Abstract Vitamin C was the first vitamin to be manufactured by chemical synthesis on an industrial scale, and today more vitamin C is produced than any other vitamin. The bulk of manufacture now takes place in China. Reichstein and Grüssner's efficient second synthesis developed in 1934 was the prominent industrial synthesis until the 2000s, but has been entirely replaced by a 2‐step fermentation process from sorbitol to 2‐ketogulonic aced (2‐KGA), with the following chemical conversion of 2‐KGA to ascorbic acid as in the Reichstein process. Alternative fermentation routes using microalgae or yeast have been reported, but not commercialized. Both epidemiological and biochemical studies indicate that vitamin C may play an important role in the prevention of cancer, cataracts, and other disorders. However, there are still many gaps in the knowledge of vitamin C, eg, in its role in nutritional interrelationships and in metabolic interactions, as well as its role in prevention of various diseases in humans.