Who invented vitamin D? Unraveling the History of a Crucial Nutrient

January 6, 2026 •

4 min read

The near-eradication of rickets in developed nations is a direct result of the discovery of vitamin D and subsequent food fortification efforts. Yet, the question of who invented vitamin D is not attributable to a single person, but rather a collective scientific effort that unfolded across several decades and countries.

Quick Summary

The discovery of vitamin D was a collaborative scientific effort over decades. Elmer McCollum named the vitamin in 1922, expanding on Edward Mellanby’s work connecting cod liver oil to preventing rickets. Kurt Huldschinsky linked sunlight to its cure, while Harry Steenbock patented the process of irradiating food with ultraviolet light to increase its content.

Key Points

Naming the Vitamin: Elmer McCollum is credited with isolating and naming vitamin D in 1922, distinguishing it from vitamin A.
Identifying the Cause of Rickets: Edward Mellanby first proved in 1919 that rickets was a dietary deficiency disease, curable with cod liver oil.
Connecting Sunlight: Kurt Huldschinsky showed in 1919 that ultraviolet light could effectively treat rickets in children.
Enabling Fortification: Harry Steenbock discovered in the mid-1920s that irradiating foods with UV light increased their vitamin D content.
Unveiling the Structure: German chemist Adolf Windaus won the Nobel Prize in 1928 for elucidating the chemical structure of vitamin D.
A Collaborative Effort: The discovery of vitamin D was not the work of a single inventor but a multi-decade process involving contributions from multiple scientists.

The story of who invented vitamin D is one of intertwined discoveries by multiple researchers. It began not with a single brilliant insight, but with a series of logical steps that built upon earlier findings, revealing the solution to a widespread and debilitating disease known as rickets. While American biochemist Elmer McCollum is officially credited with naming and isolating the substance in 1922, his work was the culmination of critical research by several other pioneering scientists.

The Role of Edward Mellanby and the Dietary Link

For centuries, rickets, a condition causing soft, weakened, and misshapen bones in children, was a major public health issue. Observers had long noted a connection between poor living conditions, limited sunlight, and the disease, but the cause remained a mystery. In 1919, British physician Edward Mellanby designed a critical experiment using dogs to investigate a potential dietary link. He found that he could induce rickets in dogs by feeding them a diet high in oatmeal and low in fat, mimicking the diets common among poor city children. He then demonstrated that adding cod liver oil could reverse the condition. Mellanby concluded that a specific fat-soluble substance in the oil was the anti-rachitic factor. He initially believed it was vitamin A, which had been previously discovered in cod liver oil, but further research proved him wrong.

Elmer McCollum Names the New Vitamin

Elmer McCollum, a prominent American biochemist at Johns Hopkins, had been researching vitamins A and B for years. He was intrigued by Mellanby's findings. In a decisive experiment conducted in 1922, McCollum and his colleagues took Mellanby's lead, but added a crucial step: they bubbled oxygen through the cod liver oil. This process destroyed its vitamin A content but left the anti-rachitic factor intact. When this modified oil was fed to rats with rickets, it still cured the disease. This proved that a distinct substance, separate from vitamin A, was responsible. Following the established alphabetical naming convention for vitamins, McCollum named this new nutrient vitamin D, as it was the fourth vitamin to be identified.

Linking Sunlight and Food Irradiation

Parallel to the dietary research, others were uncovering the link between sunlight and rickets. As early as 1919, German pediatrician Kurt Huldschinsky showed that treating children with artificial ultraviolet (UV) light cured their rickets. The scientific community now understood that two seemingly unrelated factors—a dietary nutrient and UV light exposure—both provided the same benefit. The missing piece was discovered by Harry Steenbock at the University of Wisconsin in the mid-1920s. Steenbock demonstrated that irradiating foods with UV light could increase their vitamin D content. This breakthrough led to the patent for food irradiation and the mass fortification of foods like milk and cereals, making vitamin D widely accessible. Steenbock notably opted not to profit personally from his discovery, instead channeling the royalties through the Wisconsin Alumni Research Foundation (WARF) to support further university research.

