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, calcium and iron deficiencies are common nutritional problems that may cause osteoporosis and anemia, respectively. Therefore, understanding the mechanisms of calcium and iron absorption in the intestine and their interactions is crucial for developing effective strategies to prevent or treat these conditions. Many studies have demonstrated that calcium could inhibit iron absorption on a short-term basis, while long-term studies suggest that calcium supplementation do not affect the overall iron status. This may indicate a transient and adaptive response to calcium intake. The molecular mechanisms involved may include modulation of iron transporters by calcium, but more research is needed to elucidate this process. Furthermore, there are fewer 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, and no comprehensive reviews have been reported on this topic. In this review, the current understanding of the absorption of calcium and iron in the gut, their interaction during the absorption process, and the underlying molecular mechanisms governing their reciprocal effects on absorption are summarized. Above information are valuable in formulating efficient strategies for improving calcium and iron intake and absorption, as well as preventing nutritional deficiencies that have an impact on public health.

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