Dr. Kumar’s Take:
This fascinating historical review charts vitamin D’s evolution from a mysterious cure for rickets to a key hormone regulator impacting everything from bone health to immune function. It reminds us how a nutrient identified through a public health crisis has become central to modern physiology. With widespread subclinical deficiency still common today, we must remember how sunlight and nutrition interplay—and why fortification, sensible sun exposure, and targeted supplementation remain relevant.
Key Takeaways:
✔ Rickets was recognized in the 1600s and surged during the Industrial Revolution due to poor sunlight exposure.
✔ Vitamin D was later identified as both a dietary nutrient and a hormone synthesized through UV light exposure.
✔ Active forms of vitamin D like calcitriol (1,25-(OH)₂D₃) regulate calcium, phosphate, immune health, and gene transcription.
✔ Mutations in vitamin D metabolism pathways can cause rickets, kidney stones, or hypercalcemia.
Actionable tip:
Ensure sufficient vitamin D through a combination of safe sun exposure, diet (e.g., fatty fish, eggs, fortified foods), and supplements—especially in winter or if you have limited sunlight access.
Brief Summary:
This article reviews the 350+ year history of vitamin D research, organized into four distinct eras: the recognition of rickets, the discovery of vitamin D, the identification of vitamin D metabolites, and the understanding of vitamin D’s cellular mechanisms. It shows how vitamin D transformed from a mysterious nutrient deficiency into a powerful hormone with broad effects on human health, including gene regulation and disease prevention.
History of Vitamin D:
This was a narrative historical review published in Endocrine Connections in 2022. It organizes the history of vitamin D research into four chronological eras:
- 1650–1890 – Rickets and sunlight deficiency
- 1890–1930 – Discovery of vitamin D and its chemical structure
- 1930–1975 – Discovery of vitamin D metabolites like 25-OH-D and 1,25-(OH)₂D₃
- 1975–present – Elucidation of vitamin D receptors, binding proteins, metabolic enzymes, and analog drugs
The review highlights major contributors, Nobel prize-winning discoveries, and the eventual development of clinical therapies for vitamin D-related diseases.
Highlights:
- Vitamin D deficiency (rickets) was common in industrial-era Europe due to poor UV exposure.
- Cod liver oil and UV lamps were early treatments before vitamin D was chemically identified.
- Researchers later discovered vitamin D2 (from plants) and D3 (from animals), and their conversion to active metabolites.
- Modern research shows vitamin D functions like a hormone, regulating hundreds of genes via the VDR.
- Genetic defects in vitamin D pathways cause various metabolic bone diseases and hypercalcemia syndromes.
- Today, vitamin D analogs are used clinically for kidney disease, rickets, and even psoriasis.
How Vitamin D Works in the Body
Vitamin D is made in the skin from sunlight or absorbed through food. It’s converted in the liver to 25-OH-D, then in the kidneys to 1,25-(OH)₂D₃ (calcitriol), its active form. This hormone binds to the vitamin D receptor (VDR), acting on the intestines, kidneys, bones, and immune system to manage calcium, phosphate, and more.
Deficiency can result from poor sun exposure, dark skin, certain chronic diseases, or dietary insufficiency. Over time, this leads to weakened bones (rickets or osteomalacia) and potentially immune and metabolic problems.
Related Studies and Research
Global Prevalence of Vitamin D Deficiency: A Meta-Analysis – Provides modern context for historical intake patterns.
Historical Aspects of Vitamin D Research and Public Health Impact – Detailed narrative of vitamin D’s discovery and fortification efforts.
Clinical Overview of Vitamin D Deficiency by Holick et al. – Describes how historical definitions of deficiency evolved.
Analysis of Vitamin D Status in Traditionally Living Maasai and Hadzabe Communities – Compares ancestral vitamin D levels to modern homes.
Comprehensive Review of Vitamin D’s Immunomodulatory Effects in Immune-Related Disorders – Connects historical use to current immune research.
Frequently Asked Questions
What is vitamin D’s main role in the body?
It helps the body absorb calcium and phosphate, supports bone growth and strength, and regulates immune and hormone function.
What are the signs of vitamin D deficiency?
Symptoms include bone pain, muscle weakness, fatigue, and in children, skeletal deformities like bowed legs (rickets).
Can you get enough vitamin D from diet alone?
It’s difficult. While fatty fish, eggs, and fortified foods help, most people also need sunlight or supplements—especially in winter or if they have darker skin.
How is vitamin D measured?
The main blood marker is 25-hydroxyvitamin D (25-OH-D). Optimal levels are usually considered to be 30–50 ng/mL.
Conclusion
This comprehensive historical review offers insight into how vitamin D went from folklore remedy to one of the most studied hormones in medicine. The story spans centuries, pandemics of rickets, Nobel prizes, and molecular breakthroughs. Understanding this arc reminds us why adequate vitamin D—via sunlight, food, or supplementation—remains vital for bone strength, disease prevention, and overall well-being.