Adolf Windaus Clarifies the Structure

While the public health benefits were already being realized, the precise chemical nature of vitamin D remained to be fully understood. This task fell to German chemist Adolf Windaus. For his work in determining the chemical structure of sterols and their connection to vitamins, Windaus was awarded the Nobel Prize in Chemistry in 1928. His research clarified that vitamin D is a type of secosteroid and showed how UV light converts a precursor compound, such as 7-dehydrocholesterol found in the skin, into the active vitamin.

Key Milestones in Vitamin D Discovery

1919 (England): Sir Edward Mellanby proves that a dietary factor in cod liver oil prevents rickets in dogs.
1919 (Germany): Kurt Huldschinsky demonstrates that ultraviolet light can cure rickets in children.
1922 (USA): Elmer McCollum isolates the anti-rachitic factor from cod liver oil, proving it is a distinct nutrient, and names it vitamin D.
1924-1925 (USA): Harry Steenbock discovers that irradiating food with UV light increases its vitamin D content and patents the process.
1928 (Germany): Adolf Windaus is awarded the Nobel Prize in Chemistry for elucidating the chemical structures of vitamin D and related sterols.

Comparison Table: Key Contributors to Vitamin D Discovery


Scientist	Country	Contribution	Year(s)	Impact
Edward Mellanby	Britain	Proved rickets was a dietary deficiency that could be cured by a factor in cod liver oil.	1919	Established the dietary link to rickets prevention.
Kurt Huldschinsky	Germany	Demonstrated that UV light exposure could heal rickets.	1919	Identified a natural, non-dietary method for preventing the disease.
Elmer McCollum	USA	Named and isolated vitamin D as a distinct nutrient from cod liver oil.	1922	Formally identified the vitamin and gave it its name.
Harry Steenbock	USA	Discovered that UV irradiation could increase vitamin D content in foods, leading to fortification.	1924-1925	Pioneered a practical method for mass production of vitamin D.
Adolf Windaus	Germany	Elucidated the chemical structure of vitamin D.	1928	Contributed to the understanding of how the body synthesizes the vitamin via sunlight.

Conclusion: A Legacy of Collaborative Science

The story of who invented vitamin D serves as a powerful reminder that scientific progress is often a collaborative and layered process, with each researcher's finding building upon the work of those who came before them. While Elmer McCollum holds the distinction of naming vitamin D, the victory over rickets was a triumph of shared knowledge. From Mellanby's initial dietary studies to Huldschinsky's linking of sunlight, McCollum's isolation, Steenbock's irradiation, and Windaus's structural clarification, a global effort led to one of public health's most significant achievements. Today, the legacies of these scientists live on in the widespread fortification of our foods and our collective understanding of this crucial nutrient's role in bone health. For more information on the legacy of Elmer McCollum's work, visit the Johns Hopkins Bloomberg School of Public Health website.

Frequently Asked Questions

Vitamin D was discovered, not invented. It is a naturally occurring nutrient that was first identified and named by scientists in the 1920s, after its properties were systematically investigated.

The American biochemist Elmer McCollum named vitamin D in 1922. He gave it the alphabetical designation because it was the fourth vitamin to be identified and named by his research group.

Cod liver oil was famously used to cure rickets in Mellanby's experiments. Elmer McCollum later used it in a key experiment where he destroyed its vitamin A content but found it still cured rickets, proving the existence of a separate, distinct anti-rachitic factor, which he named vitamin D.

In 1919, Kurt Huldschinsky demonstrated that ultraviolet light from the sun could cure rickets. His discovery, along with Mellanby's, showed that both dietary and light-induced factors could prevent the disease, laying the groundwork for further research.

Harry Steenbock, a biochemist at the University of Wisconsin, discovered in the mid-1920s that foods could be irradiated with ultraviolet light to boost their vitamin D content. He patented the process, which allowed for the widespread fortification of milk and cereals.

Adolf Windaus, a German chemist, was awarded the Nobel Prize in 1928 for clarifying the chemical structure of sterols and their connection to vitamins. His work revealed how sunlight converts a precursor in the skin into the active form of vitamin D.

Many different researchers approached the problem of rickets from different angles. This collaborative and competitive scientific environment allowed for the multiple pieces of the puzzle—the dietary factor, the sunlight factor, and the chemical structure—to be discovered in rapid succession in the early 20th century.