Eat non-acidic foods
A person with heartburn
should avoid vinegar and other acidic foods or liquids.
Sodas (carbonated drinks), orange juice, and many other juices are acidic. The person is likely already taking acid blockers and antacids to decrease acidity in the stomach. It would be bad to eat or drink more acid, because the whole point of treatment is to decrease acid in the stomach and esophagus.