> "Furthermore, no specific foodstuff has been incriminated in CD, and combining enteral nutrition with a highly controlled oral diet was recently shown to be effective" ... "It should be noted, however, that enteral nutrition effectively excludes refrigerated foods."
They go on to say that enteral nutrition differ from regular diets so that the mechanism that make them work may not to the fact that they are unrefrigerated.
A refrigeration free diet would not be impossible today, but hard. Given he prevalence of this bacteria today, non-electric cold stores would probably also need to be removed from the supply chain, making even a pre-industrial Western diet problematic.
A sufficiently cooked vegan diet, minus everything that causes problems with people that suffer from Crohn's Disease, maybe would work? Ideally with vegetables that have not been refrigerated. Winter would be pretty bleak.