Allergies
Allergies to wheat and dairy are so common, more and more people are realising their food intolerances but there are still a lot of people who don't put 2 & 2 together and realise that every time they eat bread, pastry, etc, they get pains in their stomach and feel lethargic. Or, they eat too much cheese and other dairy products and feel consistently bunged up and their nose is running.