Adequate Vitamin D Intake Protects Us From COVID-19 Virus.

ROLE OF VITAMIN D IN COVID-19 INFECTIONS
Modern humans, with adequate Vitamin D blood levels, are able to resist infections caused by Microorganisms.

Vitamin D induces White Blood Cells (WBCs) and Epithelial cells to produce Antimicrobial Peptides known as Host Defense Proteins (HDPs)

The HDPs (defensins, and cathelicidin.) are found in many body fluids.

Functions of HDPs
HDPs help WBCs to kill invading microorganisms like Bacteria, Viruses, Fungi, Parasites.

HDPs reduce Viral replication rates.
HDPs also help to kill off Cancer Cells.
HDPs attract White Blood Cells (WBCs) to the sites of pathogen-invasion.

HDPs signal to WBCs to switch-off the production of Antibodies and Pro-Inflammatory cytokines.

WHITE BLOOD CELLS (WBC)
The White Blood Cells (WBCs) do have Vitamin D receptors on their surfaces; that means Vitamin D influences the metabolic activities of WBCs.

CYTOKINES
Cytokines are proteins produced and secreted by Activated Phagocytes. (PMNs, Macrophages)

Cytokines help with cell-to-cell communications.
Phagocytes do have Vitamin D receptors.
Vitamin D restricts the production and release of the Pro-Inflammatory Cytokines (IL-1, IL-6, IL-8, IL-8, IL-12, TNF)

These inflammatory Cytokines, released by the WBCs as they tackle pathogens, are harmful to Normal Body Tissues.

When large amounts of these Pro-Inflammatory Cytokines are released, they initiate severe inflammatory reactions, locally and systemically, leading to various Tissues, Vascular, and Organs injury.

In the lungs, for example, the release of Inflammatory Cytokines after COVID-19 viruses gain entry into the Respiratory Epithelium, leads to severe inflammation, and the subsequent vasodilatation, and leakage of blood (fluids and RBCs) from the Lung Arterioles into the Alveolar Sacs. This causes Ventilation-Perfusion problems that lead to Low Oxygenation, Pneumonia, ARDS and eventual Respiratory Failure.

Nature balances the equation. To counteract the Pro-Inflammatory Cytokines, nature has provided us with the Anti-Inflammatory Cytokines

Vitamin D induces the production of the Anti-inflammatory cytokines (IL-4, IL-10, IL-11, IL-13) in Activated Phagocytes.

VITAMIN D
The WBCs have Vitamin D Receptors on their surfaces.

Vitamin D induces the synthesis of HDPs, and the Anti-inflammatory cytokines.

Vitamin D promotes the Anti-Tumoral Activities of WBCs.

Vitamin D inhibits the production of the Pro-inflammatory cytokines by Activated Macrophages.

Vitamin D ensures that inflammations do not get out of control, it does so by inducing the production of more of the HDPs by WBCs, and epithelial tissues.

INADEQUATE VITAMIN D LEVELS HAVE BEEN ASSOCIATED WITH INCREASED RISK FOR SEVERE INFLAMMATIONS, AND SEPSIS, following infections caused by viruses, (including the COVID-19) and other pathogens.

Human Populations with low Vitamin D levels experience more fatalities from the COVID-19 infections than populations with adequate Vitamin D Blood levels.

COVID-19 VIRUS.
In the absence of adequate levels of Vitamin D, and the HDPs, the COVID-19 Virus causes the release of more Inflammatory Cytokines (mainly IL1, IL6, IL12, and TNF-alpha) locally and systemically.

In the respiratory tract, the release of uncontrolled amounts of inflammatory cytokines causes Red blood cells and fluids to escape from the blood vessels, and flood the alveolar sacs (airspaces in the lung) this leads to ventilation and perfusion problems and eventual respiratory failure.

Vitamin D and the HDPs restrict the release of the inflammatory cytokines from WBCs, thus, Vitamin D protects the Lungs from Severe Inflammation and Lung injury.

RISK FACTORS FOR VITAMIN D DEFICIENCY
. Body Mass Index greater than 30. Excessive fat dilutes the vitamin D concentration in the body.

. Ageing and the aged: Old skin are less efficient in vitamin D photosynthesis.

. Inadequate exposure to sunlight.
. Kidney and Liver diseases. (N.B Active vitamin D is produced in these organs)

. Naturally dark skin tone
. Smoking
. Using sunscreen creams and lotions
. Wearing sunscreen clothes.
Dark-skinned individuals have high level of melanin which acts as a sunscreen to impair vitamin D photosynthesis.

In North America and Europe, and other temperate countries vitamin D deficiency is more common in Blacks than in Caucasians.

African Immigrants in temperate climates, need to monitor their vitamin D levels annually.

The use of sunscreens completely blocks photosynthesis of vitamin D and reduces circulating vitamin D levels.

SOURCES OF VITAMIN D
Humans obtain vitamin D from 3 sources:
. UV-B sunlight exposure
. Diet
. Vitamin D3 supplements.
The only way to know if one has adequate vitamin D level, is to measure 25(OH)D blood concentration.

Include naturally, vitamin-D-rich foods, example Fatty Fish such as Salmon, Trout, Sword fish and Tuna, Eggs, Mushroom, in your diet,

Dietary supplements:
Vitamin D3 5000 IU daily to achieve a targeted blood level of 25(OH)D >40-60ng/ml

ALEX SARKODIE, MD