Omega-3 Enriched Eggs and Benefits for Human Health

Introduction

Nowadays, food is eaten to satisfy hunger, to provide the necessary nutrients to us humans and also to prevent nutrition-related illnesses in order to improve physical and mental well-being (SIRÓ et al., 2008). However, human nutrition has been characterized by excessive intake of sodium, cholesterol, omega-6 fatty acids and calories, and by low intake of omega-3 fatty acids, fibers, vitamins, antioxidants and trace minerals. These dietary and nutritional imbalances have increasingly contributed to the high incidence of obesity and noncommunicable diseases, resulting from cardiovascular diseases, which can lead to death (MOKDAD et al., 2003). According to the health surveillance research on risk and protective factors for chronic diseases carried out in 2018, in Brazil, more than half of the Brazilian population (55.7%) is overweight (MINISTÉRIO DA SAÚDE, 2019).

In view of this situation, consumers have sought to learn more about healthy eating. As demonstrated by the Ministry of Health (2019), regular consumption of fruits and vegetables increased by 15.5% between 2008 and 2018; the intake of soft drinks and sugary drinks decreased by 53.4% between 2007 to 2018 among adults in cities. Thus, there is a general movement towards a more balanced diet among consumers. The healthy food market in Brazil is expected to grow 4.0% annually until 2021, placing Brazil in the fifth position in the ranking of the most important countries for the healthy food sector (EUROMONITOR INTERNACIONAL, 2017). This situation suggests that there is great potential for foods consumed regularly, when these are converted into functional foods by changing their composition, as it includes certain nutrients beneficial to health.

One way to obtain functional foods is to change their compositions, in order to make it more suitable to meet nutritional recommendations, such as omega-3 enriched eggs. The increase in egg intake is perfectly suited in this condition. In 2020, egg consumption in Brazil reached a record, according to data published by the Brazilian Association of Animal Protein (ABPA, 2021) each Brazilian ate 251 eggs during the year. The reasons that explain high egg consumption are the recent studies that confirm the health benefits through egg consumption, for example, according to an article published on the website Avisite (2020), nowadays immunity has been widely discussed as a tool of resistance and support for the conditioning of the body in order to maintain health, stating that eggs are generally indicated to increase immunity. Besides, some studies have shown that high-density lipoprotein cholesterol (HDL-C) increases with the consumption of whole eggs during moderate caboydrate (CHO) restriction in overweight individuals, suggesting that eggs may even promote some heart-healthy effects (MUTUNGI et al., 2008). Consumption of omega-3 enriched eggs results in the modulation of some blood biochemical parameters, which are associated with reduced risk for cardiovascular mortality and diabetes (OHMAN et al. 2008).

Benefits of egg consumption for human health

Eggs are of particular interest when related to healthy and functional foods. Egg is considered moderate source of energy, approximately 150 kcal / 100 g of eggs, it is source of high quality protein and it has great culinary versatility and low economic cost. In addition, eggs can still play an important role, particularly in the diet of those risk groups for low nutrient intake, such as the elderly, pregnant women and children (NATOLI et al., 2007). And it must be considered that eggs can be consumed worldwide, without restrictions by religious groups (ABEYRATHNE et al., 2013).

Egg is the product of efficient biological transformation carried out by the laying hen (Gallus gallus). This bird transforms food resources of less biological value into a product of high nutritional quality for human consumption (BERTECHINI, 2005). Egg is an affordable food; it has high nutritional values and provides 18 vitamins, minerals, proteins and lipids. In addition, its composition can be affected by factors such as diet, lineage and environmental factors. The nutrients content of eggs is shown in table 1. Some nutrients, such as zinc, selenium, retinol and tocopherols present in eggs have antioxidant activity which protects humans against degenerative processes as cardiovascular diseases (NATOLI et al., 2007).

According to Bertechini (2005), the egg can be considered the greatest ally to rehabilitate human nutrition, in addition to other important nutritional contributions. There is scientific evidence that eggs contain active compounds that can play a role in therapy and in the prevention of chronic infectious diseases, once the egg has antimicrobial, immunomodulatory, antioxidant, anticancer, antihypertensive properties (ABEYRATHNE, et al., 2013). In addition, eggs are an important source of lecithin, in the form of phosphatidylcholine, an important structural and functional component of biological membranes. Lecithin and choline present in eggs have numerous functions, which include phospholipid synthesis, neurotransmission metabolism, in addition to being essential for brain development (JUNG et al., 2012).

