For patients who take proton pump inhibitors for a long time and cannot stop taking them, attention should be paid to their effects on nutrient absorption: Effects on calcium absorption: The strong acid-suppressive effect of PPI disrupts the acidic environment of the stomach and upper duodenum, which prevents calcium from ionizing and remaining in the chyme, affecting its absorption. Chronic underabsorption of calcium will cause a decrease in blood calcium concentration and stimulate the release of parathyroid hormone, which in turn promotes bone resorption mediated by osteoclasts, leading to osteoporosis and thus increasing the incidence of fractures. Effect on non-heme iron absorption: Because PPI strongly inhibits gastric acid secretion, trivalent iron is not easily reduced to absorbable divalent iron, which can form more complexes with active vitamin C, sugars and amines, facilitating its absorption in the duodenum. Effect on vitamin B12 absorption: PI inhibits gastric acid secretion and reduces the separation of vegetarian B12 from food protein, which is free and then binds to R protein and internal factor to reach the end of ileum to be absorbed.