What gastrointestinal change is associated with normal aging?

Decreased production of gastric acid is a well-documented physiological change that occurs with normal aging. As individuals age, the parietal cells in the stomach tend to produce less gastric acid, which can lead to various gastrointestinal issues such as decreased digestion efficiency and altered absorption of certain nutrients, particularly vitamin B12, calcium, and iron. This decrease can be attributed to changes in the gastrointestinal tract, including diminished gastric motility and changes in hormonal regulation.

The other options reflect changes that are either less common or not typically associated with the normal aging process. For example, the incidence of gallstones tends to increase with age due to factors such as increased cholesterol in bile and changes in gallbladder motility. Salivation often decreases with age, leading to dry mouth (xerostomia), rather than increasing. Lastly, esophageal emptying usually slows down with age, which can contribute to dysphagia or difficulty swallowing, rather than increasing as suggested.