Know the eggs
Eggs offer a moderate calorie source (about 150 kcal/100 g), a protein of excellent quality, great culinary versatility and low economic cost.
Eggs can be a nutritious inclusion in the diet for people of all ages and at different stages of life. In particular, eggs may play a particularly useful role in the diets of those at risk of low-nutrient intakes such as the old, pregnant women and children.
Additionally, it must be mentioned that eggs can be consumed throughout the world, having no use restrictions on religious grounds.
Are the eggs dangerous for health?
Eggs are a controversial food for nutritional experts and health agencies, because of the saturated fat content (about 3 g/100 g) and cholesterol content (about 200–300 mg/100 g).
Owing to these two characteristics, during the past 40 years, the public had been warned against frequent egg consumption due to the high cholesterol content in eggs and the potential association with CVD (cardiovascular diseases). This was based on the assumption that high dietary cholesterol consumption is associated with high blood cholesterol levels and CVD. Afterwards, subsequent research suggests that dietary cholesterol in general and cholesterol in eggs in particular have limited effects on the blood cholesterol level and on CVD .
Unfortunately, eggs and egg-derived foods are responsible for a large number of food-borne illnesses each year, mainly caused by Salmonella.
For this reason, as well as for their lower price and ease of handling and storing compared to shelled eggs, the food service industry and commercial food manufacturers have shown an increasing interest in the use of liquid pasteurized egg products instead of fresh whole eggs.
Eggs are an inexpensive and highly nutritious food, providing 18 vitamins and minerals.
The macronutrient content of eggs include:
- low carbohydrates
- about 12 g per 100 g of protein and lipids(most of which are monounsaturated)
Some of these nutrients, such as zinc, selenium, retinol and tocopherols, are deficient in people consuming a western diet, and given its antioxidant activity, can protect humans from many degenerative processes, including CVD.
The presence of compounds with antimicrobial, immunomodulator, antioxidant, anti-cancer or anti-hypertensive properties have been reported in eggs.
Lysozime, ovomucoid, ovoinhibitor and cystatin are biologically active proteins in egg albumen, and their activity prolongs the shelf life of table eggs.
Some of these protective substances are isolated and produced on an industrial scale as lysozymes and avidin. Additionally, eggs are an important source of lecithin and are one of the few food sources that contain high concentrations of choline.
Lecithin, as a polyunsaturated phosphatidylcholine, is a functional and structural component of all biological membranes, which acts in the rate-limiting step of the activation of membrane enzymes such as superoxide dismutase. It has been suggested that ineffective activation of these antioxidant enzymes would lead to increased damage of membranes by reactive oxygen species. In addition, lecithin increases the secretion of bile, preventing stagnation in the bladder and, consequently, decreases the lithogenicity.
However, as a component of egg lecithin, choline has numerous important physiologic functions, which include the synthesis of phospholipids, the metabolism of methyl and cholinergic neurotransmission, and it is a required nutrient that is essential for the normal development of the brain.
It was suggested that egg-yolk phosvitin (important nutritional component) has the potential to be used as a natural bioactive compound as a hyper-pigmentation inhibitor for human skin.
Good for eyes
The eggs contain too carotenoids that are best known for their function in the neural retina, where they are found in high concentration and, along with their isomer mesozaexanthin, are termed macular pigment.
Lutein and zeaxanthin are known to serve light-absorbing and blue-filtering optical functions, as well as antioxidant and anti-inflammatory functions, and thereby, is considered to play a role reducing immune-mediated macular degeneration and age-related cataract formation. They are in eggs less than vegetables, but with an important difference: lutein and zeaxanthin from eggs are much more bioavailable. They are lipophilic compounds. So, they need ingestion of fat (ie salad with a full fat dressing). Vegetables contains fiber, that interfere with absorption of fat and other lipophilic compounds. Intake of 2-3 eggs/day supported greater improvements in HDL function and increases plasma antioxidants.
Good for Gout
Owing to their high nutritional value, eggs are also an important food that should be included in the planning of diets for patients, and are especially valuable in feeding people with gout, because it is a source of protein that does not add purines.
Good for Sports
For people in sports training, egg proteins may have a profound effect on the training results, because, by its inclusion in the diet, it could be possible to enhance skeletal muscles synthesis
It is well established that essential amino acids stimulate skeletal muscle protein synthesis in animal and human models, and the protein in egg has the highest biological value.
Fifteen grams of egg white protein contain about 1300 mg of leucine (the third most common amino acid in egg, after glutamic and aspartic acids), and is also an abundant source of branched amino acids and aromatic amino acids. Recent data showed that leucine induces a maximal skeletal muscle protein anabolic response in young people, which suggests that egg white protein intake might have an important effect on body mass accretion.
Specifically, leucine stimulates skeletal muscle synthesis independently of all other amino acids in animal models and is a potent stimulator of the cell hypertrophy mammalian target of rapamycin complex pathway. Additionally, leucine decreases muscle protein breakdown and breakdown-associated cellular signaling and mRNA expression.
