The Discovery of Vitamins: From Beriberi to Vitamin D

Early in the 20th century, nutritional research was blossoming. Scientists realized that the requirements to “support life, growth and reproduction” in both animals and humans were more than simply proteins, carbohydrates, fats, and minerals. Something was missing, and this missing knowledge was key to relieving a host of common afflictions.

Casimir Funk and the idea of “vital amines”

In 1912, Casimir Funk isolated a substance from rice husks that cured beriberi, a disease linked to thiamine (vitamin B1) deficiency. He theorized that other diet-related ailments such as pellagra, scurvy, and rickets could also be due to deficiencies of yet-unidentified compounds. He called them “vital amines” or “vitamines.” The term was later shortened to “vitamins” and became a cornerstone of nutritional science (Funk’s legacy review).

Elmer McCollum and the rickets puzzle

By 1917, Elmer V. McCollum had already helped identify vitamin A. He then studied rickets, a bone-softening disease especially common in northern climates. Rats fed an imbalanced calcium-to-phosphorus diet developed rickets, but cod liver oil reversed it. When vitamin A in the oil was destroyed by oxidation, the oil still cured rickets—suggesting another factor was responsible.

Sunlight, cod liver oil, and vitamin D

Folk remedies had long recommended exposing rachitic children to sunlight. In the 1920s, experiments showed that ultraviolet light exposure cured rickets in both humans and animals. Irradiation of food or even the mineral rations that induced rickets was also protective. Researchers later identified the curative factor as vitamin D2 (ergocalciferol), and by 1931 vitamin D was crystallized and isolated. Today we know that vitamin D3 (cholecalciferol) is synthesized in skin exposed to UVB light (NIH Vitamin D fact sheet).

Vitamin D beyond bone health

Vitamin D is classically known for regulating calcium absorption and bone mineralization. But modern research shows far wider roles:

• Cancer prevention (breast, colon, prostate)
• Cardiovascular health
• Type 1 and type 2 diabetes risk
• Depression and mood regulation
• Immune modulation, including respiratory health

Despite these findings, our understanding of vitamin D’s full physiological role is still evolving. New associations appear in the literature almost daily, yet one hundred years after its discovery, research continues to uncover its influence on chronic disease and healthspan.

From “vital amines” to modern nutrition

The journey from Funk’s “vital amines” to McCollum’s rickets experiments and the crystallization of vitamin D illustrates how recent—yet impactful—the vitamin era truly is. Thanks to pioneers like Funk, McCollum, and many others, the field of nutritional science shifted from macronutrients alone to a recognition of essential micronutrients. Their discoveries continue to shape modern health recommendations, clinical nutrition, and our understanding of diet–disease relationships.

Problem → Deficiency diseases (beriberi, rickets). Solution → Isolated vitamins, cod liver oil, UV light, vitamin D synthesis. Ongoing Mystery → Vitamin D’s broader role in cancer, immunity, mental health, and beyond.