Which of the following can affect the absorption of B12?

Pantoprazole can affect the absorption of Vitamin B12 due to its mechanism of action as a proton pump inhibitor (PPI). The primary role of pantoprazole is to reduce stomach acid production, which can lead to decreased acidity in the gastrointestinal tract. Vitamin B12 absorption is dependent on adequate gastric acidity because the vitamin is bound to protein in food and requires the presence of intrinsic factor, a glycoprotein released by the stomach lining that binds to B12 in the presence of sufficient acid. When stomach acid is reduced, intrinsic factor may not function optimally, resulting in decreased absorption of B12 from the diet. This could lead to deficiencies, especially in individuals taking pantoprazole over prolonged periods.

In contrast, a low-fat diet, increased hydration, and regular exercise do not have a direct impact on the absorption of Vitamin B12. While a balanced diet is essential for overall health, and hydration can promote better digestive health, these factors do not specifically influence the mechanisms involved in B12 absorption to the same extent as the acidity changes caused by medications like pantoprazole. Therefore, pantoprazole is identified as the factor that can notably impact B12 absorption.