I have a HIV + friend who has thrush and I want to know what to tell him to buy at the store to eat. What is good to combat getting thrush?

The thrush needs to be treated with an antifungal drug, whether it's a topical one, like a swish & swallow or a special lozenge that dissolves in the mouth, or a pill form. Even after succesful therapy, the thrush can recur if your immune system hasn't improved. I don't know of any foods that will prevent the return of thrush-- the best way to guarantee that is to fix the underlying cause by treating the HIV. During an episode of thrush, many people find it easiest to take liquids or soft foods, but very acdic drinks, like orange juice and coffee, should probably be avoided.