As described, it is observed that egg is a nutritious food to be included in the diet of people of different age groups, and it can also play an important role in those diets with a risk of low nutrient intake. In addition to all the nutrients naturally present in the egg, it is possible to improve its composition by manipulating the laying hens diet and ensuring that this food provides significant amounts of health-promoting nutrients, such omega-3 polyunsaturated fatty acids.

Omega-3 Enriched Eggs and Benefits for Human Health - Image 1

Fatty acids

Fatty acids are carboxylic acids found by esterifying natural lipids (THAIN, 1985). According to the chemical structure, fatty acids are divided into monounsaturated, polyunsaturated and saturated. Monounsaturated fatty acids have only a double bond between the carbons in the chain, while polyunsaturated ones have two or more unsaturation and saturated fatty acids have only single bonds between the carbons in the chain (TIRAPEGUI, 2000).

Fatty acids can be represented by the number of carbons and degree of unsaturation, indicating the number of double bonds, for example, C18: 0 stearic acid, C18: 1 oleic acid. From the metabolic, physiological, biochemical viewpoint it is necessary to specify the position of the last double bond of unsaturated fatty acids. This information should be added to the numerical representation of an unsaturated fatty acid. Thus, in addition to the indicative numbers of carbons and double bonds, an indication of the position of the last double bond must also be presented, using the letter n followed by the number indicating the amount of carbons that are distant from the last double bond to the terminal methyl group. For example, linoleic acid (9, 12-C 18:2) is represented by 18:2 n-6, in which the latter double bond is from 6 carbons to methyl terminal, and linolenic acid (9,12,15C 18:3) is represented by 18:3 n-3 because the last double bond is from 3 carbons to the terminal methyl (TAHIN, 1985).

Mammals and birds synthesize almost all fatty acids except those called essentials. Linoleic acid (LA, n-6) and α-linolenic acid (ALA, n-3) are considered essential and therefore these fatty acids must be present in the diet (LEIFERT, 1999). After ingesting LA and ALA, a series of chemical reactions mediated by enzymes occur, producing long-chain polyunsaturated fatty acids (PUFAs) such as arachidonic acid (AA), eicosapentaenoic acid (EPA), docosaexaenoic acid (DHA) and docosapentaenoic acid (DPA) (Figure 1). In these reactions there is competition between enzymes; excess of n-6 PUFAs limits the formation of n-3 PUFAs (TIRAPEGUI, 2000). While the greater availability of n-3 PUFAs reduces the levels of arachidonic acid, due to the inhibition of catabolism and the formation of this acid from linoleic acid (LANDS et al., 1973).

According to Simopoulos (2000), many years ago, human beings ate a diet with an n-6: n-3 ratio close to 1, however, due to changes in eating habits, this ratio gradually increased, reaching values from 10: 1 to 25: 1, in western diets. In the last decades, it has been observed in several countries the fatty acid intake reaching n-6: n-3 ratios between 10: 1 to 20: 1; in some cases it is possible to find ratio up to 50: 1 (SIMOPOULOS, 2002). Ingestion of n-6 and n-3 PUFAs in adequate proportions is necessary to occur balance in the transformation of fatty acids in cells. The 4: 1 ratio between n-6 and n-3 fatty acids has been shown to be excellent for the transformation of α-linolenic acid into long-chain n-3 PUFAs, such as EPA and DHA. Ratios between n-6 and n-3 equal to 2: 1 to 3: 1 have been recommended in order to enable greater conversion of ALA into DHA (INNIS, 2006).

Omega-3 enriched eggs

According to Holland et al. (1997), the lipid fraction of the egg yolk is composed of 8.7 g of saturated fatty acids; 13.2 g of monounsaturated fatty acids; 3.4 g of PUFAs and 1.12 mg of cholesterol, per 100 g of fresh yolk. The yolk lipid profile can be modified by changing the kind or the amount of fatty acid in the laying hen's diet. From the possibility to improve egg lipid composition through incorporation of n-3 PUFAs in the laying hen diet in order to bring benefits to consumers, researches have been developed to identify n-3 sources and their inclusion level in the feed to produce omega-3 enriched eggs.

The addition of ingredients rich in n-3 PUFAs (ALA, EPA and DHA) in the feed increases their concentration in the egg yolk of laying hens (GALOBART et al., 2001; GROBAS et al., 2001; LOPES et al., 2013; NEIJAT et al., 2016; KHAN et al., 2017; FENG et al., 2020).

