World Health Organization (WHO) provides nutrition recommendations to strengthen resistance for adults during the increasing period of Covid-19 epidemic

In the context of the current increase in Covid-19 cases, nutrition supplementation to strengthen resistance is an important issue for people to protect their bodies against the disease. Below are the Nutrition Recommendations given by the World Health Organization (WHO) to help people have specific guidance in supplementing nutrients and strengthening the immune system.

The number of Covid-19 cases tends to increase – a sign of an outbreak again?

First appearing on December 31, 2019 in Wuhan city, Covid-19 (a respiratory disease caused by the SARS-CoV-2 virus) quickly spread and globally affected the lives of people. On March 11, 2020, the World Health Organization (WHO) officially declared Covid-19 a global pandemic.

In Vietnam, since the first case of Covid-19 in Ho Chi Minh City on January 23, 2020, the pandemic has spread throughout the country and brought extremely serious consequences to physical health, mental health of the people, as well as the speed of national economic development [5]. After days of anti-epidemic, on September 12, 2022, the Ministry of Health advised people to change epidemic prevention measures in accordance with the new situation, and at the same time loosened the rules of entry and exit, towards “normalization” of society.

However, at the beginning of April 2023, the recorded Covid-19 epidemic situation tended to increase. In particular, the recorded cases are increasing day by day and are mainly concentrated in the Northern region. According to the Hanoi Center for Disease Control (CDC), in just 1 week from April 7 to 14, the number of Covid-19 cases reached nearly 500 cases, 7 times higher than the previous week.

The Covid-19 pandemic is trending again in recent times (Photo: Freepik)

Although the situation of Covid-19 epidemic in our country is still at level 1 – everything is “green”, however, people still need to take absolute precautions, strictly follow all epidemic prevention principles and especially, strengthen nutrition supplements to help protect the resistance. A healthy body will be a solid “barrier” against bacteria and viruses that cause disease, and at the same time speed up recovery if you are unfortunate enough to get sick. Combined with full vaccination and compliance with epidemic prevention measures, the risk of Covid-19 infection will be minimized.

For the elderly, due to the decline in the function of organs in the body over time, this subject has to face many health problems. In particular, the immune-generating function is also reduced, so the resistance is weaker. Therefore, the elderly are susceptible to infections, infectious diseases, and especially the current Covid-19 epidemic. Moreover, the elderly often have chronic diseases such as: hypertension, diabetes, kidney disease, respiratory disease (bronchitis, asthma, chronic obstructive pulmonary disease…). Therefore, the resistance of the elderly is lower than that of other age groups.

When the immune system of the elderly is underactive, the ability to recognize and fight pathogens is also greatly reduced. Infectious pathogens such as bacteria, viruses, especially the new strain of virus SARS-COV-2 easily penetrate the upper respiratory tract (nose, throat), then penetrate the lower respiratory tract (bronchi, lungs) and disease there. Meanwhile, SARS-COV-2 is a respiratory disease virus, with strong toxicity, if the elderly are infected with SARS-COV-2, it will make the existing chronic diseases promote the transition to advanced stage. acute illness and chronic exacerbations, making COVID-19 very severe and potentially fatal.

Therefore, strengthening the resistance of the elderly is a must-do right in the context of this complicated situation of the Covid-19 epidemic. Adults can strengthen their resistance in many different ways, however, special attention should be paid to nutrition factors. Nutrition plays an important role in the prevention and treatment of coronavirus, and also a solution to improve the body’s immunity and resistance, to fight infection and to help treat disease more effectively.

Strengthening the body’s resistance is essential in the context of complicated epidemics (Photo: Freepik)

Supplement enough nutrients, strengthen resistance against the complicated developments of Covid-19 (1)

Familiar, readily available, natural nutrients with negligible side effects are recommended in the context of the risk of Covid-19 resurgence. According to the World Health Organization (WHO) nutrition guidelines for adults, a daily balanced diet with adequate vitamins, minerals, fiber, protein and antioxidants helps prevent disease prevention. In particular, macronutrients such as protein play an important role in the production of antibodies for the body. Nutrients such as omega-3 fatty acids, vitamin C, vitamin E, phytochemicals such as carotenoids and polyphenols also all exhibit anti-inflammatory and antioxidant properties when ingested.

