What nutrient's absorption might be impaired due to decreased stomach acid among the elderly?

The absorption of iron can be significantly impaired in individuals with decreased stomach acid, which is often a concern among the elderly. Stomach acid, primarily hydrochloric acid, plays a crucial role in the digestion and absorption of nutrients. Iron absorption is especially influenced by the acidity in the stomach, as a lower pH enhances the solubility of iron, converting it from ferric iron (non-heme, less absorbable) to ferrous iron (more absorbable).

In the elderly population, the production of stomach acid may decline due to factors such as age-related changes in gastric physiology or the use of medications that suppress acid production. This reduced acidity can lead to decreased conversion and absorption of iron, resulting in a higher risk for iron deficiency anemia.

While calcium and vitamin D are also important for elderly individuals, their absorption is less directly affected by stomach acid compared to iron. Riboflavin absorption does not have a significant association with stomach acidity, making iron the nutrient most affected by decreased stomach acid levels in this context.