Bioavailability Of Selenium In Chinese Se-Rich Rice

Selenium?Se?is an essential micronutrient for human.Rice is one of important cereal crops in China,it is an important way for the body to supplement various nutrients.Selenium-rich rice has become one of the main selenium-rich agricultural products in China,It is considered a safe and effective source of Se intake for humans.There are many kinds of commercial Se-rich rice in China,but the unified standardization is not yet formed for the Se concentration of rice.The Se concentration of rice does not fully reflect the Se bioavailability,the bioavailability of Se is one of the important guide lines used for estimating Se-rich rice nutrition quality,it related to the Se concentration and species.The study is aimed to study on the Se bioavailability of Se-rich rice,offers scientific and technical support to establish the method for evaluating the bioavailability of Se for the Se-rich rice,and establishing the standard for Se concentration of rice.The SD rats were used to animal model in this study,and the best fit target organ of Selenium in rats was choice,the method for evaluating the relative bioavailability?RBA?of Se in rice based on rat model what was established.The Se concentrations and Se form of Se-rich rice for the Chinese market was detected by ICP-MS and HPLC-ICP-MS.The RBA of Se-rich rice which from across China was evaluated by the method that base on the rats model.The relation between Se RBA and Se concentrations or Se form was expounded.Finally,based on the daily rice consumption of residents and the RBA of Se in rice,the contribution of Se in rice to human intake of Se in China.The Results As Follow:?1?The SD rats were fed to the dietary with different concentrations of selenite,then the concentrations of Se of liver,kidney,serum and the content of Se of urine were detected,the dose-response curve of Se-target organ was established,The dose of ingested Se showed a strong correlation with the Se concentration or content in the target organ?R²=0.75-0.87?,of which the correlation was highest when urine was used as the target organ?R²=0.87?,followed by the liver+kidney meeting the target organ?R²=0.86?,therefore,it is recommended that urine is suitable as a target organ?biomarker?for evaluating the relative bioavailability of Se.?2?The Se RBA of Se-rich rice was evaluated by the method that based on rat model,urine was the target organ.It shows that the Se RBA of 16 kinds of Se-rich rice was 41.71-102.29%,the difference in Se RBA of Se-rich rice is about 2.5 times.The relation between the Se RBA and Se concentrations,Se form was calculated,there was no significant correlation between the Se concentrations in rice and Se-RBA?p>0.05?.The proportion of Se Met in rice showed a significant positive correlation with Se-RBA?p<0.05,R2=0.432?.It can be seen that there are differences in the Se-RBA in different rice,which is affected by the form of Se.It is worth noting that the Se-RBA in rice is not significant with its Se concentrations.Therefore,in order to accurately reflect the nutritional of Se in rice in human body,it is particularly important to evaluate the Se-RBA in rice.?3?The average of Se concentration of commercial Se-rich rice in China is0.116±0.114 mg/kg,the range of Se concentration commercial Se-rich rice was 0.061±0.045-0.154±0.153 mg/kg,The highest is in central China and the lowest is northeast.The Se concentration of some commercial Se-rich rice doesn't meet the Chinese standards for Se-rich rice?0.04-0.3 mg Se/kg?,rice with Se concentration below 0.04 mg Se/kg accounted for 54.6%of the total sample,rice with Se concentration greater than 0.3 mg Se/kg accounted for10.7%.The Se concentration of most the standard rice in range of 0.04-0.15 mg Se/kg.It is indicated that the Se concentration of Se-rich rice in Chinese market is too low or exceeds the standard,It is necessary to strengthen the Se concentration detection and the supervision and management of production and sales.The Se species in rice was analyzed by HPLC-ICP-MS,and the Se form in rice is mainly Se Met,accounting for 66.7-96.5%of total Se,the second one is Se?VI?,accounting for 3.9-24.1%,and the Se Cys₂ accounting for 2.9-16.4%.It can be seen from this that due to the differences in the Se concentrations in the soil of the rice producing area,the adoption of different Se-rich technologies,different cultivars and other factors,there is a large difference between the selenium content and selenium forms of Se-rich rice on the Chinese market.?4?The calculation of dietary intake of Se in rice based on the Se concentrations and the Se-RBA.The results show that the Se intake calculated based on the total method was:North China 8.42-23.99?g/d,Northeast4.43-2.61?g/d,East China 9.58-27.30?g/d,Central China:11.18-31.85?g/d,South China 9.00-25.64?g/d,Southwest 7.99-22.75?g/d,Northwest 4.65-13.24?g/d.The Se intake calculated based on the Se-RBA was 5.28-15.03?g/d in North China,2.77-7.61?g/d in Northeast,6.00-17.10?g/d in East China,7.00-19.95?g/d in Central China,5.64-16.07?g/d in South China,Southwest5.00-14.25?g/d,Northwest 2.91-8.29?g/d.The selenium intake of selenium-enriched rice in all regions did not reach the recommended nutrient intake?RNI?.There was low Se intake based on Se-RBA method.The recommended nutrient intake?RNI?and the tolerable upper intake level?UL?were used to be the indicators,and assessed the risk of Se intake through the target hazard quotient?THQ?.The result showed that the Se intake of people eating Se-rich rice was far less than the UL?THQ<1?.That the average value of62.65%?41.71-102.29%at 95%confidence interval?of the Se-RBA of Se-rich rice was uesed to assessed the RNI and UL with different group of people,the result showed that the Se concentration of Se-rich rice required by residents of different genders and ages is different,between the ages of 2 and 70,male and female should take in the Se-rich rice with the concentration of 0.46-0.64 mg/kg and 0.49-0.75 mg/kg,repectively,so that the Se intake through rice would be reach the RNI.Moreover,the people from different group shuold take in the Se-rich rice with the concentration of 2.02-4.24 mg/kg?male?and 2.02-4.99mg/kg?female?,that to control the Se intake was low than UL.It can be seen that the national standards and some local standards of Se concentration of Se-rich rice in China may have low problems.That people eating Se-rich rice may have insufficient Se intake.This result provides a scientific basis for in-depth understanding and mastering the dietary nutrition of Se in Se-rich rice in China and the reasonable formulation of selenium standards for Se-rich rice.