There is a good reason why the standard 'lifeboat cracker' and survival biscuits intended for fallout shelters were essentially simple vitamin fortified flour/water cracker. They are bland, almost tasteless, and are highly unlikely to be offensive or interfere with digestion. Being so bland is something of a selling point because it makes it less likely that people will raid the survival foods for a snack.

It pays to keep some clearly unobjectionable and easily digestible foods on hand. Some of this has to do with cultural differences but it also can be an issue with medical conditions. I had a friend who was getting radiation and chemotherapy and the only food she could keep down were water crackers. We kept her hydrated with Gatoraide cut with water, and very weak tea.

When I was fighting my way through a case of food poisoning plain crackers got me through the worse of it. Even then I had difficulty keeping them down and had to force myself to eat. When I recovered a bit I expanded my repertoire to Graham crackers and bits of banana.