我国典型长寿区域高龄老人硒营养的环境调控机理

Applied fundamental research aimed at improving health and longevity of the elderly population is not only an urgent need for the Chinese government but also a major national strategy demand for the people’ livelihood and well-being. Selenium has been shown to play an important role in preventing age-related diseases, improving health and other aspects of aging. Based on the overall low dietary selenium intakes and the selenium nutrition loss of the oldest-old, an integrated study is therefore proposed in this project to carry out the environmental regulation mechanism of selenium nutrition of the oldest-old in typical longevity region(s) in China. Through a integrated use of rhizobox cultivation test, digestion simulation of the oldest-old, experimental animal models as well as 3S technologies (namely, Remote Sensing, Geographic Information Systems and Global Positioning System) and numerical models, we try to explore the feasible paths to improve the selenium nutrition of the oldest-old from these two aspects: to determine the key environmental factors impacting on the content of selenium in crops and to develop the practical technology of efficient utilizing of dietary selenium. The specific objectives of this project are i) to determine the effect of geography landscape differentiation on soil and crop selenium contents; ii) to reveal the activation mechanism of selenium in the rhizosphere microenvironment; iii) to assess the efficiency of nutrition additives (such as vitamin E, ascorbic acid, methionine and other functional foods) on dietary selenium bioavailability under simulated intestinal environment; and iv) to identify the most suitable selenium nutrition promotion technology for the oldest-old by evaluating its applicability and safety. These, in turn, will provide scientific basis for decision making and technical support for improving health and longevity of the elderly population.

改善老龄健康状况的应用基础研究是国家紧迫需要，亦是事关民生福祉的重大战略需求。已有研究证实，硒在防治衰老相关疾病、保障老龄健康等方面发挥着重要作用，但迄今提升高龄老人体内硒营养的相关研究缺乏。针对我国居民膳食硒摄入量总体偏低、高龄老人硒营养流失等现状，本项目拟在我国典型长寿区域开展高龄老人硒营养的环境调控研究。通过综合运用根箱试验、高龄老人肠胃消化的仿真模拟、模式动物实验等研究方法，结合3S技术和数值模型等技术手段，重点研究地理景观分异对土壤-作物硒含量的影响，探讨根际微环境中硒活化的相关机制，分析添加维生素E、抗坏血酸、蛋氨酸等膳食营养素对膳食硒的活化效果，评估硒营养调控方案的适用性。旨在从甄别影响植物性食物硒含量的关键环境因子到探明膳食硒的高效利用机制两个角度，确定改善高龄老人硒营养的切实可行方案，为改善我国高龄老人健康状况和制订老龄健康保障措施提供科学依据。

针对我国居民膳食硒摄入量总体偏低、高龄老人硒营养流失等现状，本项目重点研究地理景观分异对土壤-作物硒含量的影响，探讨根际微环境中硒活化的相关机制，监测添加矿物质、维生素、氨基酸等膳食营养素对膳食硒的活化效果，评估硒营养调控方案的适用性。取得的主要结果包括：①定量分析了海南省地形、植被、土壤等因子对土壤-作物中硒含量的影响，发现土壤中铁和钙的含量显著影响土壤硒的浓度，其中铁含量每增加1g/kg，硒含量增加2.820μg/kg，钙含量每增加1g/kg，硒含量减少3.249μg/kg。②研究了不同外源硒添加情景下小麦根际、非根际土壤硒总量及其形态的动态变化，以及外源硒施加对小麦硒吸收转运和生理代谢等方面的影响。发现低硒水平下（亚硒酸盐≤1mg/kg），根际土壤溶液中无机态硒和总硒的含量随小麦生长而不断增加，高于非根际土壤溶液；高硒水平下（亚硒酸盐≥5mg/kg），根际土壤溶液中无机态硒和总硒的含量随小麦生长而逐渐降低，低于非根际土壤溶液。不同浓度外源硒的施加对小麦生长表现出“低促高抑”的作用，不同时期小麦地下部和地上部的生物量均随外源硒浓度的增加呈现先增后降的趋势，在5mg/kg施硒量时达到最高；小麦叶片谷胱甘肽过氧化物酶的活性随着外源硒浓度的增加呈先升高后下降的趋势，最高值出现在5mg/kg施硒量时；而丙二醛的含量随外源硒浓度的增加呈先下降后增加的趋势，在5mg/kg施硒量时达到最低。③运用体外模拟试验和模式动物实验相结合的方法，探讨了常见膳食补充剂在单一或组合添加方式下对膳食硒的活化效果，发现VE处理和3IN1处理（VE+VC+VB9）对膳食硒的生物可给性具有促进作用；VE、VB9、3IN1处理对鸡的体重和鸡体内硒含量有不同程度的促进作用，其中3IN1处理的促进效果最显著，与此同时，3IN1处理可促进鸡体内超氧化物歧化酶的活性，并显著降低丙二醛的含量。本研究从甄别影响作物硒含量的关键环境因子到建立膳食硒的高效利用技术两个角度，确定改善人体硒营养的方案，研究成果可为改善我国人群硒营养水平提供科学依据。