Carotenos: neutralización de radicales libres, por lo que previenen el daño celular. Su contenido y propiedades varía dependiendo del caroteno.
b. Luteína y Zeaxantina: favorecen el mantenimiento de las funciones visuales.
c. Vitamina-E: neutraliza los radicales libres. Su contenido en el huevo puede aumentarse añadiendo un suplemento a los piensos.
d. Ácidos grasos ω-3 (DHA/EPA): reduce el riesgo de presentar enfermedad cardiovascular. Mejora las funciones visuales y mentales. Se puede añadir su concentración modificando el pienso.
e. Colina: favorece el mantenimiento y mejora las funciones cognitivas, especialmente la memoria.
Nutritional Tables
Table 2. Amino acid content of eggs, expressed as mg/egg 50g egg
| Amino acid | Whole egg | Clara | Yolk |
| Glutamic acid | 850 | 520 | 330 |
| Cysteine | 150 | 100 | 50 |
| Phenylalanine | 350 | 230 | 120 |
| Glycine | 220 | 140 | 80 |
| Histidine | 160 | 90 | 70 |
| Isoleucine | 360 | 210 | 150 |
| Leucine | 570 | 330 | 240 |
| Lysine | 450 | 250 | 200 |
| Methionine | 210 | 150 | 60 |
| Proline | 260 | 150 | 110 |
| Serina | 500 | 270 | 230 |
| Tyrosine | 280 | 160 | 120 |
| Threonine | 320 | 180 | 140 |
| Tryptophan | 110 | 70 | 40 |
| Valina | 430 | 270 | 160 |
Table-3 Egg composition and cooking methods.
Fresh egg | Boiled egg | Egg fried in oil | Tortilla | |
| Water | 75,8 | 75,7 | 70,3 | 71,7 |
| Energy (Kcal) | 145 | 145 | 184 | 171 |
| Protein | 12,5 | 12,5 | 13,4 | 14,6 |
| Grease | 10,5 | 10,5 | 14,5 | 12,5 |
| ACS | 3,1 | 3,1 | 4,3 | 3,7 |
| AGMI | 4,2 | 4,2 | 5,8 | 5 |
| AGPI | 1,3 | 1,3 | 2 | 1,5 |
| Cholesterol | 380 | 380 | 400 | 350 |
| Retinol | 200 | 200 | 220 | 225 |
| Vit E (eq) | 1,2 | 1,2 | 1,2 | 1 |
| Vit-B1 | 0,08 | 0,08 | 0,07 | 0,06 |
| Vit-B2 | 0,46 | 0,35 | 0,41 | 0,35 |
| Vit-B6 | 0,12 | 0,12 | 0,14 | 0,1 |
| Vit-B12 | 1,6 | 1,2 | 1,2 | 1,3 |
| Folate | 60 | 60 | 42 | 30 |
