Paul Karrer
Nobel Prize in Chemistry 1937

The Nature of Vitamins

Paul Karrer unraveled the chemical structure of plant dyes and vitamins, and showed how beta carotene is used by the body to produce vitamin A.

Zurich was Paul Karrer’s stomping ground. After studying at the Department of Chemistry at the University of Zurich under Nobel laureate Alfred Werner, he then taught and researched for 40 years at the same institution. Colorful flowers occupied a prominent place in Karrer’s laboratory. Plant dyes had interested Karrer from an early stage, and he worked on them throughout his career. He achieved particular success with the carotenoids – chemical compounds that give fruit and vegetables such as carrots, tomatoes, saffron, and bell peppers, their colors of yellow, orange, or red.

Karrer was able to use chemical analysis to establish the structure and composition of many such carotenoid compounds. Moreover, he identified a link to the vitamins essential to the human body. In the early 1930s, he was able to demonstrate that vitamin A, partially responsible for physical growth and also for the development of rhodopsin in the eye, was generated by the body from the red carrot pigment, beta carotene, by splitting the molecule. He was also the first scientist to determine the structure of this important vitamin. It was in part for these achievements that Karrer was awarded the Nobel Prize in Chemistry in 1937.

Paul Karrer had an astonishing sense for research topics that were both scientifically important and commercially interesting, as shown by the 78 patents he registered during his career. His research findings are not only milestones in basic chemical and biological research; they also helped lay the foundations for the success of the chemical industry in Switzerland.