Young children are very susceptible to minor illnesses and often relapse, especially during the changing seasons, when the weather changes erratically due to the weak immune system, causing many parents to worry. How to strengthen children’s resistance scientifically and effectively? This article gives you detailed answers, with in-depth knowledge about how the immune system works, the importance of nutrition, especially golden nutrients such as vitamins, minerals, and probiotics to strengthen children’s resistance.

1. Immune system: “Shield” protecting children from viruses

Immune system – a shield that protects children against all pathogens

The immune system plays a role in protecting the body from the invasion of pathogens such as viruses, bacteria, fungi, and parasites…¹ Clear understanding of the immune system’s working mechanism allows parents to take more effective care of their children.

The immune system is a complex network of cells, tissues, and organs that work together to fight off disease-causing invaders. It’s like a mighty army, always ready to protect your child’s body from bacteria, viruses, fungi, and other harmful agents.

The immune system has two main lines of defense including ²: 

• Non-specific immunity (Natural resistance):

The body is born equipped with a natural defense system, also known as innate immunity, which acts as a first line of defense against pathogens. Where does this “shield” come from and how does it work?

First is the physical and chemical barrier on the surface of the child’s body. The skin and mucous membranes (lining the respiratory, digestive, urinary tracts…) form a solid protective layer. The continuous secretion of sweat, tears, and mucus to wash away microorganisms. The acidic pH of the stomach becomes the “nemesis” of many bacteria and viruses through food. In addition, beneficial bacteria residing on the skin and mucous membranes also compete for adhesion sites, preventing the growth of pathogenic bacteria.

Next is the cellular barrier. Once the pathogen has passed the first layer of defense, the white blood cell “warriors” takes action. Neutrophils and macrophages act as patrolling “bodyguards”, quickly “swallowing” and digesting bacteria and viruses. Natural killer (NK) cells specialize in “hunting” and destroying cells in the body that have been invaded by viruses.

Finally, there is the humoral barrier, which consists of proteins and molecules dissolved in blood and body fluids. Natural antibodies, complement, and propecdin work together to lyse or neutralize bacteria and viruses. Interferons are secreted by cells to prevent viral replication inside cells.

All these barriers work continuously and in harmony, creating a strong natural resistance system, protecting the body from countless pathogens every day.

• Specific immunity (adaptive immunity):

In addition to the innate “shield”, the child’s body also possesses a second, more sophisticated and powerful defense system, called specific immunity (or adaptive immunity). This system is not available from birth but is formed after the child’s body is exposed to a specific pathogen (through natural illness) or by vaccination.

The outstanding feature of specific immunity is “memory”. When encountering the same pathogen that has been exposed, this system will react faster, stronger and more effectively. Specific immunity works through two main “armies” as follows:

• Humoral immunity: This “army” is in charge of B lymphocytes, with the main “weapon” being antibodies. Antibodies circulate in the blood and body fluids, with the ability to recognize and specifically bind to pathogens. They work in many ways such as preventing microorganisms from adhering to cells, neutralizing toxins, dissolving or agglutinating microorganisms, then “marking” them so that other immune cells can easily destroy them.
• Cellular immunity: This “army” is commanded by T lymphocytes. Helper T lymphocytes (T CD4) act as “commanders in chief”, coordinating and activating other immune cells. Cytotoxic T lymphocytes (T CD8) are professional “killers”, capable of recognizing and directly destroying body cells that have been invaded by viruses or intracellular bacteria.

Thanks to the coordination of these two “armies”, the specific immune system creates a strong protective barrier, allowing the body to effectively fight complex infections and remember to prevent re-infection.

2. Why do children get sick easily during the changing seasons?

There are many factors that make children more susceptible to minor illnesses during the changing seasons than adults, mainly due to the following reasons:

• Weak immune system: The immune system of children, especially children under 3 years old, not fully developed in terms of both the number and function of immune cells.
• Incomplete digestive system: Immature digestive system does not produce enough enzymes for children to digest food and the intestinal microflora is not balanced. This affects the ability to absorb nutrients and is the cause of a weakened immune system.

A healthy digestive system strengthens children’s  immunity

• The overuse of antibiotics, especially in young children, can cause drug resistance, destroying beneficial intestinal bacteria, leading to digestive disorders and immune deficiency. The vicious cycle of “sickness – antibiotics – digestive system effects – immune deficiency – illness…” is a worrying problem.
• Little exposure to disease sources (in some cases): Overly meticulous care and little exposure to the outside environment may cause the child’s immune system to not have a chance to “practice” and become weak.
• Other immune disorders: Some children may have congenital or acquired immunodeficiencies, which make them more susceptible to infections.

