Introduction

Vitamin-D is a fat-soluble micronutrient that is more like a hormone as it is:

  • Synthesised by an organ (skin using Cholesterol + UVB)
  • Travels via bloodstream to target organs
  • Highly specific receptors (Vitamin D Receptor) that initiate their effects via gene transcription

Roles of Vit-D:

  • Bone & Calcium absorption
  • Muscle growth
  • Immune function
  • Brain mood
  • Blood vessel elasticity

Sources of Vit-D include:
Sun, Salmon, Mushrooms, Eggs, Fortified cereals and milk

Calcium & Phosphorus Absorption

In intestine cells, Vit-D helps transcribe genes that create transporters that help Calcium and Phosphorus ions from the food we consume into the blood stream.

Bone Maintenance

Strong bones need to be continuously remodeled for structural repair and stress adaptation (frequent in sports).

Vit-D helps transcribe genes that help mature the two key cells in this process:

  • Osteoclasts - Breakdown old or damaged bone with controlled enzymes and acids
  • Osteoblasts - Build new bone using Phosphorus, Calcium and Vit-K

Muscle Growth

Vit-D is a prerequisite along with exercise and food for muscle growth, contributing via gene transcription to support:

Muscles

  • Production of Myosin Heavy Chain, the motor protein for muscle contraction
  • Production of Insulin-like growth factor receptors, which detect insulin-like growth factor and signal growth

Neuromuscular connection

  • Production of Acetyl-choline receptors, which increases the sensitivity of muscles to stimulation
  • Upregulating Nerve Growth Factor and glial Cell-Derived Neurotrophic factors, supporting muscle nerve junction formation

Immune function

Vit-D helps transcribe genes that support the function of Innate and Adaptive immune responses:

Innate Immunity - antimicrobial role

  • Boost antimicrobial peptides
  • Phagocytosis - help engulfing cells consume microbes and damaged human cells
  • Chemotaxis - guide white blood cells to site of infection

Adaptive Immunity - regulatory role to prevent chronic inflammation and autoimmunity

  • Promote anti-inflammatory cytokines (signalling)
  • Decrease proliferation and differentiation of B-Lymphocytes and Dendritic cells

Blood Vessel Elasticity

Vit-D helps transcribe genes in our blood vessels to help maintain elasticity by:

  • Increasing Matrix Gla Protein - a Ca²⁺ binder that removes calcium deposits in our blood vessels, thus preventing vascular calcification
  • Increasing Endothelial Nitric Oxide Synthase, an enzyme that produces Nitric Oxide (NO) for blood vessel dilation, which is a more elastic vessel structure

References

Scientific articles from where we've produced the material in this page

  1. Bouillon, R., LeBoff, S. M., & Neale, E. R. (2023). Health Effects of Vitamin D Supplementation: Lessons Learned From Randomized Controlled Trials and Mendelian Randomization Studies. Journal of Bone and Mineral Research, 38(1), 1391-1403. https://doi.org/10.1002/jbmr.4888
  2. Janoušek, J., Pilařová, V., Macáková, K., et al. (2022). Vitamin D: sources, physiological role, biokinetics, deficiency, therapeutic use, toxicity, and overview of analytical methods for detection of vitamin D and its metabolites. Critical Reviews in Clinical Laboratory Sciences, 59(1), 517-554. https://doi.org/10.1080/10408363.2022.2070595
  3. Lanham-New, S. A., Webb, A. R., Cashman, K. D., et al. (2020). Vitamin D and SARS-CoV-2 virus/COVID-19 disease. BMJ Nutrition, Prevention & Health, 3(1), 106-110. https://doi.org/10.1136/bmjnph-2020-000089
  4. LeBoff, M. S., Chou, S. H., Ratliff, K. A., et al. (2022). Supplemental Vitamin D and Incident Fractures in Midlife and Older Adults. New England Journal of Medicine, 387(1), 299-309. https://doi.org/10.1056/nejmoa2202106
  5. Rebelos, E., Tentolouris, N., & Jude, E. (2023). The Role of Vitamin D in Health and Disease: A Narrative Review on the Mechanisms Linking Vitamin D with Disease and the Effects of Supplementation. Drugs, 83(1), 665-685. https://doi.org/10.1007/s40265-023-01875-8

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