A recent study conducted by Oliveira et al. (2018) in Brazil showed that the inclusion of the Schizoquytrium microalgae flour, a DHA source, in the diet for laying hens improved the egg omega-3 content. This research was carried out to determine the level of the microalgae flour in the feed that would guarantee the production of omega-3 enriched eggs. In this study, the inclusion of 0.4% of the microalgae flour in the feed, corresponding to 0,112% DHA (1.12 mg/g feed), during seven days, increased the concentration of EPA plus DHA in the egg by more than 50%, reaching 142 mg of EPA + DHA per egg. Furthermore, by increasing the inclusion of microalgae flour (0.0; 0.4; 0.8; 1.2%) in the feed, EPA + DHA content exceeded 200 mg per egg.

Currently the poultry industry has promoted the enrichment of the eggs with n-3 PUFAs in order to attend consumers concerned about eating healthier foods. Besides to meeting the market demand for healthy foods, the marketing of omega-3 eggs increases producer’s income, since the increase in the essential nutrients content for health promotion, adds value to the egg, until then considered standard food. In Brazil, the producer usually obtains a margin twice as high from the sale of omega-3 enriched eggs in relation to that obtained from the sale of standard eggs. In Brazil, the market for omega-3 enriched eggs is still small, comprising about 0.5% of the total eggs produced, so there is a significant possibility of expansion, in order to meet a growing demand for healthy products by consumers.

In Brazil, the production of omega-3 enriched eggs currently follows National Health Surveillance (ANVISA) guidelines. According to the resolution “Resolução da Diretoria Colegiada - RDC” No. 54 (ANVISA, 2012) which provides the Technical Regulation of Complementary Nutritional Information. This resolution considerers omega-3 fatty acids enriched food a portion per 50 g or 50 ml in prepared dishes, containing at least 600 mg of ALA or at least 80 mg of EPA plus DHA.

Omega-3 fatty acids and human health benefits

In recent decades, it has been proven that adequate diets in concentration of n-3 PUFAs play an important role in the prevention and treatment of various diseases (TEITELBAUM & WALKER, 2001; LIMA et al., 2008). N-3 PUFAs have greatest ability to reduce the triacylglycerol and total serum cholesterol, increase the level of serum HDL and activate the lipid metabolism (SILVA et al., 2017; JULIBERT et al., 2019). Li et al. (2020) reviewed 89 papers relating the intake of EPA and DHA sources and the risk of mortality from some diseases and it was observed in 55 papers eating two to four servings of fish per week significantly reduces the risk of mortality from heart disease and cardiovascular, gastrointestinal cancer, metabolic syndromes, dementia and Alzheimer's disease. In this sense, the availability of omega-3 enriched eggs at a more affordable cost in relation to fish, favors a greater number of people to acquire some food rich in EPA and DHA.

In the immune system, n-3 PUFAs act on intercellular and intracellular mediators (POMPÉIA et al., 2000). EPA and DHA fatty acids are potent anti-inflammatory agents and both have been used successfully in the treatment of autoimmune inflammatory conditions, such as psoriasis and inflammatory arthritis, in addition, these fatty acids have an antithrombotic effect (HU et al., 1987; SHAPIRO et al., 1996; MILES et al., 2012). Various mechanisms of cellular anti-inflammatory action of EPA and DHA have been demonstrated in several studies, including their incorporation into cell membranes, resulting in the synthesis of anti-inflammatory eicosanoids (LORDAN et al., 2017; LORDAN et al., 2020).

In addition to the human health benefits already mentioned, EPA and DHA can still play a crucial role in the prevention and treatment for COVID-19 and other respiratory syndromes, especially those caused by Influenza sp. EPA and DHA might serve as a substrate for the synthesis of specialized lipid mediators such as maresins, resolvins and protectins, which in turn reduce the replication of the Influenza virus (Morita et al., 2013) and thus potentially affect manifestations of diseases viral (RUSSEL et al., 2013). It is suggested that EPA and DHA can inactivate enveloped viruses, such as SARS-CoV-2, which causes COVID-19 disease. Hilmarsson et al. (2006) propose that these n-3 PUFAs cause the rupture of viral envelopes through the destruction of membrane integrity, among other mechanisms. A proper diet, with balanced n-6: n-3 ratio (below 4:1) intake should be a way to control the pandemic of COVID-19 (SIMOPULOS, 2021).

