“…She identified linoleic and linolenic acids as the essential dietary fatty acids, and showed that these could be converted in vivo into the more complex 20 C polyunsaturated fatty acid, arachidonic acid, the precursor of the prostaglandins [10][11][12] . Finally, in 1940, just when the Lister was being evacuated from London to Cambridge to avoid bombing, she published the correct full structure for arachidonic acid including the positions of the double bonds 13 . This work was recently celebrated in a review in the Journal of Lipid Research 14 which highlighted the small quantities of material that Ida and her collaborators had to work with and the use of entirely traditional techniques, with no modern spectroscopy.…”