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Paul Karrer - From Carrots to Vitamins

Did you know that Paul Karrer won the Nobel Prize in Chemistry for his research on the structure of carotenoids, the pigments that give carrots and other vegetables their characteristic colour?

Paul Karrer was born in 1889 in Moscow (Russia) to Swiss parents. The family returned to Switzerland in 1892, and Karrer was educated at the Kantonsschule (high school) in Aargau. He went on to study chemistry at the University of Zurich, where he was mentored by the Nobel Prize winner Alfred Werner. After completing his Ph.D. in 1911, where he primarily focused on inorganic chemistry, he moved to Frankfurt-am-Main (Germany) to shift the direction of his research. While working in the laboratories of Paul Ehrlich, the Nobel Prize laureate considered to be the founder of modern chemotherapy, he developed an interest in biological and medical applications. In 1918, Karrer returned to Zurich and was subsequently appointed Professor of Chemistry as well as Director of the Chemical Institute. He then reoriented the focus of his research towards biologically active natural substances.

Paul Karrer received the Nobel Prize in 1937, shared with the British chemist Norman Haworth, for his investigations on carotenoids, flavins and vitamins A and B2. He passed away in 1971 at the age of 82, after more than 40 years of research career at the University of Zurich.


Paul Karrer conducted extensive research on natural substances, specifically organic compounds that are produced by plants and often have biological activity. He specialised in plant dyes, particularly carotenoids, which give carrots, tomatoes, and certain fruits their distinctive colours.

Paul Karrer accomplished the remarkable feat of isolating vitamin A for the first time in 1931, a discovery that had eluded scientists for many years. He further contributed to the field by determining the structure of vitamin A and demonstrating its origin in the human body.

In addition to his studies on carotenoids, Paul Karrer dedicated part of his research to flavins. Specifically, he investigated riboflavin, also known as vitamin B2, and made notable contributions to the field, such as determining its structure in 1933 and discovering methods for large-scale production.


Paul Karrer's research accomplishments represented significant milestones in basic chemical and biological research, and they also contributed to the development of the prosperous chemical industry in Switzerland.

Switzerland: Paul Karrer Lecture

The Foundation for the Paul Karrer Lecture was established in Zurich in 1959 by CIBA AG, J.R. Geigy, F. Hoffmann-La Roche & Co. AG, Sandoz AG, Société des Produits Nestlé AG and Dr. A. Wander AG, to honour Paul Karrer's contributions to the development of chemistry on the occasion of his 70th birthday and retirement. The foundation's purpose is to invite an outstanding researcher in the field of chemistry to present a scientific lecture at the University of Zurich. The medal depicts a relief of Paul Karrer's profile on the front, while the back is engraved with the words " Universität Zürich – Paul Karrer Vorlesung”.


1) J. S, Siegel. 50 Years of the Paul Karrer Gold Medal: 1959–2009. Chimia 2009, 63, 545.

2) University of Zurich - Paul Karrer Nobel Prize in Chemistry 1937. The Nature of Vitamins: from Karrer’s colourful carrots…to Nevado’s marine organisms.

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