Hiatus hernia occurs when part of the stomach has passed through the hole (the hiatus) in the diaphragm which allows the oesaphagus to pass from the chest through to the stomach. It is usually the top of the stomach that slides through giving rise to heartburn and reflux.
All the advice given for digestion and heartburn are appropriate for this condition.
Most cases are a direct result of obesity, so maintaining your correct body weight can help prevent it. Lose weight if you are overweight.
Raising the head of your bed using bricks or blocks can help prevent the contents of the stomach going back up the oesaphagus.