1) Variety of nutrients

Protein

As per the recommended dietary allowance (RDA), on an average an individual needs 0.8g/kg body weight. An adequate amount of protein intake is essential for antibody and complement production in the body. The protein consumed in the diet is broken down into amino acids which are then reassembled into antibodies and complement proteins that are the major players of the immune system. Amino acids play a major role in regulating the activation of macrophages, natural killer cells, B and T lymphocytes. They are important for the production of cytokines and cytotoxic substances . Amino acids also regulate key metabolic pathways of the immune response against infectious pathogens. The normal sustainance of immunocompetence requires adequate dietary provision of all amino acids. A protein deficient diet leads to an impaired immunity which in turn is directly related to an increase in COVID-19 infection risk. Amino acids like arginine and glutamine are very important in stimulating the immune system. Proteins of high biological value which contain essential amino acids and from healthy dietary sources such as from eggs, poultry, meat and fish also constitute an essential component of an anti-inflammatory diet

Lipid

Fatty acids in the diet significantly influence the immune response. Omega-3 and omega-6 fatty acids are two essential fatty acids which need to be consumed in the diet as the human body cannot synthesize them. The omega-3 fatty acids largely comprise of α-linolenic acid (ALA) from plant sources and docosahexanoic acid (DHA) and eicosapentanoic acid (EPA) from fish and seafood sources. The dietary intake of these omega-3 fatty acids has been demonstrated to trigger anti-inflammatory reactions in the body. On the other hand, omega-6 fatty acids such as arachidonic acid is a precursor of pro-inflammatory eicosanoids like prostaglandins and leukotrienes. High levels of omega-6 fats are found in refined vegetable oils and also in nuts and seeds. A healthy ratio of omega-6/omega-3 fatty acids is between 1:1–4:1. Omega-6 fats provide energy to the body but people should ideally consume more omega-3 fats. Omega-3 fatty acids change the composition of the phospholipid bilayer of the host cell membrane, thereby preventing viral entry. DHA and EPA get incorporated in the plasma membrane and affect the clumping of toll-like receptors. This results in prevention of signals that activate NF-κB, production of fewer pro-inflammatory mediators and eventually reduction in complications of COVID-19 infection. DHA and EPA also serve as precursors of resolvins D and E which reduce the production of pro-inflammatory mediators eventually resulting in a decrease in lung inflammation.

Carbohydrates and dietary fiber

Carbohydrate consumption has been reported to increase serotonin production, which in turn has a positive impact on a person’s mood. Thus, carbohydrate-rich foods have an anti-stress, self-medicating effect. However, the amount of carbohydrates in the diet needs to be regulated as excess carbohydrates may lead to obesity, diabetes and heart diseases which may increase the complications due to COVID-19 infection.

Dietary fiber is the portion of plant-derived food or analogous carbohydrates that cannot be completely broken down by human digestive enzymes. The dietary fiber has been found to have a prebiotic effect such as fostering the growth of beneficial microbes like Bifidobacterium sp. and Lactobacillus sp. and inhibiting the pathogens like Clostridium sp. This is of considerable interest as recently COVID-19 has been associated with gastrointestinal disturbances in addition to respiratory symptoms.

2) The nutritional significance of micronutrients

Vitamin

Vitamin A plays a crucial role in maintaining the morphology of the epithelium as well as in formation of a healthy mucus layer of the respiratory and gastrointestinal tract. The two major forms of vitamin A in the diet include preformed vitamin A and provitamin A carotenoids. The active forms of vitamin A include retinal, retinol and retinoic acid. A low vitamin A status is correlated with a hampered function of macrophages, neutrophils, T-cells as well as B-cells. The immunomodulatory role of vitamin A may play a crucial role in the fight against COVID-19 infection.

Table 1: Nutritional significance of micronutrients.

B vitamins (B1, B2, B3, B5, B6, B7, B9, and B12) are water soluble vitamins which form an integral part of several coenzymes. They play a crucial role in cell metabolism and participate in energy production. Vitamin B plays a pivotal role in activation of both the innate and adaptive immune responses, down regulates the production of pro-inflammatory cytokines and inflammation and also improves respiratory function considerably. B vitamins also reduce gastrointestinal problems, prevent hypercoagulability and reduce the duration of hospital stay for COVID-19 patients.

Vitamin C is a classical antioxidant which has a significant impact on the immune system. It influences the activity of phagocytes and T-lymphocytes. Ascorbic acid in the diet has been reported to lower the concentration of C-reactive protein. Vitamin C has been postulated to exhibit antiviral activity by augmenting the production of interferon proteins. Given the antioxidant and antiviral effect of vitamin C and its favorable safety profile it may be an effective choice for the treatment of COVID-19.

