Early in the 20th century, research in the nutritional arena was blossoming. Scientists were swiftly realizing that the nutritional requirements to "support life, growth and reproduction" in both animals and humans were more than simply proteins, carbohydrates, fats and minerals, as commonly believed. And, all scientists working in the field knew that this missing knowledge was key to relieving a host of common afflictions.
In 1912 one scientist, Casimir Funk, isolated a substance found in the hulls of rice that cured beriberi, a nutritional disease linked to thiamine (B1) deficiency. From this revelation, he theorized that other diet-related ailments such as pellagra, scurvy and rickets could also be a consequence of deficiencies of yet unidentified substances. He further hypothesized that these substances would have the same basic property of a protein, and called them "vital amines" or "vitamines" Later this term was embraced (with the ‘e’ omitted) and became a major focus of nutritional research for the next 30 years, yielding discovery after discovery of essential nutrients.
In 1917, building on previous research, Elmer V. McCollum began experiments with rats fed modified diets resulting in another diet-related health condition, rickets. This malady was prevalent in Europe, particularly in Scotland , and the northern US. McCollum fed rats a diet with an imbalanced ratio of calcium to phosphorus, a mixture which created rickets. He knew that Cod liver oil had been shown to prevent rickets. Having already isolated vitamin A in cod liver oil, McCollum speculated this nutrient was the factor responsible for reversing rickets. However, he found that after using oxygen to destroy the vitamin A in the cod liver oil, it still retained the ability to cure rickets. This meant that another factor was responsible for the curative effect.
Exposing an infant to sunlight was a traditional folk remedy in Europe for the treatment of rickets. Experiments using ultraviolet (UV) lamp exposure to rachitic patients were also known to be effective. A breakthrough occurred when it was found that not only was the irradiation of the rachitic rats curative, but irradiation of the imbalanced mineral rations that caused rickets was also curative. This contradiction led to many researchers trying to isolate the factor triggered by the UV waves. Little did they know that the process was generating vitamin D2 (ergocalciferol). Rapid progress led to separation of a lipid, then to a sterol fraction and finally in 1931 vitamin D was crystallized.
Today we know that vitamin D3 (cholecalciferol) is synthesized in our skin through exposure to sunlight. We also know that vitamin D has a complex regulatory effect upon calcium in our bodies and in the mineralization of our bones. But that’s only skimming the surface of this vitamin’s function. Further exploration has generated knowledge of the effects of vitamin D on many disease processes including breast, colon and prostate cancer, heart disease, both type 1 and type 2 diabetes, and depression, to name a few.
The winding road in the identification of vitamin D, as well as each individual vitamin, is a comparatively recent phenomenon in nutritional history. Yet one hundred years later, our understanding of vitamin D’s wider role is still embryonic. New associations to health are in the news almost daily. But thanks to pioneers like Casimir Funk, E.V. McCollum and many others, nutritional research and its importance to overall health continues to evolve.