Immunity is the body’s ability to fight infection and disease, and proper nutrition can support and enhance this ability. The impact of nutrition on immunity is complex and comprehensive, and a healthy lifestyle in general is key to maintaining a strong immune system. Therefore, it is worthwhile to ensure a balanced and varied diet, avoid excessive stress, keep physically active and regularly check your health.

Proper nutrition provides the body with essential nutrients such as vitamins, minerals, proteins and fats, which are necessary for the immune system to function properly.

Both excess and deficient intake of food can affect the functioning of the immune system. Excessive food intake and obesity can lead to chronic inflammation, which carries metabolic consequences and further complications, and weakens immunity.  The severe effects of obesity carry the risk of diseases such as non-alcoholic fatty liver disease, sleep apnoea or increased risk of atherosclerosis.

On the other hand, energy deficiency can weaken the functioning of the immune system. Malnutrition broadly weakens the body’s defence mechanisms, resulting in an increased susceptibility to and more severe course of infections. Protein-calorie malnutrition affects all types of immunity. It impairs both innate immunity and acquired immune mechanisms.

The role of hydration

Water has many functions in the body: it enters into the composition of all cells and tissues, enables the transport of nutrients and metabolic products, cools us in hot weather, escaping to the surface of the skin as sweat, and protects various organs, e.g. the brain, spinal cord, eyeball from damage. It is essential for proper digestion.

Insufficient fluid intake leads to dehydration, which results in disorders of the whole body. The first symptoms of dehydration are a feeling of fatigue, headaches and dizziness, general weakness, overheating of the body.

The World Health Organisation recommends that we drink 30 ml of water per kilogram of body weight per day. According to the Nutrition Standards for the Polish population, a sufficient intake of water from beverages and food products for children and adolescents is 1.25-2.5 litres, depending on age and sex.


Carbohydrates provide the body with energy, which is essential for the functioning of the immune system. Immune cells need energy to perform their functions, such as destroying pathogens. Carbohydrates are important structures that enable the immune system to function. The ability of the immune system to use these molecules as specific antigens is undeniable.

Adequate carbohydrate intake helps to maintain the body’s energy balance. Carbohydrates in the form of dietary fibre, which is found in fruit, vegetables and whole grain cereal products, play an important role in maintaining a healthy gut microbiota. The gut microbiota is crucial for immune system health. Consuming carbohydrates with a low glycaemic index and load can help regulate inflammatory processes in the body, which has an impact on immune function.

The role of polyunsaturated fatty acids in the diet

Polyunsaturated fatty acids are a type of fatty acid that have many important effects on human health. In particular, the two main types of polyunsaturated fatty acids are linoleic acid (omega-6) and alpha-linolenic acid (omega-3). They are essential components of a balanced and healthy diet. The most important sources of PFAs in the diet are vegetable oils. Low-acid rapeseed oil contains approximately 30% linoleic acid and 14% α-linolenic acid. A high content of α-linolenic acid is found in linseed oil with 60%. Eicosapentaenoic and docosahexaenoic acids, which belong to the ω-3 family, are synthesised by phytoplankton serving as food for fish. EPA and DHA are stored in the muscles and liver of marine fish and are therefore the primary source of fatty acids of the ω-3 family.

Regular consumption of these acids may help to lower LDL cholesterol (bad cholesterol) and reduce the risk of heart disease, including coronary heart disease. Omega-3 and other polyunsaturated fatty acids have anti-inflammatory properties. They help reduce inflammation in the body and can be beneficial in the treatment of inflammatory diseases. They also play a key role in brain development and nervous system function.

Vitamin C

Vitamin C deficiency can lead to a condition known as scurvy, which is characterised by symptoms such as muscle weakness, skin and gum problems and, in severe cases, can lead to serious health problems. It is therefore important to ensure an adequate amount of vitamin C in the diet. As vitamin C stored in leukocytes is quickly used up during infections, it is recommended that the supply of vitamin C is increased during autumn and winter by increasing the intake of vegetables and fruit.

Ascorbic acid protects tissues from damage by acting as an antioxidant on cell membrane lipids and by neutralising reactive oxygen species. Vitamin C has an immunostimulating effect. It influences the synthesis of prostaglandins, the intracellular pool of nucleotides, increases the production of cytokines, abolishes the immunosuppressive effect of histamine and improves iron assimilation.

Vitamin D

Vitamin D deficiency severely impairs the physiological balance of the body and can contribute to the development of many conditions including osteoporosis, increased risk of fractures, weakened immune system and other complications.