Once the immune system is weakened and not strong enough to fight pathogens, the child may face many serious consequences, affecting their health and overall development. Specifically: Children are susceptible to infections such as respiratory infections (flu, sore throat, bronchitis, pneumonia, etc.), digestive infections (diarrhea, vomiting, etc.) or other dangerous infectious diseases (measles, hand, foot and mouth disease, chickenpox, etc.). At the same time, children are also more susceptible to malnutrition and illness. Frequent illness causes children to lose their appetite and absorb poorly, leading to nutritional deficiencies, slow weight gain, and slow height development. In addition to the changing seasons, parents need to pay special attention to strengthening their children’s immune systems in the following stages:

• Going to kindergarten for the first time: The nursery and kindergarten environment is where children come into contact with many friends, which means they come into contact with more types of viruses and bacteria.
• During epidemic season: When there is an outbreak of disease (flu, measles, hand, foot, and mouth disease…), the risk of infection increases, it is necessary to strengthen preventive measures, including strengthening the immune system.
• Post-illness stage: The child’s body is still weak, the immune system is weakened and needs time to recover.

Strengthening resistance and improving the immune system is not only a “firefighting” measure when children are sick, but also a solid foundation for children’s comprehensive development in both physical and intellectual aspects.

3. Nutrition – A solid foundation for a healthy immune system

Nutrition – the foundation for a healthy immune system

The key role of nutrition in health, especially the immune system of children, cannot be denied. Nutrition not only provides energy for life activities but is also an essential “raw material” to build, maintain, and strengthen the “barrier” that protects the body from disease.

The relationship between nutrition and the immune system is a two-way, mutual relationship. Nutrition directly affects the development and function of the immune system, specifically as follows:

• Nutrition provides “building materials” for the immune system: Immune cells (such as white blood cells, antibodies) are made up of proteins and lipids. A lack of these nutrients weakens the body’s “army” of defense.

• Nutrition helps increase the production of immune cells: Adequate and balanced nutrition promotes the production of immune cells, antibodies, and other protective factors.
• Nutrition can improve immune system function: Nutrients such as vitamin C, vitamin D, zinc, selenium… enhance the ability of immune cells to recognize, attack, and destroy pathogens⁴.
• Nutritional support for reducing inflammation: Certain nutrients, especially omega-3 fatty acids, with anti-inflammatory properties supports the control of excessive inflammatory responses that can harm the body.

Insufficient supplement of necessary nutrients may weaken the immune system will, leading to serious consequences such as reduced quantity and quality of immune cells, making the body vulnerable to attack by pathogens; Reduced antibody production reduces the body’s ability to fight disease; Immune cell dysfunction: Immune cells function poorly, unable to protect the body in the best way.

4. Strengthen children’s resistance with scientific nutrition

To “upgrade” the immune system for children to fight diseases, especially during the changing seasons, parents need to pay special attention to their diet. Below are some “golden” tips to be applied at once.

Provide adequate protein

Protein – the ‘building block’ for constructing immune cells in children

Proteins contribute to the building of cells and tissues in the body, including immune cells (such as white blood cells, antibodies). Proteins are also involved in the production of important enzymes and hormones that affect the functioning of the immune system. A study by Li et al. (2007) in British Journal of Nutrition ⁵ has shown that protein deficiency can impair the number and function of T lymphocytes, an important type of white blood cell in the immune system. 

Children’s protein needs vary according to age and weight. According to recommendations of the National Institute of Nutrition of Vietnam⁶, Protein needs for children are as follows::

• Children 1-3 years old: About 13g protein/day.

• Children 4-8 years old: About 19g protein/day.

• Children 9-13 years old: About 34g protein/day.

To supplement protein for children, parents should increase the protein-rich foods below.:

• Animal sources: Meat (chicken, beef, lean pork), fish (salmon, mackerel, tuna…), eggs, milk and dairy products (cheese, yogurt).

• Plant sources: Beans (soybeans, green beans, black beans, peas…), nuts (almonds, walnuts, cashews…), whole grains (oats, quinoa).

Full vitamin and mineral supplement

Vitamins and minerals are essential micronutrients that play important roles in many biochemical processes in the body, including the functioning of the immune system.

