Selenium behavior in the soil environment and its implication for human health

ABSTRACT Selenium (Se) is an important element that was discovered in 1817, and since the 1960s, it has been regarded as an essential micronutrient for both animals and humans, playing among other functions a relevant role in the antioxidant system of mammals. Inadequate blood Se levels in the human body is a well-known concern in many parts of the world. This malnutrition problem is often due to Se-poor diet, probably as a result of the low Se availability in soils where crops are growing. Nowadays, it is known that not only the total content, but also the inorganic and organic forms of Se contained in foods are important for human nutrition. However, paradoxically some regions of the world present high Se levels in soils causing several functional disorders and diseases in people who live in seleniferous areas. As essential micronutrient, Se should be supplied in controlled amounts to avoid harmful effects. Therefore, taking into account the importance of the soils as a way to ensure the adequate Se supply for the population, this review has dealt with Se behavior in soil environment (e.g., Se forms and adsorption and desorption reactions) and its relevance for the human health. As a final message, the further understanding of Se behavior in soils to predict its availability for crops in different systems will be a significant approach in future studies to establish forms and safe doses of Se to be added in fertilizers. Agronomic and genetic biofortification of staple crops with Se has been suggested as an important tool to improve Se intake by population in Se-poor sites.

摘要：硒（Selenium, Se）是1817年被发现的重要元素，自20世纪60年代起，其被认定为动物与人类的必需微量营养素，在哺乳动物的抗氧化系统中发挥关键作用。人体血液硒水平不足是全球诸多地区普遍受到关注的健康问题，这类硒缺乏性营养问题通常源于缺硒膳食，而这大概率与作物种植土壤的硒有效性偏低直接相关。如今学界已明确，食品中硒的总含量，以及其无机、有机赋存形态，均对人类营养摄入至关重要。但矛盾的是，全球部分区域的土壤硒含量过高，导致居住在富硒过量区域的人群罹患多种功能紊乱与相关疾病。作为必需微量营养素，硒需通过可控剂量摄入以规避有害健康的影响。鉴于土壤对保障人群充足硒供应的重要意义，本综述聚焦硒在土壤环境中的行为特征（如硒的赋存形态、吸附与解吸反应（adsorption and desorption reactions））及其与人类健康的相关性。本综述的核心启示在于：未来研究中，深入解析硒在土壤中的行为以预测其在不同系统中对作物的生物有效性，将是确立肥料中添加硒的适宜形态与安全剂量的重要研究方向。此外，通过农艺与遗传手段对主粮作物进行硒生物强化，已被提议作为改善缺硒地区人群硒摄入量的重要策略。