Vitamin D can be synthesized by the body in the presence of sunlight. The active form of vitamin D is calcitriol (1,25 dihydroxyvitamin D). It not only plays a regulatory role in calcium homeostasis and thus maintains bone health but also regulates the immune system. It has been proposed that vitamin D reduces the risk of microbial infections in three ways. Firstly, it augments the natural protective barriers by helping in the preservation of the tight junctions between epithelial cells. The disruption of these junctions is a pathogenic mechanism of the upper respiratory tract viruses. Secondly, vitamin D enhances the innate immunity by promoting the release of defensins and cathelicidins which have been demonstrated to exhibit antiviral effects. Thirdly vitamin D boosts the adaptive immunity by reducing the production of pro-inflammatory cytokines by TH1 cells and increasing the production anti-inflammatory cytokines by TH2 cells. Low levels of vitamin D are reported in many adults at the end of the winter season due to a limited exposure to sunlight. There is an observed difference in mortality due to COVID-19 between Northern Hemisphere and Southern Hemisphere. This indicates a possible role of vitamin D in governing the pathogenesis of COVID-19.

Vitamin E is a fat-soluble vitamin which includes both tocopherols and tocotrienols. It is a potent antioxidant. Vitamin E has been demonstrated to regulate the immune response by modulating the TH1/TH2 balance and initiation of T-lymphocyte signals. Vitamin E not only acts through anti-oxidant pathways to increase the number of T cells but it also increases mitogenic lymphocyte responses, IL-2 cytokine secretion, activity of natural killer cells and eventually decreases the risk of COVID-19 infection.

Minerals

Zinc: Zinc is an essential micronutrient which is required as a co-factor for many enzymes involved in antioxidant reactions . The deficiency of zinc causes oxidative stress and also influences both the natural and acquired immunity. It has been reported that a low zinc status increases the risk of viral infections. Several studies have shown that zinc interferes with the viral replication cycle by inhibiting viral uncoating, interfering with viral transcription, protein translation and polyprotein processing. It has been proposed that Zn+2 inhibits the replication of SARS-CoV by blocking the RNA synthesis via inhibition of the RNA-dependent RNA polymerase.

Selenium: Several antioxidant enzymes such as glutathione peroxidase, selenoprotein P, and thioredoxin reductase require the trace element selenium for their synthesis. Thus, the primary role of selenium is its ability to act as an antioxidant and quench the reactive oxygen species (ROS). Dietary selenium deficiency has been associated with a high level of pathogenicity of several viruses. The cure rate for COVID-19 was found to be significantly higher in patients with a high selenium intake in the diet. Studies have proven that supra nutritional levels of selenium might suppress not only the life cycle of SARS-CoV-2 but also its mutation to a more virulent form. This is because of the fact that both selenoproteins as well as redox-active selenium species in the selenium metabolic pool attenuate viral-induced oxidative stress, cytokine storm and organ damage. Another study has proven that sodium selenite oxidizes the thiol groups in the protein disulfide isomerase of the coronavirus, thereby rendering it incapable of penetrating the host cell membrane.

Iron: Iron homeostasis is tightly regulated during bacterial and viral infections. When there is an inflammatory response, iron absorption is decreased so as to limit the pool of iron available to the multiplying bacteria and viruses. However, some studies have demonstrated that during a prolonged period of iron deficiency, antibody production is considerably reduced. Iron also plays an important role in T-cell proliferation and maturation as well as regulation of cytokine production. A study has implicated the role of hyperferritinemia and an increased inflammatory state in COVID-19 pathogenesis.

Nutrition plays an important role in strengthening the body’s immune system (Photo: Freepik)

Phytochemicals

Polyphenols: Polyphenols are phenolic compounds derived from plants which are enriched with antioxidant and anti-inflammatory properties. Dietary polyphenols are broadly classified into four groups which comprise of phenolic acids, lignans, stilbenes and flavonoids. Several polyphenols, for example the flavonoid quercetin exhibits antiviral properties. Quercetin has been reported to decrease viral infectivity and hampers intracellular viral replication. There is a plethora of evidence highlighting the prebiotic effects of polyphenols on the gut. This may help to amend the dysbiosis of the gut microbiota reported to be triggered by SARS-CoV-2 infection. Curcuminoids have been shown to reduce the C-reactive protein (CRP) concentrations. 

