The Collaborative Story of Who Discovered Vitamin D and When

January 6, 2026 •

4 min read

For centuries, the debilitating bone disease rickets plagued children worldwide, but it wasn't until the early 20th century that the cause was definitively identified. A complex series of investigations eventually revealed who discovered vitamin D and when, showcasing a multi-researcher effort rather than a single 'eureka' moment.

Quick Summary

The discovery of vitamin D was a collaborative effort involving several scientists in the early 1920s, most notably American biochemist Elmer McCollum, who isolated and named the nutrient, building on the foundational work of British and German researchers. McCollum's research proved a specific nutrient cured rickets.

Key Points

Initial Link: Sir Edward Mellanby first demonstrated in 1918 that a fat-soluble factor in cod liver oil could cure rickets in dogs.
Sunlight Connection: German physician Kurt Huldschinsky showed in 1919 that ultraviolet light exposure could also cure rickets in children.
Official Naming: American biochemist Elmer McCollum isolated the anti-rachitic factor from cod liver oil in 1922 and officially named it vitamin D.
Food Fortification: Harry Steenbock discovered in the mid-1920s that irradiating foods with UV light increased their vitamin D content, leading to milk fortification programs.
Chemical Structure: The chemical structure of vitamin D2 and D3 was later elucidated in the 1930s by teams led by Adolf Windaus and others.
A Combined Effort: The discovery is attributed to a combination of research efforts rather than a single individual, spanning from the 1910s to the 1930s.

The Era of Rickets: A Pervasive Health Crisis

Before the discovery of vitamin D, rickets was a widespread and devastating disease, particularly in the polluted industrial cities of 17th-century Europe and later in the United States. This condition, which causes the bones to become soft and malformed, was first scientifically described in the mid-1600s, but its cause remained a mystery for centuries. The disease was so prevalent that it was sometimes called the 'English disease'. By the late 1800s, it was well-known that cod liver oil could be used as a treatment, and some recognized the link between sunlight and the disease, but the underlying scientific reason was unknown. The stage was set for a series of discoveries that would change public health forever.

The Pioneering Roles of Mellanby and Huldschinsky

The discovery of vitamin D did not happen in a single stroke but unfolded in stages, with multiple researchers contributing key puzzle pieces. Sir Edward Mellanby, a British biochemist, played a crucial early role.

Sir Edward Mellanby's 1918 breakthrough: Mellanby conducted groundbreaking experiments with dogs, feeding them a diet that induced rickets. He then found that adding cod liver oil to their diet effectively cured the disease. He concluded that a fat-soluble substance was the missing dietary factor, believing it was likely the same as vitamin A. His work established that rickets was a deficiency disease.
Kurt Huldschinsky's 1919 finding: Around the same time, German researcher Kurt Huldschinsky demonstrated that exposure to ultraviolet light could cure rickets in children. This highlighted the role of sunlight and a substance produced in the skin in preventing the disease, establishing a parallel cure to cod liver oil.

Elmer McCollum Names and Isolates the Nutrient

The crucial differentiating step came in 1922 from American biochemist Elmer McCollum at Johns Hopkins University. He had already discovered Vitamin A in 1913, but his research into rickets revealed a new factor.

The key experiment: McCollum heated cod liver oil to destroy its vitamin A content. He discovered that the oil, despite lacking vitamin A, was still effective at curing rickets in his animal subjects.
The naming of vitamin D: Concluding that this was a distinct nutrient, McCollum named it 'vitamin D,' as it was the fourth vitamin to be discovered. His team, with collaborator Nina Simmonds, contributed significant groundwork to the understanding of this vital nutrient.

Steenbock and Windaus Advance the Field

Following McCollum's naming, other scientists rapidly built on the foundation laid. Harry Steenbock at the University of Wisconsin discovered that irradiating food with ultraviolet light could increase its vitamin D content. In 1924, Steenbock patented this process and, instead of profiting personally, used the licensing fees to establish the Wisconsin Alumni Research Foundation (WARF) to support future research. Meanwhile, in the 1930s, European chemists, including Adolf Windaus (a Nobel laureate), chemically identified and synthesized the specific forms of vitamin D, ergocalciferol (D2) and cholecalciferol (D3).

The Aftermath: Fortification and Public Health

The culmination of these discoveries had a profound impact on public health. The ability to fortify foods like milk and cereal with vitamin D led to the near-eradication of rickets in developed countries by the mid-20th century. This demonstrated the power of nutritional science to solve large-scale health problems. The legacy of these pioneers continues today, as research delves deeper into the role of vitamin D as a hormone involved in many biological functions beyond just bone health.

The Historical Contributions of Key Vitamin D Researchers


Researcher/Group	Nationality	Year(s)	Key Contribution
Sir Edward Mellanby	British	1918	First demonstrated rickets is a dietary deficiency disease, identifying a fat-soluble substance (in cod liver oil) as the cure.
Kurt Huldschinsky	German	1919	Showed that ultraviolet light could cure rickets, highlighting the role of sunlight.
Elmer McCollum	American	1922	Isolated and named the anti-rachitic factor in cod liver oil, calling it vitamin D.
Harry Steenbock	American	Mid-1920s	Discovered that irradiating foods with UV light increased their vitamin D content, leading to fortification.
Adolf Windaus et al.	German	1930s	Isolated and determined the chemical structure of vitamins D2 and D3.

Conclusion: A Collaborative Victory for Science

The question of who discovered vitamin D and when is best answered by recognizing the collaborative and iterative nature of scientific progress. No single individual can claim exclusive credit. Instead, a series of pivotal findings—from Mellanby's dietary link in 1918 to McCollum's naming in 1922, and Steenbock and Windaus's subsequent work—came together to illuminate the mystery of rickets. This shared history is a testament to how multiple lines of inquiry converge to create lasting change in human health. The legacy of these discoveries is seen in fortified foods and widespread supplements that continue to benefit populations around the globe today.

For more detailed information, the National Institutes of Health provides a comprehensive history of the discovery and production of vitamin D.

Frequently Asked Questions

No, the discovery of vitamin D was a collaborative process involving several researchers whose findings built upon one another between 1918 and the 1930s.

Vitamin D was officially named in 1922 by American biochemist Elmer McCollum, who isolated it from cod liver oil.

Vitamin D3 (cholecalciferol) is the form produced by animals, including humans, when exposed to sunlight, while Vitamin D2 (ergocalciferol) comes from plant and fungal sources. They were chemically characterized in the 1930s.

In 1919, German researcher Kurt Huldschinsky demonstrated that ultraviolet light exposure could cure rickets in children.

Harry Steenbock discovered that irradiating foods with ultraviolet light could increase their vitamin D content, paving the way for food fortification to fight rickets.

British biochemist Edward Mellanby demonstrated in 1918 that rickets was a dietary deficiency disease and that a fat-soluble factor (later identified as vitamin D) found in cod liver oil could prevent it.

Following Harry Steenbock's patented process in the 1920s for irradiating foods, programs were launched to fortify common items like milk and cereal, which significantly reduced the incidence of rickets.