How To Boost Immune System?

The immune system functions as the armor of the human body. The immune system protects the body from harmful pathogens. The human cells and metabolic pathways are under constant surveillance by the immune system so that an individual can remain healthy and function normally. A disease occurs when the immune system is not functioning normally and may lead to detrimental effects on the health. Micronutrients including vitamins and minerals are among numerous nutritional components that can strengthen the immune system and promote the overall health of an individual.

Immunomodulatory Effects of  Vitamin D3 and K2 MK-7
Vitamin D is also called the sunshine vitamin. Humans synthesize vitamin D on exposure to the sun and may also obtain vitamin D from dietary sources. The active form of vitamin D, also known as vitamin D3, calcitriol, or cholecalciferol, is responsible for the therapeutic and physiological benefits of vitamin D3. Approximately 50% of the global population suffers from vitamin D deficiency owing to lifestyle modifications and environmental factors. Therefore, vitamin D supplementation can protect an individual from the clinical consequences of vitamin D deficiency.

Vitamin D3 supplementation plays a crucial role in modulating the immune system. The T cells of the immune system have a relatively greater number of receptors for vitamin D3. The immune cells also acquire enzymes that are involved in the conversion and formation of active forms of vitamin D3. Vitamin D3 promotes the production and release of IL-10, a cytokine that has anti-inflammatory and immunoregulating properties. Vitamin D3 suppresses the activity of helper T cells, Th17 cells, and leads to a subsequent reduction in the levels of pro-inflammatory cytokines including IL-17 and tumor necrosis factor-alpha (TNF-alpha). Vitamin D3 also reduces Th1 and Th9 cytokines. This regulates the inflammatory processes in an individual.

Apart from significant anti-inflammatory effects, vitamin D3 inhibits cellular proliferation and suppresses the formation of newer blood vessels. Vitamin D3 also has protective properties against autoimmune disorders including multiple sclerosis, autoimmune thyroid disease, and rheumatoid arthritis. Vitamin D3 inhibits the production and release of proinflammatory cytokines including IL-6, IL-8, IL-1-beta, and prostaglandin E2. Vitamin D3 also inhibits the activity of Th1 lymphocytes. On the contrary, regulatory T cells, IL-4, and transforming growth factor-beta 1 (TGF-beta 1) are seen to increase. Individuals with a greater concentration of vitamin D3 are less susceptible to developing these autoimmune disorders.

Vitamin D3 supplementation is often complicated by the onset of hypercalcemia or increased plasma levels of calcium. The long-term complications of vitamin D3 toxicity include osteoporosis, vascular calcification, and kidney stones. The hypercalcemic effects of vitamin D3 occur due to deficiency of vitamin K2, also called menaquinone or MK-7. In the absence of vitamin K2, the bones do not absorb calcium effectively resulting in osteoporosis and the excessive calcium manifests as kidney stones and vascular deposits. Vitamin K2 carboxylates and activates osteocalcin, a gamma-carboxy glutamic acid-containing, and calcium-binding protein. Osteocalcin leads to effective calcium deposition in the bone.

Immunomodulatory Effects of  Vitamin C and Zinc
Similar to other micronutrients, humans can not synthesize vitamin C and zinc, thus, they shall obtain these micronutrients from exogenous sources including foods and supplements. Vitamin C, also called ascorbic acid, is an essential micronutrient required by the body for normal metabolic reactions. Ascorbic acid serves as a cofactor for enzymes that are involved in the production of neurotransmitters, collagen, and carnitine. The antioxidant effects of vitamin C reduce the cytochromes, oxygen, and iron as well as spare glutathione which serves as an intracellular antioxidant enzyme. Zinc is also an important micronutrient in the human body. The functions of zinc can be divided into structural, catalytic, and regulatory categories. Zinc plays an important role in defending the normal body tissues against free radicals and reactive oxygen species as well as regulating the immune system to maintain optimal health and wellbeing of an individual. The deficiency of either or both vitamin C and zinc makes an individual prone to different diseases, cancer, and other immune disorders.

Zinc and vitamin C have complementary roles in modulating and strengthening the immune system of an individual. Both zinc and vitamin C stabilize the epithelial barrier, an important component of innate immunity. While vitamin C stimulates collagen synthesis, zinc stabilizes the strengthens the epithelial barrier by inducing cellular proliferation and increasing the thickness of the epithelial and the mucosal barriers. Zinc and vitamin C also influence the cellular components of innate immunity, particularly the ones involved in the phagocytosis process. Vitamin C mobilizes the neutrophils and monocytes while the antioxidant activity of vitamin C regulates the levels of free radicals and reactive oxygen species.
Concerning adaptive immunity, zinc plays a more significant role than vitamin C. Zinc promotes the formation of B and T lymphocytes from the bone marrow stem cells. Moreover, zinc promotes the differentiation of B and T lymphocytes as well as the effective function of T cells and B cells including adequate antibody response. Zinc mediates the balance between Th1 and Th2 cells, and prevents imbalance between the two helper T cells, thus, regulating the immune response. Zinc is also necessary for effective interaction between the T and B lymphocytes resulting in effective immune function. zinc mediates the destruction of cancerous cells or tumors and infected tissue cells. Hence, both zinc and vitamin C play a significant role in modulating the immune system to protect the body against harmful pathogens and cancerous changes in the tissues.

Conclusion
This article discusses the role of vitamin C, vitamin D3, vitamin K2, and zinc in modulating immune function and promoting the overall health of an individual. The synergistic action of zinc and vitamin C strengthens the innate and adaptive immune systems. Zinc and vitamin C strengthen the mucosal and skin barriers, improve phagocytosis, and stimulate the production and function of T and B lymphocytes. Similarly, vitamin D3 and vitamin K2 have immunomodulatory effects. Vitamin D3 promotes the release of anti-inflammatory cytokines and suppresses the production and release of proinflammatory cytokines. Concomitant intake of vitamin K2 protects the individual from hypercalcemic effects of vitamin D3 supplementation by promoting calcium deposition in bones.

References
1. https://www.ncbi.nlm.nih.gov/books/NBK279364/
2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3356951/
3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7281985/
4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7406600/
5. https://journals.sagepub.com/doi/pdf/10.1177/147323001003800203