Final answer:
Peptic ulcers are most commonly caused by Helicobacter pylori infection and the chronic use of non-steroidal anti-inflammatory drugs. Diet does not have a significant impact on the development of peptic ulcers.
Step-by-step explanation:
Peptic ulcers are most commonly caused by infection with the bacterium Helicobacter pylori or the chronic use of non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin or ibuprofen. Other factors such as tobacco smoking and stress may contribute to the development of peptic ulcers, although their role is not yet fully understood. Contrary to popular belief, diet does not appear to play a significant role in causing or preventing peptic ulcers.