Keeping kosher is one of the oldest known diets across the world and, for an observant Jew, maintaining these dietary laws (known as Kashruth) is a fundamental part of everyday life. It is a key part of what identifies them as Jews, both amongst their own communities and to the outside world.

Oxford's Jewish quarter was established around St. Aldates in the twelfth and thirteenth centuries, following William the Conqueror's invitation to Jews in Northern France to settle in England. Recent excavations by Oxford Archaeology at St Aldates, in the historic heart of Oxford, revealed evidence for two houses, which a medieval census suggested belonged to two Jewish families. One was owned by Jacob f. mag. Moses and called Jacob's Hall, and was said to be one of the most substantial private houses in Oxford and the other house was owned by an Elekin f. Bassina.

During excavations, archaeologists found a stone-built structure, identified as a latrine, and dated to the late 11th and 12th century. A remarkable animal bone assemblage was unearthed in this latrine, dominated by domestic fowl (mainly goose), and with a complete absence of pig bones, hinting at a kosher diet. Fish bones comprised only species such as herring which are kosher. This combination of species suggests a Jewish dietary signature, identified in British zooarchaeology for the first time, and just the third time in medieval Europe.

To investigate whether the inhabitants of the two houses were eating a Jewish diet, the team used a combined chemical and isotopic approach to identify and quantify the food residues absorbed into medieval vessels found at the site.