Curcumin is the bioactive compound present in turmeric which has a multi-mechanistic mode of action. It can inhibit viral entry into the cell, encapsulation of the virus and viral proteases. It modulates various signaling pathways. Curcumin may play a beneficial role in treating the COVID-19 infection as it is capable of modulating various targets which are responsible for the attachment and internalization of SARS-CoV-2 in many organs such as kidney, liver and the cardiovascular system. It may also suppress fibrosis-associated pathways and pulmonary edema which are triggered in COVID-19 infection.

Carotenoids are tetraterpenoids. They include orange, red and yellow organic pigments produced by plants, algae and bacteria. Some of the common carotenoids are α- and β-carotene, lutein, zeaxanthin and lycopene. Carotenoids are well known for their antioxidant properties and quenching of ROS. Thus, low levels of carotenoids are associated with oxidative stress. Antiviral roles of lutein, carotene and zeaxanthin have been reported. Some carotenoids serve as a precursor of vitamin A which is directly associated with immunomodulating functions. It has been reported that carotenoids alleviate the inflammatory responses that lead to lung damage during COVID-19 infection.

The nutritional significance of probiotics

Some patients with COVID-19 have been reported to show intestinal microbial dysbiosis which refers to an imbalance in the composition and function of the intestinal microorganisms. This highlights the involvement of the gut–lung axis in SARS-CoV-2 infection. Thus, for maintenance of health and prevention or treatment of the disease manipulation of the intestinal microbiota is often proposed as a potential approach]. This can be done by either stimulating the colonisation of the gastrointestinal tract by beneficial bacteria or by administration of probiotics. Probiotics are living microorganisms which confer health benefits to the host when administered in adequate amounts. They have been reported to boost the immune system. They also strengthen the integrity of the junction and maintain the morphology of the epithelium of the respiratory and gastrointestinal tract thereby reducing the risk of entry of SARS-CoV-2. Studies have reported a reduction in both upper and lower respiratory tract infections upon treatment with probiotics. Several probiotics such as lactic acid bacteria (LAB) have been shown to produce peptides which inhibit ACE2, the binding site of SARS-CoV-2. Thus, probiotics may serve as an adjunctive therapy in the alleviation of COVID-19.

In short, a high protein diet facilitates antibody production. A diet enriched in omega-3 fatty acids, vitamins and minerals is highly recommended during this pandemic situation . In the present-day scenario where many research groups are actively engaged in developing vaccines and novel therapeutics against COVID-19, a balanced nutrient status which reduces inflammation and oxidative stress may strengthen the immune system and thus may be the key to tackle the current situation. Several studies have shown that nutraceuticals have the ability to boost immunity and exhibit antiviral, antioxidant and anti-inflammatory effects. These comprise of vitamin C and D, zinc, selenium, curcumin, cinnamaldehyde, quercetin, lactoferrin, probiotics and several other natural compounds. Some of these phytonutrients may be grouped in correct combination to formulate a food supplement which in turn can not only boost immunity but also prevent viral spread. Thus, nutraceuticals provide both prophylactic as well as therapeutic support against COVID-19.

Table 2: Important dietary constituents which boost the immune system and their food sources

Some general notes on nutrition for adults during the Covid-19 outbreak (2)

In addition to the specific information and meaning of supplementing with essential nutrients, some tips and notes in formulating food in the context of the Covid-19 outbreak are also a solid foundation for improving the quality of the immune health of adults.

Nutrition notes recommended by the World Health Organization (WHO) to strengthen resistance during the Covid-19 outbreak:

Eat fresh and unprocessed foods everyday

Eat fruits, vegetables, legumes (e.g. lentils, beans), nuts and whole grains (e.g. unprocessed maize, millet, oats, wheat, brown rice or starchy tubers or roots such as potato, yam, taro or cassava), and foods from animal sources (e.g. meat, fish, eggs and milk).

Daily, eat: 2 cups of fruit (4 servings), 2.5 cups of vegetables (5 servings), 180 g of grains, and 160 g of meat and beans (red meat can be eaten 1−2 times per week, and poultry 2−3 times per week).

For snacks, choose raw vegetables and fresh fruit rather than foods that are high in sugar, fat or salt.

Do not overcook vegetables and fruit as this can lead to the loss of important vitamins.