• Vitamin A

Vitamin A is known to maintain the integrity of the respiratory and digestive tract mucosa and support the growth and differentiation of immune cells⁷.

Good sources of vitamin A for children that parents should refer to: liver, egg yolks, milk, yellow/orange/red vegetables and fruits (carrots, pumpkin, papaya, mango…) and dark green vegetables.

• Vitamin C

Vitamin C is a powerful antioxidant that protects immune cells from damage caused by free radicals and supports the function of cells, especially white blood cells.⁸

Vitamin C is abundant in citrus fruits (oranges, lemons, grapefruits, tangerines…), guava, kiwi, strawberries, bell peppers, broccoli and spinach.

• Vitamin D

The important role of vitamin D is to regulate the activity of the immune system, reduce the risk of respiratory infections, and reduce excessive inflammatory responses.⁹

Vitamin D is mainly found in sunlight with direct exposure of 15-20 minutes/day. In addition, it is also abundant in foods such as fatty fish (salmon, mackerel, herring…), egg yolks, mushrooms and milk.

• Vitamin E

Vitamin E is an antioxidant that protects cell membranes from damage and supports cell function, supports and strenghthens children’s immune system.¹⁰

Natural sources of vitamin E are often found in vegetable oils such as sunflower oil, soybean oil, olive oil…, nuts (almonds, sunflower seeds…), green vegetables and avocados.

• Iron

Iron is a mineral needed for the synthesis of hemoglobin, which carries oxygen in the blood and supports the function of immune cells. Iron deficiency can impair immune function and increase the risk of infection.¹¹

To supplement iron for children, parents should increase foods such as red meat (beef, pork), liver, egg yolks, and dark green vegetables (spinach, kale…).

• Zinc

Zinc is involved in the development and function of immune cells, especially T lymphocytes and macrophages. Zinc deficiency can impair immune function, increase the risk of infection and slow wound healing.¹²

Zinc comes mainly from foods such as seafood (oysters, shrimp, crab), red meat, poultry, nuts, whole grains, milk, and dairy products.

• Selen

Selenium is known as an antioxidant, protecting immune cells from damage and supporting the function of antioxidant enzymes in the body.¹³

In food, selenium is abundant in seafood (tuna, mackerel, shrimp…), meat, eggs and mushrooms.

Increase intestinal probiotics

Probiotics not only balances the intestinal microflora, inhibits the growth of harmful bacteria, but also supports the digestive tract’s ability to absorb micronutrients. Thereby indirectly enhancing the health of children’s natural immune system.¹⁴

Parents can increase their child’s intestinal bacteria by supplementing foods such as yogurt or naturally fermented foods such as natto, miso or soy tempeh.

Supplement Prebiotics

Fiber, especially soluble fiber (prebiotics), is “food” for beneficial gut bacteria, allowing them to grow and function better. Fiber also helps maintain intestinal health, preventing constipation and other digestive diseases.¹⁵ And in young children, 70-80% of immune cells are located in the small intestine. These immune cells in the small intestine play an important role in recognizing and responding to antigens from the digestive tract.

Therefore, supplementing enough fiber indirectly help children strengthen their immune system. Soluble fiber is abundant in foods such as oats, beans, apples, pears, citrus fruits, green vegetables (broccoli, spinach, cauliflower…), whole grains.

To comprehensively strengthen children’s immune systems, in addition to a balanced diet, supplementing with supportive products is necessary, especially during the changing seasons or when children are at high risk of disease. ColosCare 24h is a nutritional solution researched and developed by Nutricare and the Nutricare Medical Nutrition Institute – USA (NMNI-USA). The product has a specially designed formula to support increased resistance, effectively reduce minor illnesses with a superior IgG antibody content of 1200 mg from 24h Colostrum imported from the US. The product provides up to 10 billion probiotics, including Bifidobacterium and Lactobacillus strains, along with soluble fiber (FOS/Inulin) and HMO, creating a favorable environment for probiotics to grow, supporting children to absorb well, reducing constipation. Along with that, ColosCare 24h provides easily absorbed Protein, Calcium, Vitamin D3 to help children grow taller and gain weight exceptionally well. 

A healthy immune system is the “golden key” to a child’s overall health and development. Nutrition plays a fundamental role, especially essential vitamins, minerals, and intestinal probiotics. By applying evidence-based nutrition principles and fostering a balanced diet, parents can strengthen their child’s immune system, reduce illness risks, and support optimal growth for a healthier future. Let’s begin the journey of nurturing your child’s health today.