Which of the following factors contributes to the formation of peptic ulcers?

The formation of peptic ulcers is significantly influenced by Helicobacter pylori infection. This gram-negative bacterium resides in the stomach lining, where it can cause inflammation and damage to the gastric mucosa. The presence of H. pylori disrupts the normal protective mechanisms of the stomach, leading to increased acidity and the potential development of ulcers. It is estimated that a substantial percentage of peptic ulcers are associated with this infection, highlighting its critical role in ulcer formation.

Other factors, while they may contribute variously to gastrointestinal health, do not have the same direct link to ulcer development. For example, spicy foods may irritate an existing ulcer but are not recognized as a primary cause. Similarly, decreased gastrin production and increased bicarbonate retention do not directly lead to ulcer formation in the same significant manner as H. pylori infection. Thus, the association of Helicobacter pylori with peptic ulcer disease is well-established, making it the correct answer.