Vitamins and their metabolites, as well as trace elements, are essential substances for a large number of physiological processes, fulfilling various functions as hormones and antioxidants. Research has shown that micronutrients are essential for immune function, especially vitamins A, C, D, E, B6, B12, folic acid, selenium and zinc.
The immune system
The immune system is divided into two types: the innate and the adaptive (that which is created during life). The innate is the first line of defense, it is fast and able to detect many common infectious agents, such as viruses and bacteria. It also provides the basis for the activation of the adaptive system through chemical signals (cytokines) or degraded products of infectious organisms (antigens). The adaptive system provides a special defense by distinguishing very subtle differences in the composition of infectious agents. However, it is slow and can take several days before its two main cell types are activated: B and T lymphocytes.
What are the vitamins that boost your immune system?
Vitamin A is important for the normal functioning of various types of immune cells of the innate response, including natural killer cells, macrophages and neutrophils. Most of the immune effects of vitamin A are made from its derivatives, isomers of retinoic acid. More than 500 genes are directly or indirectly regulated by retinoic acid .
Vitamin A supplements boost immunity and have been shown to reduce the morbidity and mortality associated with deficiency. A meta-analysis of 43 randomized controlled trials involving 215,633 children aged 6 months to 5 years found that vitamin A supplementation reduced the risk of all-cause mortality by 24% .
Vitamin A is found in dark green leafy vegetables, for example amaranth and spinach, carrots, pumpkin seeds, mango, eggs, liver, milk and some oils such as palm oil.
Similar to vitamin A, vitamin D regulates the expression of hundreds of genes. This is through its active form, 1,25-dihydroxyvitamin D3. Antimicrobial peptides (AMPs) and proteins are critical components of the innate immune system because they directly kill pathogens and especially bacteria. The active form of vitamin D regulates important antimicrobial proteins.
Vitamin D is found in fatty fish – salmon, sardines, herring and mackerel – in red meat, liver, egg yolks and fortified foods such as breakfast cereals.
Vitamin C helps increase defenses by supporting various cellular functions of both the innate and adaptive immune systems . It accumulates in phagocytic cells, such as neutrophils, and enhances phagocytosis, creating reactive oxygen species within these cells that are then used for microbial killing. Leukocytes, such as neutrophils and monocytes, accumulate vitamin C at values that are 50-100 times higher than its concentrations in the blood.
Vitamin C deficiency leads to reduced immunity and greater susceptibility to infections. Although the amount of vitamin C required to prevent scurvy is relatively low (10 mg / day), a diet providing 100–200 mg / day is necessary to saturate plasma concentrations in healthy individuals. Common foods that contain vitamin C are oranges, peppers (red and green), kiwis, strawberries, broccoli and mangoes.
Vitamin E is a fat-soluble antioxidant that protects the integrity of cell membranes. One form of it, α-tocopherol, protects against the peroxidation of polyunsaturated fatty acids, which can cause cell damage and lead to inappropriate immune responses . Α-Tocopherol enhances the T cell-mediated immune response, which decreases with age .
Vitamin E is mainly found in oils such as canola, sunflower oil, corn oil and olive oil. It is also found in almonds and in smaller quantities in avocados.
Folic acid is required as a coenzyme to mediate methyl transport (-CH3). This occurs in a variety of reactions that are critical to the endogenous synthesis and metabolism of nucleic acids (DNA and RNA) as well as amino acids. Animal studies and observational studies in humans have shown that folic acid deficiency is associated with increased susceptibility to infections .
Folic acid is found in broccoli, Brussels sprouts, spinach, peas, chickpeas, beans and liver.
Vitamin B12 is important for the synthesis of hemoglobin, the substance that carries oxygen to red blood cells. Patients diagnosed with vitamin B12 deficiency (megaloblastic anemia) have a reduced number of natural killer cells, a study has shown.
This was corrected by supplementing with vitamin B12  which is found in meat, fish, milk, eggs and fortified breakfast cereals.
Vitamin B6 is required for the endogenous synthesis and metabolism of amino acids, cytokines and antibodies. Animal and human studies have shown that vitamin B6 deficiency affects aspects of adaptive immunity.
B6 is found in chicken and cold water fish such as salmon and tuna, green vegetables and oats.
Zinc is critical for the growth and function of cells mediating both innate and adaptive immunity . Even a borderline zinc deficiency can suppress aspects of immunity.
It is found in meat, shellfish, dairy products such as cheese, and cereals.
Adequate selenium intake is essential for the proper immune response because it is required for the function of various selenium-dependent enzymes, known as selenoproteins. Selenium deficiency impairs aspects of innate and adaptive immunity.
Selenium is found in Brazilian pistachios, fish, meat and eggs.
At Vita4you.gr you will find a variety of multivitamin supplements!
- Gene expression regulation by retinoic acid.
- Vitamin A supplements for preventing mortality, illness, and blindness in children aged under 5: systematic review and meta-analysis.
- Vitamin C and Immune Function.
- Vitamin E and immunity.
- Age-associated changes in immune function: impact of vitamin E intervention and the underlying mechanisms.
- Folate status and the immune system.
- Effects of cyanocobalamin on immunity in patients with pernicious anemia.
- Zinc in human health: effect of zinc on immune cell.