chapter 01
What is β-carotene?
The Battle Against Vitamin A Deficiency
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β-carotene is one of more than 600 carotenoids known to exist in nature. About 50 of the naturally occurring carotenoids can potentially yield vitamin A; they are thus referred to as provitamin Acarotenoids. The term ‘provitamin’ denotes a substance which is converted into a vitamin within an organism. β-carotene is the most abundant and most efficient carotenoid in our foods. It has antioxidant properties that help neutralize free radicals – reactive and highly energized molecules which are formed either through certain normal biochemical reactions in the body (e.g., the immune response), or else through external sources such as air pollution or cigarette smoke. Free radicals can damage lipids in cell membranes as well as the genetic material in cells, and the resulting damage may lead to the development of cancer. β-carotene is the main dietary source of vitamin A. The best sources of β-carotene are yellow/orange vegetables and fruit and dark green leafy vegetables. The β-carotene content of fruit and vegetables varies according to the season and degree of ripening.
Otto Isler, a biochemist who worked for Hoffmann-La Roche, was the first person to synthesize vitamin A. Before 1945, the synthesis of vitamin A was not considered technically feasible, despite the fact that the chemical structure of vitamin A had been known since 1931. Otto Isler, however, who had a profound interest in the chemistry of natural compounds, undertook on his own initiative to try to find a way of synthesizing the vitamin.
Otto Isler
Passionate in his search, Isler managed to convince his superiors within the company to fund major research into a potential synthetic route for producing vitamin A. Supported by a powerful team, he created a process whose main step is the Grignard reaction – an organometallic chemical reaction discovered by the French chemist François Auguste Victor Grignard, who was awarded the 1912 Nobel Prize for Chemistry in recognition of this achievement. The chemical process created by Isler and his team is still in use today at the manufacturing plant in Sisseln near Basel, Switzerland. The Sisseln plant formed part of Roche’s Vitamins & Fine Chemicals Division, which was acquired by the Netherlands-based life sciences and materials sciences company Royal DSM N.V. in 2003.
Victor Grignard
First piloted in 1947, Isler’s vitamin A manufacturing process was so successful that regular production commenced in 1948 with a targeted yield of 10 kg per month. Only a few months later, however, this target had to be revised upwards to 50 kg per month, and demand for synthetic vitamin A only increased thereafter. Isler and his team became responsible for continuously optimizing their pioneering process. A decade and a half after pioneering the industrial manufacture of vitamin C, the chemists of Hoffmann-La Roche were leading the world again. Vitamin A, which they succeeded in synthesizing against all expectation, was to have a transformational effect on the lives of countless people around the world. But for this to happen, the humanitarian initiative Sight and Life had to be called into existence.