Abstract: Calcium and iron are essential metal elements for human health, as they play important roles in various metabolic processes such as bone formation and oxygen transport. Their interactions may interfere with each other’s absorption and bioavailability; however, deficiencies of calcium and iron are common nutritional problems that may cause osteoporosis and anemia, respectively. Therefore, understanding the mechanism of the intestinal absorption of calcium and iron and their interactions is crucial for developing effective strategies to prevent or treat these nutritional diseases. Many studies have demonstrated that calcium could inhibit iron absorption on a short-term basis, while long-term calcium supplementation has no effect the overall iron homeostasis, perhaps because the effect of calcium intake on iron absorption is a transient and adaptive response. The molecular mechanisms involved may include modulation of iron transporters by calcium, but more research is needed to elucidate this process. Furthermore, there are few studies on how iron affects calcium absorption. High doses of iron may have a negative effect on calcium absorption and retention; however, the specific effect of iron on calcium absorption is not clear. In this article, the current understanding of the intestinal absorption mechanism of calcium and iron, their interactions during the absorption process, and the underlying molecular mechanisms governing their reciprocal effects on each other’s absorption are summarized, which is of guiding significance for formulating efficient strategies for improving calcium and iron intake and absorption as well as for preventing public health problems caused by nutritional deficiencies.

Key words: calcium; iron; absorption; interactions; molecular mechanisms