Benefit-Risk Assessment On Quality And Safety Of Selenium-Rich Agro-Food And Research On The Mechanism Of Metal-Associated Effect In Selenium-Rich Agro-Food

Selenium(Se)is an essential trace element for humans.The human body cannot synthesize or reserve selenium and needs to obtain selenium from their diets.Consumption of selenium-rich agro-food has become a way to improve the selenium deficiency of human.The reported studies have shown that insufficient or excessive intake of selenium is harmful to human health.China is a country with severe selenium deficiency.About 500-600 million people are in the low-selenium state due to insufficient selenium intake from the diet.However,selenium poisoning also occurred in selenium-rich areas such as Ankang in Shanxi Province and Enshi in Hubei Province.Market research found that the quality of selenium-rich agro-food is currently uneven,and there are many untrue propagandas.At the same time,a large number of studies have proved that there is metal associated phenomenon in selenium-rich agro-food,which affects the quality and safety of selenium-rich agro-food and poses a potential threat to human health.Therefore,it is urgent to clarify the quality status of selenium-rich agro-food,to evaluate the dietary selenium and potential associated metals intakes of Chinese the benefit-risk effect of selenium-rich agro-food,to analyze the influencing factors of selenium and its associated metals in selenium-rich agro-food,and to reveal the associated mechanism with metals in selenium-rich agro-food to guide the development of selenium-rich agro-food.In this study,15 major selenium-rich agro-food groups and their common counterparts,which are in the dietary structure of the Chinese population,were selected as research objects.Multiple analytical methods,benefit-risk assessment,multiple linear regression,and transcriptomics were used.The purpose was to analyze the distribution of selenium and its associated metals in selenium-rich agro-food and assessment the benefit-risk of selenium-rich agro-food.Models for the prediction of the accumulation of selenium and its associated metals in typical selenium-rich agro-food were established.The association mechanism with metals in selenium-rich rice was explored.This study has laid a foundation for the consumption and production of selenium-rich agro-food.The main results of this study are as follows:1.To study the quality and the distribution of selenium and associated metals in selenium-rich agro-food,15 categories of selenium-rich agro-food samples and their common counterparts from seven common areas,two selenium-rich areas,and one selenium-deficient area in China were collected and analyzed.The results showed that the selenium content of the selenium-rich agro-food varies greatly,and the overall pass rate of selenium-rich agro-food on the market was only 24.24%.The types of selenium-rich agro-food with higher selenium content were cereals,livestock and meat,edible fungus algae,eggs,and tea(P<0.01).Meanwhile,the associated metals content of these agro-food was also relatively higher(P<0.01).Overall,the detection rate and content of associated metals in selenium-rich agro-food were higher than those of their common counterparts(P<0.01).2.Based on the selenium and associated metal contents of selenium-rich agro-food and their common counterparts,the dietary selenium and associated metal intakes of different population groups with different dietary scenarios were calculated,and their benefit-risk were assessed to evaluate the quality of selenium-rich agro-food by using Monte Carlo simulation technology.The results showed that the consumption of selenium-rich agro-food was an effective way to supplement selenium.When selenium-rich agro-food was consumed,the dietary selenium intake of all population could reach their recommended intakes(RDIs).However,it is necessary to pay attention to the intake of chromium,cadmium,and arsenic from selenium-rich agro-food.3.The selenium-rich rice,garlic,black fungus,and eggs were used as research objects and large-scale group sampling of soil/matrix/feed,irrigation water/feeding water and selenium-rich agro-food in the main production areas were performed.The associated metal in typical selenium-rich agro-food was screened by using Pearson association analysis and the main factors affecting the accumulation of selenium and its associated metals were analyzed with stepwise regression analysis in selenium-rich agro-food.The results showed that the associated metal in selenium-rich rice and selenium-rich garlic was cadmium,and the main factors affecting selenium and cadmium accumulation in rice and garlic were soil p H,soil organic matter content(SOM),and total selenium and cadmium contents in soil.The associated metal in selenium-rich black fungus was chromium,and the main factors affecting the accumulation of selenium and chromium in black fungus were the matrix organic matter content(MOM),the total amount of selenium and chromium contents in the matrix.The associated metal in the selenium-rich eggs was chromium,and the main factor affecting the accumulation of selenium and chromium was the total amount of selenium and chromium contents in the feed.4.Based on the relationship between the total amount of selenium and its associated metal in soil/matrix/feed,soil p H and SOM/MOM,and the content of selenium and associated metals in typical ago-foods,models for predicting the accumulation of selenium and its main associated metals in typical selenium-rich agro-food were deduced by using multiple regression analysis methods.For example,the prediction models of selenium and its associated metal(cadmium)accumulation in selenium-rich rice were:lg(Se_rice)=-0.1983+0.1022 lg(Se_soil)+0.1697 lg(p H_soil)+0.7545 lg(SOM)and lg(Cd_rice)=-0.1748+0.8605 lg(Cd_soil)-0.1695 lg(p H_soil)+0.3581 lg(SOM).The established models were proved to be rational and reliable.5.According to transcriptome analysis,a metal-associated mechanism based on the selenium-cadmium transporter and ascorbic acid-glutathione metabolic pathway in selenium-rich rice is proposed:the expression of phosphate transporter and sulfuric acid transporter genes in selenium-rich rice is up-regulated to promote the absorption of selenium,the up-regulated expression of genes encoding NRAMP,ZRT and IRT will increase the absorption of cadmium.At the same time,in selenium-rich rice,the key genes of the ascorbic acid-glutathione metabolic pathway were up-regulated,and the expression of antioxidant enzyme genes was up-regulated,resulting in the association of cadmium and selenium.In summary,selenium-rich agro-food can be used as an effective selenium supplementation method to improve the dietary selenium intake for humans.However,it is necessary to pay attention to the excessive intake of chromium,cadmium,and arsenic in selenium-rich agro-food.The accumulation of selenium and its associated metals in selenium-rich agro-food is affected by the physical and chemical properties of the soil and the total amount of the corresponding elements in the soil.Prediction models for the accumulation of selenium and associated metals in selenium-rich agro-food has been established.Transcriptome results explained that selenium-rich rice upregulates the expression of phosphate transporters and other genes,resulting in the cadmium-associated effect.This study will provide a direction for the production of safer selenium-rich agro-food.