Vitamin | Definition, Types, & Facts

Discovery and original designation

Some of the first evidence for the existence of vitamins emerged in the late 19th century with the work of Dutch physician and pathologist Christiaan Eijkman. In 1890 a nerve disease (polyneuritis) broke out among his laboratory chickens. He noticed that the disease was similar to the polyneuritis associated with the nutritional disorder beriberi. In 1897 he demonstrated that polyneuritis was caused by feeding the chickens a diet of polished white rice but that it disappeared when the animals were fed unpolished rice. In 1906–07 British biochemist Sir Frederick Gowland Hopkins observed that animals cannot synthesize certain amino acids and concluded that macronutrients and salts could not by themselves support growth.

In 1912—the same year that Hopkins published his findings about the missing nutrients, which he described as “accessory” factors or substances—a Polish scientist, Casimir Funk, demonstrated that polyneuritis produced in pigeons fed on polished rice could be cured by supplementing the birds’ diet with a concentrate made from rice bran, a component of the outer husk that was removed from rice during polishing. Funk proposed that the polyneuritis arose because of a lack in the birds’ diet of a vital factor (now known to be thiamin) that could be found in rice bran. Funk believed that some human diseases, particularly beriberi, scurvy, and pellagra, also were caused by deficiencies of factors of the same chemical type. Because each of these factors had a nitrogen-containing component known as an amine, he called the compounds “vital amines,” a term that he later shortened to “vitamines.” The final e was dropped later when it was discovered that not all of the vitamins contain nitrogen and, therefore, not all are amines.

In 1913 American researcher Elmer McCollum divided vitamins into two groups: “fat-soluble A” and “water-soluble B.” As claims for the discovery of other vitamins multiplied, researchers called the new substances C, D, and so on. Later it was realized that the water-soluble growth factor, vitamin B, was not a single entity but at least two—only one of which prevented polyneuritis in pigeons. The factor required by pigeons was called vitamin B1, and the other factor, essential for rats, was designated vitamin B2. As chemical structures of the vitamins became known, they were also given chemical names, e.g., thiamin for vitamin B1 and riboflavin for vitamin B2.