A hiatal hernia makes it easier for stomach acids to rise to the esophagus, usually called heartburn. 
To reduce this symptom It's important a diet that consists of
 less: citrus, spicy, fried, fatty foods, coffee, tea, chocolate, 
carbonated drinks, dairy products and tomato (because it's also acidic).
Some examples of appropriate foods are: apples, bananas, grains, soy milk, water, carrots, potatoes, peas, a low fat yogurt/cheese, (anything with low fat is ideal), etc.