Vitamin B12 molecular structure, c 1957-1958.
© Science Museum / Science & Society Picture Library
Ball and spoke model of Vitamin B12 (cyanocobalamine) made for Sir Alexander Todd's research group at Cambridge University and displayed at the Brusels Universal Exhibition ('Expo') in 1958. Todd worked on the chemical structure of Vitamin B12 and this model is a result of his group's work. The full structure of this complex and large vitamin was determined by Dorothy Crowfoot Hodgkin using X-ray crystallography in 1957 before Todd was able to work it out using chemical means. B12 is produced by micro-organisms in the gut; the richest natural source is raw liver. Deficiency leads to pernicious anaemia, the poor development of red blood cells, resulting in posible degeneration of the spinal chord. Sufferers develop extensive bruising and recover slowly from even minor injuries.