Vitamin D is essential for the proper absorption of calcium and phosphorus from the gastrointestinal tract, which is key to maintaining healthy bones and teeth. It plays an important role in regulating the immune system. It helps the body fight infection and inflammation.

Vitamin D is 20% supplied through food. Products containing the largest amounts are marine fish, mainly mackerel, salmon, herring and fish oils. Smaller amounts of vitamin D are present in meat, poultry, offal and dairy products.

Vitamin D2, on the other hand, is found in plant foods and mushrooms.Vitamin D is absorbed in the small intestine in the presence of fats. The majority of vitamin D is produced by metabolism in the skin. The best way to maintain adequate vitamin D levels is through supplementation.

Vitamin A

Vitamin A deficiency can lead to various health problems and have serious consequences for vision, growth and immunity; it is essential for metabolic processes. Vitamin A deficiency results in impaired immune system function and consequently increased incidence of infectious diseases and increased mortality.

Products rich in vitamin A are mainly animal products containing retinol, e.g. offal, eggs, butter, ripened cheese and certain species of marine fish. Provitamin A is mainly found in carrots, spinach, parsley, chard, red peppers, as well as peaches and apricots.

Vitamin E

Excess vitamin E in the body can be harmful, so the recommended doses of supplements should always be followed. Vitamin E can be provided from food and the main sources are vegetable oils (especially sunflower seed oil and soybean oil), nuts, seeds, green leafy vegetables and whole grain cereal products. The main role of vitamin E is to combat free radicals

Compounds belonging to the vitamin E group are mainly found in products of plant origin. Small amounts of α-tocopherol are found in fish and poultry and milk (0.5-10 mg/100 g). The richest sources of α-tocopherol are wheat germ oil (133 mg/100 g) and sunflower seeds (49 mg/100 g).


Nutritionally essential for humans, selenium is a component of more than twenty selenoproteins that play a key role in reproduction, thyroid hormone metabolism, DNA synthesis and protection against oxidative damage and infection.

Deficiency can also lead to muscle weakness and thyroid problems. Selenium deficiency is also linked to infertility in men and may play a role in Kashin-Beck disease – a type of osteoarthritis. Excess selenium is also harmful and can lead to poisoning.

Rich sources of selenium are foods with a high protein content. The element is found in offal, especially kidney, also seafood and fish. A good source of selenium is milk and milk products, as well as cereal products. Plants are a much smaller reservoir of selenium, with the exception of garlic and legumes, which contain more of it.


Zinc deficiency can lead to a number of health problems, such as a weakened immune system, growth retardation in children, skin problems, difficulty healing wounds, taste and smell disorders, and other symptoms such as fatigue and apathy.  Zinc has a direct effect on the production, maturation and function of leukocytes. However, excess zinc can also be harmful and lead to toxicity.

Its main sources are meat and meat products and cereal products. Foods rich in zinc include: dark bread, rennet cheeses, meat, liver and buckwheat groats.


Iron deficiency increases the risk of infections, infestations and also decreases bactericidal function. Iron is an essential component of enzymes necessary for oxidation processes and the proper function of immune cells.

One of the most important functions of iron is to participate in oxygen transport. Haemoglobin, a protein present in red blood cells, contains iron and is responsible for transporting oxygen from the lungs to tissues and organs.

Dietary sources of iron include red meat, poultry, fish, iron-enriched cereal products, nuts, seeds, eggs, leafy vegetables and legumes.


Antioxidants are essential nutrients found mainly in food and are needed in small amounts to maintain the body’s health. Antioxidants mainly play a role in reducing and controlling oxidative stress and fighting infectious diseases. Some antioxidants, such as vitamin C and vitamin E, have anti-inflammatory properties.

Antioxidants help to repair damaged cells in the immune system. This allows the body to fight off infections faster and more effectively. They protect the immune system and increase resistance to infectious microorganisms such as bacteria, viruses and parasites. It is strongly recommended to include antioxidants in the daily diet, as a lack of them can weaken the immune system and, as a result, its ability to defend the body against disease.

Examples of antioxidants include vitamin C, vitamin E, beta-carotene, selenium, flavonoids and polyphenols, which can be found in fruits, vegetables, nuts, seeds, herbs and spices. A healthy and balanced diet, rich in a variety of nutrients, is very important for strengthening the body’s immunity. The diet should include a variety of food groups, such as vegetables, fruit, whole-grain cereals, protein, healthy fats and dairy products.