Audrey Josephine Cahn (17 October 1905 – 1 April 2008) was an Australian microbiologist and nutritionist.
The daughter of Professor William Alexander Osborne and Ethel Elizabeth Goodson, a medical practitioner and industrial hygienist, she was born Audrey Josephine Osborne in Melbourne and grew up on the campus of the University of Melbourne. She earned a Bachelor of Agricultural Science at the University in 1929 and, later, received a diploma in dietetics. She first worked as a microbiologist and food analyst for Kraft. In 1930, she married Leslie Cahn, an architect. She was employed as chief dietician at St Vincent's Hospital, at the Victorian Mental Hygiene Department and at the Royal Perth Hospital. During World War II, she was chief dietician at the Heidelberg Military Hospital. From 1947 to 1959, she was a dietetics lecturer at the University of Melbourne; from 1959 until 1968, when she retired, she was chief lecturer in nutrition and applied dietetics at the University.
She was a founding member of the Dietetics Association. Cahn was among the first experts to recommend reducing fat intake and substituting polyunsaturated fatty acids for saturated fats. She helped conduct a longitudinal study of child growth in Melbourne (1954–1971) which allowed the growth patterns of Australian children to be compared with children in Britain and the United States.
Cahn died in Canberra at the age of 102.
Audrey Cahn Street in the Canberra suburb of Macgregor was named in her honour.