Why Vitamin A Was Named "Vitamin A"
Vitamin A received its name because it was the first fat-soluble "accessory factor" discovered that was essential for life, initially termed "fat-soluble A" in 1918 before being renamed "vitamin A" in 1920. 1, 2, 3
Historical Context of Vitamin Discovery
The naming of vitamin A emerged from a century-long scientific journey that fundamentally challenged prevailing nutritional dogma:
In the early 1900s, scientific consensus held that only four nutritional factors were essential: proteins, carbohydrates, fats, and minerals—vitamins were completely unknown. 4
Between 1911-1913, multiple researchers independently demonstrated that certain "accessory food substances" in astonishingly small amounts were vital for survival, contradicting the belief that all fats had equivalent nutritional value. 2, 3
In 1911, Casimir Funk isolated a concentrate from rice polishings that cured polyneuritis in pigeons and coined the term "vitamine" (from "vita" meaning life and "amine" referring to nitrogenous compounds), believing these substances were amines. 3, 5
The scientific community formally accepted the term "vitamins" in 1912, though the final "e" was later dropped when researchers realized not all these substances were amines. 3, 5
The Specific Discovery of Vitamin A
The compound that would become vitamin A was identified through parallel research efforts:
In 1913, two independent research teams—Elmer McCollum and Marguerite Davis at Wisconsin, and Thomas Osborne and Lafayette Mendel at Yale—demonstrated that butter and egg yolk contained a growth-supporting factor absent in lard and olive oil. 2, 3
This fat-soluble "accessory factor" was initially designated "fat-soluble A" in 1918 to distinguish it from water-soluble factors. 2, 3
The designation was simplified to "vitamin A" in 1920, establishing the alphabetical naming convention that would be applied to subsequently discovered vitamins. 2
Paul Karrer elucidated vitamin A's chemical structure in 1932, Harry Holmes and Ruth Corbet isolated and crystallized it in 1937, and synthetic production methods were developed by 1947. 2
Why the Letter "A" Specifically
Vitamin A earned the first letter of the alphabet simply because it was the first fat-soluble vitamin to be characterized and distinguished from water-soluble factors. 1, 2, 3
When a second fat-soluble factor effective against rickets (rather than xerophthalmia) was identified, it logically received the next letter designation: vitamin D. 3
This alphabetical system became the standard nomenclature framework, with vitamin C (ascorbic acid) named for the water-soluble factor preventing scurvy that was isolated in 1928. 3
Clinical Relevance Today
Understanding vitamin A's historical discovery context remains clinically important:
Vitamin A functions as a prohormone with active metabolites (all-trans and 9-cis retinoic acid) that regulate gene expression in over 500 target genes through nuclear receptor binding. 1
The vitamin's critical roles in vision, reproduction, cellular growth, differentiation, and immune function were progressively elucidated throughout the 20th century, extending well into the 1990s for immunity and child survival research. 2
Modern clinical practice must balance deficiency prevention (xerophthalmia, night blindness) against toxicity risks, particularly in chronic kidney disease where impaired renal catabolism of retinol-binding protein causes accumulation despite potential tissue depletion. 6, 7