When using canned or dried vegetables and fruit, choose varieties without added salt or sugar.

Drink enough water every day

Water is essential for life. It transports nutrients and compounds in blood, regulates your body temperature, gets rid of waste, and lubricates and cushions joints.

Drink 8–10 cups of water every day.

Water is the best choice, but you can also consume other drinks, fruits and vegetables that contain water, for example lemon juice (diluted in water and unsweetened), tea and coffee. But be careful not to consume too much caffeine, and avoid sweetened fruit juices, syrups, fruit juice concentrates, fizzy and still drinks as they all contain sugar.

Eat moderate amounts of fat and oil

Consume unsaturated fats (e.g. found in fish, avocado, nuts, olive oil, soy, canola, sunflower and corn oils) rather than saturated fats (e.g. found in fatty meat, butter, coconut oil, cream, cheese, ghee and lard).

Choose white meat (e.g. poultry) and fish, which are generally low in fat, rather than red meat.

Avoid processed meats because they are high in fat and salt.

Where possible, opt for low-fat or reduced-fat versions of milk and dairy products.

Avoid industrially produced trans fats. These are often found in processed food, fast food, snack food, fried food, frozen pizza, pies, cookies, margarines and spreads.

Eat less salt and sugar

When cooking and preparing food, limit the amount of salt and high-sodium condiments (e.g. soy sauce and fish sauce).

Limit your daily salt intake to less than 5 g (approximately 1 teaspoon), and use iodized salt.

Avoid foods (e.g. snacks) that are high in salt and sugar.

Limit your intake of soft drinks or sodas and other drinks that are high in sugar (e.g. fruit juices, fruit juice concentrates and syrups, flavoured milks and yogurt drinks).

Choose fresh fruits instead of sweet snacks such as cookies, cakes and chocolate.

Building a food recipe in the face of the Covid-19 outbreak is a solid foundation for optimizing immune health (Photo: Freepik)

Avoid eating out

Eat at home to reduce your rate of contact with other people and lower your chance of being exposed to COVID-19. We recommend maintaining a distance of at least 1 metre between yourself and anyone who is coughing or sneezing. That is not always possible in crowded social settings like restaurants and cafes. Droplets from infected people may land on surfaces and people’s hands (e.g. customers and staff), and with lots of people coming and going, you cannot tell if hands are being washed regularly enough, and surfaces are being cleaned and disinfected fast enough.

Counselling and psychosocial support

While proper nutrition and hydration improve health and immunity, they are not magic bullets. People living with chronic illnesses who have suspected or confirmed COVID-19 may need support with their mental health and diet to ensure they keep in good health. Seek counselling and psychosocial support from appropriately trained health care professionals and also community-based lay and peer counsellors.

Nutricare Gold – Comprehensive nutrition, quick recovery during the Covid-19 outbreak

During the outbreak of Covid-19 epidemic, strengthening resistance to prevent risks from the disease has become more urgent than ever. The selection of nutrition products that help strengthen immunity and restore health quickly plays an important role in protecting the body from harmful agents.

Nutricare Gold – comprehensive nutrition, quick recovery is a comprehensive nutrition solution to help strengthen resistance. The product is considered the “golden key” to fully meet the nutrition needs of the adults, especially during the return of the epidemic.

Nutricare Gold adds 38 essential nutrients (Zinc, Antioxidant (A, C, E & Selenium) and an easily absorbed protein system (Whey Protein, Casein Protein and Soy Protein) to help strengthen resistance and restore health. The product also contains HMB, rich in Calcium, and vitamin D3 to help strengthen bones and muscles. At the same time, the nutrient Lactium in this product has been clinically proven to help sleep well, reduce fatigue, and help elderly people have a good night’s sleep, avoid stress.

Besides, Nutricare also contains MUFA and PUFA duo to help reduce atherosclerosis, good for the heart. FOS soluble fiber supports digestive function, effectively preventing constipation.

With the support of Nutricare Gold, the adults can be assured of health problems during the return of the epidemic. Nutricare Gold is an effective nutrition solution that not only supports strengthening resistance, fast recovery of health for the adults, but also eliminates the worry of muscle and joint pain, fatigue due to insomnia.

Conclusion

Prevention is better than cure, even though fully vaccinated, everyone still needs to strictly follow the regulations on Covid-19 prevention and control, and actively protect themselves right from the daily diet to enhance their immune health, to support to improve resistance, to avoid disease affecting life, working and studying.