Minerals For the Immune System

Introduction

In the intricate relationship between health and wellness, the body’s immune system stands as the loyal guardian, tirelessly defending us against threats. Our immune system’s effectiveness relies on several factors, including lifestyle, genetics, and most significantly, nutrition. Generally, a balanced diet is sufficient to provide the body with the essential minerals and vitamins. 

Nevertheless, some groups of people are at an increased risk of mineral/ vitamin deficiency due to chronic illness, age (elderly), pregnancy, dietary style (Vegetarians or vegans), or lifestyle (athletes). For these groups of people, a qualified nutritionist should decide on the appropriate diet or supplementation required to achieve adequate levels of the essential and non-essential minerals without experiencing any side effects or having any drug interactions.¹

Overview of the immune system

The immune system consists of two parts: innate and acquired. The innate immune response is the first reaction to an infection. It is quick but not specialised. The innate immune response consists of three protection mechanisms: physical barriers, cellular components, and humoral responses.^2,3 

Innate immune response

Physical barriers form the first line of defence and include body surfaces such as the mucus membranes and the skin) which form chemical and physical barriers against pathogens.

Cellular components are the second line of defence that include phagocytes, interferons (IFNs), and Natural Killer (NK) cells. Phagocytes digest microbes, producing reactive oxygen species (ROS) in the process. Interferons are antimicrobial agents that inhibit pathogen growth, while NK cells kill pathogens via cytotoxins (substances that have toxic effects on cells). 

Neutrophils and NK cells produce antimicrobial peptides such as cathelicidins, which absorb and kill bacteria. Neutrophils and macrophages migrate to the infected area, where neutrophils kill the infection and macrophages clear the cellular waste.^2,3

Acquired immune response

Also called obtained immunity, is dependent on the ability of the immune cells to differentiate between their own cells and unwanted invaders. It is the defence we gain through life after facing numerous illnesses or receiving vaccinations. This defence includes the production of antibodies that recognize specific antigens present in the pathogens and, hence, exert the appropriate immune response. 

Acquired immunity response takes longer time than innate immunity. It takes about 5-10 days to produce antibodies, during which innate immunity acts aggressively to conserve the levels of pathogens.^2,3

When provoked by specific offensive agents, acquired immunity can initiate operations (slower than producing antibodies) that use B and T cells. There are three types of T cells:

• Cytotoxic CD8+ T cells kill pathogens after identification of peptide antigens on the pathogen's membrane
• CD4+ T helper (Th) cells help B cells and other T cells accomplish their function
• Regulatory T cells (Tregs) prevent excessive immune reactions ^2,3

The cells further differentiate into Th1 and Th2 cells, where:

• Th1 cells secretes interleukin – 2 (IL-2) and IFNγ
• Th2 cells also produce several other interleukins, ILs (IL-4, IL-5, IL-10, and IL-13) against pathogens^2,3

Interleukins are a type of cytokines that are produced by many body cells and play a role in the activation and differentiation of immune cells such as proliferation, maturation, migration, and adhesion.^2,3

Nutrient effect on the immune system

Micronutrients such as minerals and vitamins are an integral part of a diet effective in eliminating diseases and improving quality of life. The optimal amounts of these nutrients vary at the different stages of a person’s life. Lack of micronutrients weakens the body’s immune system and makes it more susceptible to infections and diseases.

Nutrients interact with the immune system in four steps, where the first 2 steps are the inactive steps that have to do with the provision of nutrients. The third and fourth are the active steps that play a role in regulating the immune response.²

• Step 1 involves the provision of nutrients such as proteins, vitamins (A, E, and C), and minerals (Zinc and Iron)
• Step 2 involves the supply of glutamine, a standard fuel for the body’s immune cells, especially during strenuous exercise
• Step 3 allows dynamic communication with the body’s defence system to control its function to the desired goal
• Step 4 inspects the relationship between diet, environment, and genome²

It's evident that micronutrients are crucial components of the immune system, and maintaining optimal levels is essential for its effective functioning. Each phase of the immune response depends on specific micronutrients being present. Vitamins A, D, C, E, and zinc are needed for the structural and functional integrity of the internal and external body surfaces. 

The cell-mediated processes within the innate immune response, encompassing cell proliferation, differentiation, function, movement, and the capacity to initiate oxidative bursts, depend on sufficient levels of vitamins A, D, C, E, B6, and B12, as well as folate, iron, zinc, copper, selenium, and magnesium. The link between innate and adaptive immunity is connected through the inflammatory response, which is modulated by vitamins A, C, E, and B6, along with iron, zinc, and copper.