Omega-3 enriched eggs and human health benefits

The daily recommendation for n-3 PUFAs follows some guidelines such as the Health and Welfare of Canada (1990) which recommends an intake of 5% of the total diet energy in the form of n-3 PUFAs; whereas in the United States, the Dietary References Intakes (Otten et al., 2006) recommends consumption of 267 mg of EPA + DHA per day for adult men. British Health Organizations suggest a daily intake of 0.5 to 1.0 g of EPA + DHA (KRIS-ETHERTON et al., 2000). Long-chain fatty acids specifically EPA and DHA, classified as n-3 PUFAs, are essential for human health. These fatty acids promote adequate neonatal formation, development of cognitive functions, effects on the immune system and cardiovascular health in adults and children. The modest consumption of one to two servings of fish per week providing 250 mg/day of EPA + DHA reduces the relative risk of cardiovascular disease (MOZAFFARIAN & RIMM, 2006). However, it is important to emphasize the omega-3 foods, such as fish are not commonly found on supermarket shelve, at an affordable cost. The egg, naturally present in the daily life of Brazilians, if enriched with n-3 PUFAs, it might contribute to greater availability of these nutrients in the diet of a greater number of people.

The amount of EPA + DHA in an enriched egg varies considerably from around 100 to 500 mg per egg. The most popular brand of omega-3 eggs claims just 100 to 125 mg of omega-3 per egg; thus, the intake of two omega-3 enriched eggs per day provides the same amount of DHA contained in two DHA capsules, which are 60% more expansive than two enriched eggs. Furthermore, the intake of two omega-3 enriched eggs per day corresponds the same amount of DHA contained in 450 g of salmon per day, which is 65% more expensive than two omega-3 eggs. Omega-3 enriched eggs might contribute to the dietary intake of these nutrients therefore; they might be an alternative source of these essential fatty acids, which are normally found in fish (KHAN et al., 2017). Direct consumption of EPA and DHA is the most effective means for increasing the content of health-giving n-3 PUFA in the lipids of the blood plasma and phospholipids of the cell membranes (JAČEK et al., 2020).

It is interesting to enrich animal products by supplementing n-3 PUFAs sources in animal feed, improving n-6: n-3 ratio in human diet, for example, through the intake of omega-3 enriched eggs. The need to reduce the n-6: n-3 ratio in current diets has been suggested due to a 70% reduction in the mortality rate in cardiovascular patients, when the ratio was 4: 1, as well as a reduction in inflammation resulting from rheumatoid arthritis, with a ratio of 3 to 4: 1, through the supplementation of EPA, DHA and ALA, all n-3 PUFAs (LOGERIL et al., 1994; JAMES & CLELAND, 1997; BROUGHTON et al., 1997). Direct ingestion of EPA and DHA is more efficient for absorption and use of n-3 PUFAs in the organism, since according to (Domenichiello et al., 2015) less than 1% of ALA is converted to DHA.

In an study to evaluate the effects of daily consumption of standard eggs and omega-3 enriched eggs, during one month by healthy individuals (men and women) over 45 years old without medication that could influence inflammatory parameters or blood lipids it was observed significant decreases in plasma glucose and in apoliprotein B1: apoliprotein A1 ratio through daily intake omega-3 enriched eggs (OHMAN et al., 2008). According to these researchers apoliproteins and apoliprotein B1: apoliprotein A1 ratio are considered to be superior as cardiovascular risk markers to the traditional blood lipid markers as total cholesterol, for example, then, they conclude addition of one egg regular per day to the normal diet had no negative impact on blood lipids, since total cholesterol and low density lipoprotein fraction (LDL) were not affected by daily consumption of omega-3 enriched eggs.

Conclusion

Commercial production of omega-3 enriched eggs is already a reality in Brazil, however, it is still little known and widespread in society. The addition of omega-3 sources at adequate levels in the laying hens feed allows producing omega-3 enriched eggs on a commercial scale. The availability of omega-3 enriched eggs contributes significantly to people's good body and mental health, besides to adding value to the egg, increasing income to the producer. Omega-3 enriched eggs create value for society as a whole.

Omega-3 enriched eggs may contribute to greater availability of these nutrients in the daily diet of a large part of the population, due to their versatility in preparation, in addition to the affordable cost. Adequate intake of n-3 fatty acids can prevent the occurrence of various diseases, especially those resulting from chronic inflammatory conditions.

And finally, there is the potential that omega-3 (AA, EPA and DHA) fatty acids may inactivate enveloped viruses (ZABETAKIS et al., 2020), which might reduce the infectious condition caused by SARs-CoV-2 virus. Omega-3 fatty acids might be a safe relatively inexpensive prophylactic and treatment approach for those who are at high risk and those who have the disease (HATHAWAY et al., 2020).