Benefit for general health
Eggs are rich in glycine betaine, mercaptan, sialic acid, vitamins, and minerals; they might directly affect human body blood vessel functions or cholesterol metabolism by regulating activities of related enzymes or indirectly affect blood lipid level by regulating protein, fat, and carbohydrate metabolism. For example, Cys and glutathione may help to remove free radicals. Egg contains vitamins A, E, B2, and B6 and vitamin B12, which are able to resist LDL oxidation, lower homocysteine accumulation, dilate blood vessels, and prevent the happening of the angina pectoris, atherosclerosis, and myocardial infarction.
The ratio of LDL and HDL in egg is the same as that in human blood and LDL maintains pattern conversion. Despite the existence of cholesterol in the egg yolk, its impact on CVD may be different from the cholesterol in other food sources such as meat. In addition, when cholesterol is increased from food, the body makes less in healthy individuals. When the body’s daily intake of cholesterol reaches more than 2 g, the absorption rate will gradually decrease, the synthesis of cholesterol in the body is reduced, and the neutral cholesterol content in the stool increases. If the cholesterol intake is low, cholesterol synthesis will increase to maintain a constant value
Adverse effects: wrong assumption for years
- In 1968, the American Heart Association (AHA) recommended that the dietary cholesterol consumption should be no more than 300 mg/day and emphasized no more than 3 egg yolks should be consumed per week.
- Later epidemiological studies and systematic reviews reported a marginal correlation between dietary cholesterol and/or egg intake and CVD incidence in the general population.
- Clinical studies have clearly shown that plasma compartment changes, resulting from dietary cholesterol consumption, are influenced by several factors such as genes, hormones, other dietary components, lifestyle, and the nutritional status of the subjects.
- All of these characteristics determine who would hyper-respond to dietary cholesterol and those who are hypo-responsive to intake. In addition, those individuals who hyper-respond to dietary cholesterol intake generally show increased LDL and high-density lipoprotein cholesterol (HDL).
- In a Chinese study, compared with non-consumers, daily egg consumption was associated with lower risk of CVD.Daily consumers also had an 18% lower risk of CVD death and a 28% lower risk of haemorrhagic stroke death compared to non-consumers.
Studies also found that eating large amount of eggs (10 eggs/day) does not significantly influence the serum cholesterol level comparing to the low intake (1 egg/day), and some even found there is a negative correlation.
What kind of problem then
Egg allergies represent one of the most common IgE-mediated food allergies in infants and young children.
Among infants and young children, egg allergy is the second most common food allergy after cow’s milk allergy.
Thus, a recent study found that factors as female gender, preterm delivery, having older siblings, maternal smoking during pregnancy or exposure in the first year to pets inversely associated with egg allergy. Child with a family history of allergy and those parents born in East Asia are at increased risk of egg allergy
Good for weight loss
After being debated for half a century, dietary cholesterol and egg intake finally got rid of the nature of “evil.” Moreover, recent studies reported that multiple bioactive components in eggs have potential benefits to overall health through the lifespan, such as supplying micronutrients, antioxidants, antimicrobials, and reducing risk of cancer and hypertension.
Some research results have shown that there was reduced energy intake after the breakfast with an egg and a bagel ,
larger weight loss after 8 weeks with the breakfast containing an egg and a bagel as part of a hypocaloric diet and significant change in satiety hormones after an egg in the breakfast.
The consumption of two eggs per day as compared to an oatmeal breakfast did not increase the LDL-C/HDL-C ratio, while increasing satiety as measured by fasting plasma ghrelin and VAS.
Bibliography
- Miranda JM, Anton X, Redondo-Valbuena C, et al. Egg and egg-derived foods: effects on human health and use as functional foods. Nutrients. 2015;7(1):706-29. Published 2015 Jan 20. doi:10.3390/nu7010706
- Kuang H, Yang F, Zhang Y, Wang T, Chen G. The Impact of Egg Nutrient Composition and Its Consumption on Cholesterol Homeostasis. Cholesterol. 2018;2018:6303810. Published 2018 Aug 23. doi:10.1155/2018/6303810
- Qin C, Lv J, Guo Y, et al. Associations of egg consumption with cardiovascular disease in a cohort study of 0.5 million Chinese adults. Heart. 2018;104(21):1756-1763.
- Diana M DiMarco, Gregory H Norris, Courtney L Millar, Christopher N Blesso, Maria Luz Fernandez; Intake of up to 3 Eggs per Day Is Associated with Changes in HDL Function and Increased Plasma Antioxidants in Healthy, Young Adults, The Journal of Nutrition, Volume 147, Issue 3, 1 March 2017, Pages 323–329, https://doi.org/10.3945/jn.116.241877
- https://academic.oup.com/jn/article/147/3/323/4669740
- Missimer A, DiMarco DM, Andersen CJ, Murillo AG, Vergara-Jimenez M, Fernandez ML. Consuming Two Eggs per Day, as Compared to an Oatmeal Breakfast, Decreases Plasma Ghrelin while Maintaining the LDL/HDL Ratio. Nutrients. 2017;9(2):89. Published 2017 Jan 27. doi:10.3390/nu9020089