Adaptive immune response, including cell-mediated and humoral immunity, depends on the presence of various micronutrients throughout all stages (lymphocyte proliferation, differentiation, and function, and humoral- and cell-mediated immune processes). Moreover, these micronutrients are involved in:

• The Self-protection of immune cells (via antioxidant mechanisms, e.g. vitamins C and E, zinc, iron, magnesium, copper, and selenium)
• Inhibitory actions (vitamins D, B6 and E)
• Elimination of spent cells via apoptosis and clearance (limiting tissue damage, e.g. vitamin C)³

Essential minerals

Several minerals play important roles in supporting the immune system’s function. Some of the essential minerals that are known to have positive effects on the immune system are:

Zinc

Zinc is essential for the normal development and function of immune cells. Plays a crucial role in the production of antibodies as well as helps in wound healing and maintaining the skin and mucous membrane integrity. Zinc improves the function of phagocytes by modulating oxidative explosion activity. 

Moreover, zinc is involved in improving Th1 function. Furthermore, zinc has antioxidants that protect against reactive oxygen species (ROS), produced when phagocytes digest microbes.

Foods that are rich in zinc include meat, fish, poultry, and soy. The recommended daily amount of Zinc is 8 mg for women and 11 mg for adult men.^4,5

Selenium 

Selenium acts as a regulator of cellular antioxidants and is therefore effective for the function of leukocytes. Helps in supporting the immune system by increasing the production of IFNγ. It is also an essential component of antioxidants called selenoproteins which are necessary for the NK cell, macrophage, neutrophil, and T lymphocyte functions. 

The recommended daily allowance of selenium is 55 micrograms per day, for adults aged 19 and above. Whereas pregnant and breastfeeding women need between 60 -70 micrograms per day, respectively. Selenium can be obtained when eating seafood, offal, meat, and poultry.^4,5

Iron

Iron is an essential mineral required by all living organisms and is involved in a variety of biological processes. Iron supports the production and function of many immune cells like interferon IFNγ, macrophages, cytokines, lymphocytes, CD4+ cells, and CD8+ cells. Moreover, iron is important in the differentiation and growth of epithelial tissue.

The average daily allowance of iron differs between different age groups as well as gender.

For children, it is (13.7-15.1 mg), for teenagers (16.3 mg), for men (19.3-20.5 mg), and for women above 19 years of age (17.0-18.9 mg). Both overabundance and deficiency may result in detrimental effects not only on the immune system but on a range of other body cells, tissues and organs. Foods that are rich in Iron include beans, spinach, liver, chicken breast, peanuts, beef, potatoes, eggs, and broccoli.^4,5

Copper

Copper is an essential element with an important role as a free radical hunter that preserves the intracellular antioxidant equilibrium. It is also important for the normal functioning of macrophages, monocytes, neutrophils, and NK cells.

Can be obtained from eating chocolates, nuts, legumes, cereals, and dried fruits. The daily dietary requirement for adults is 900 micrograms.^4,5

Magnesium

Magnesium controls leukocyte activation and is involved in the control of apoptosis. Magnesium deficiency increases the ability of macrophages to produce inflammatory cytokines, resulting in inflammation. Magnesium can be obtained while eating seeds, kernels, legumes, grains, green vegetables, and milk. Magnesium’s daily dietary requirement is 310-320 mg for women, while for men, it is 400-420 mg.^4,5

Iodine

Iodine regulates the immune system by improving immunity control and fighting infection. For example, by assisting in the removal of chemical and biological toxins or suppressing the autoimmune response. Iodine deficiency leads to disruptions in the antioxidant system and hence immunodeficiency and cancer development.

The daily iodine allowance is 150 micrograms for men and non-pregnant females, whereas, for pregnant women, a daily dose of 220 to 250 micrograms is suggested, and 250-290 micrograms for breastfeeding mothers.^4,5 

Summary

It is always better to prevent rather than cure. Therefore, the best approach to protect ourselves from microbial attacks and infections is to boost our immune system. This can be done by following a diet that is rich in the essential nutrients and vitamins that play a vital role in the production and maintenance of the immune cells.

However, only trace amounts are required, therefore, it is important to not take more than the assigned amount as overconsumption has its own bad consequences. The underlying mechanism of action of the nutrients, especially in diseased conditions, remains uncertain. Further studies are required to establish the optimal vitamin and mineral dosage supplementation to promote immune health.