However, Lucy Wills was able to demonstrate that the anaemia she observed differed from true pernicious anaemia, as the patients did not have achlorhydria, an inability to produce gastric acid. Furthermore, while patients responded to crude liver extracts, they did not respond to the ‘pure’ liver extracts (vitamin B12) which had been shown to treat true pernicious anaemia. She postulated that there must have been another nutritional factor responsible for this macrocytic anaemia other than vitamin B12 deficiency.