Zinc is a vital trace element essential for numerous physiological processes in the human body, including enzyme function, gene expression regulation, DNA metabolism, cell differentiation, signal transduction, immune response, and apoptosis. However, an excess of zinc can lead to harmful effects, such as anemia, neutropenia, and zinc-induced copper deficiency. The World Health Organization (WHO) recommends a dietary reference value of 6.7 to 15 mg per day, while the European Food Safety Authority (EFSA) and the Food and Drug Administration (FDA) set the tolerable upper intake levels (UL) at 25 mg and 40 mg per day, respectively. This review discusses the current knowledge on zinc bioavailability and toxicity, focusing on acute and chronic exposure. It highlights the importance of maintaining zinc homeostasis through dietary intake and absorption mechanisms, such as the SLC39/ZIP and SLC30/ZnT protein families. The review also addresses the risk factors for zinc inadequacy, including pregnancy, lactation, vegetarianism, and veganism, and the potential health consequences of zinc toxicity, such as gastrointestinal, neurological, cardiorenal, and immunological effects. Additionally, the review explores the diseases associated with zinc toxicity, including zinc-induced copper deficiency, neuronal death, and various neurological and cancer conditions. It emphasizes the importance of balancing zinc intake to avoid both deficiency and toxicity, and provides guidelines for preventing and diagnosing zinc toxicity. The review concludes by discussing the role of zinc in maintaining overall health and the need for further research to optimize zinc intake and management.Zinc is a vital trace element essential for numerous physiological processes in the human body, including enzyme function, gene expression regulation, DNA metabolism, cell differentiation, signal transduction, immune response, and apoptosis. However, an excess of zinc can lead to harmful effects, such as anemia, neutropenia, and zinc-induced copper deficiency. The World Health Organization (WHO) recommends a dietary reference value of 6.7 to 15 mg per day, while the European Food Safety Authority (EFSA) and the Food and Drug Administration (FDA) set the tolerable upper intake levels (UL) at 25 mg and 40 mg per day, respectively. This review discusses the current knowledge on zinc bioavailability and toxicity, focusing on acute and chronic exposure. It highlights the importance of maintaining zinc homeostasis through dietary intake and absorption mechanisms, such as the SLC39/ZIP and SLC30/ZnT protein families. The review also addresses the risk factors for zinc inadequacy, including pregnancy, lactation, vegetarianism, and veganism, and the potential health consequences of zinc toxicity, such as gastrointestinal, neurological, cardiorenal, and immunological effects. Additionally, the review explores the diseases associated with zinc toxicity, including zinc-induced copper deficiency, neuronal death, and various neurological and cancer conditions. It emphasizes the importance of balancing zinc intake to avoid both deficiency and toxicity, and provides guidelines for preventing and diagnosing zinc toxicity. The review concludes by discussing the role of zinc in maintaining overall health and the need for further research to optimize zinc intake and management.