| Selenium is an essential trace elements. Selenium deficiency and excess will have adverse effects on human health. Enshi area is typical high-selenium area in China, and Suzhou is located in China low-selenium areas. Studies on daily selenium dietary intake in these two areas, finding out the selenium contents in foods, helping to assess the safety of dietary nutrition.By the method of acid digestion and atomic fluorescence spectrophotometry, the content of selenium of the diet food in Enshi Shadi area and Suzhou City were calculated. We calculated the daily dietary selenium intake of Enshi Shadi area and the residents of Suzhou City. The results showed that for the Enshi Shadi area, the selenium content of rice (1.059±0.802μg/g) is more than the maize's (1.059±0.802μg/g); in vegetables, green beans had the highest selenium content (1.57±1.06 )μg/g; The content of selenium of chicken and eggs was (1.72±1.04)μg/g and (2.26±1.12)μg/g. For Suzhou, animal food eggs (151.7±48.7)μg/kg and pork (150.3±16.6)μg/kg had the highest content of selenium which higher than the chicken and duck meat, fish (grass carp) and beef ; Foodgrain had similar selenium content. Rice was (23.6±6.2)μg/kg, flour was (21.2±3.7)μg/kg; The selenium content of fruits and vegetables are low, the highest selenium content of vegetables was shiitake mushroom (76.1±23.7)μg/kg. The highest selenium content of fruit was banana (3.21±1.43)μg/kg.The selenium intake of residents of Enshi Shadi area was(720.6±260.8)μg/d. Among them, there was the risk of selenium poisoning of Laoxiongpo resident who intake more selenium(1044.8μg/d), Residents of Beifengya intake selenium (710.4μg/d), and Sangshupo residents daily intake of selenium were more than recommended values (530.9μg/d), close to the maximum security area of daily selenium intake. Rice was the largest contribution of the dietary selenium intake of residents in Beifengya and Laoxiongpo but the largest values of dietary selenium intake of Sangshupo were vegetables, followed by rice and meat (chicken meat) food. In addition, corn, soybeans and tuber foods had small contribution to dietary selenium intake of local residents.Suzhou City, the average selenium intake of residents was(43.9±3.8)μg/d, of which the greatest contribution was animal foods, accounting for 67.9%, plant foods on the contribution of selenium intake was 32.1%. Among them, fish and pork account for more than 19%, cereals contributed 22.6% which was resident's main food; vegetable was necessary for the residents, but the contribution of selenium was only 9.3%; fruit accounted for 0.3% which had little effect of residents selenium intake. Suzhou residents selenium intake can basically meet the physiological needs, but slightly lower than 50μg/d which the daily minimum selenium intake recommended by the Chinese Nutrition Society.The selenium content of residents in Beifenya (BFY) was (2.89±1.04)μg/g, Sangshupo(SSP) for (3.08±1.76)μg/g, while the selenium level of residents′hair in Laoxiongpo(LXP) was (5.00±2.38)μg/g; The mean value of selenium content in residents in Suzhou was 358.7μg/kg, range from 124.3 to 684.7μg/kg. Sex influence on the selenium content in the hair, for Enshi shadi area, selenium content in female hair was significantly higher than of male (P <0.05), three sampling points were obtained the similar results; while the residents of Suzhou City, found that for men the selenium content of hair was significantly higher than female (P <0.05). But the effective of the age on selenium content of hair in the two regions was not very significantThe correlation between the selenium level of rice and the residents′hair selenium content was analyzed in Enshi shadi area. The results showed that in Beifengya and Lao Xiong, the level of local residents′hair and the selenium content of rice was in a positive correlation, but correlation is poor (rBFY = 0.2867, rLXP = 0.0412); the slope for the residents′hair selenium and selenium content of rice was in a negative correlation (rSSP = 0.2523) in Shangshupo.There′s a primary model was established which based on a random sampling to predict the dietary selenium intake of local residents. For female the daily Se intake = 0.0887 Sehair + 16.1 (R2=0.9798, n=7), and for male the daily Se intake = 0.0803 Sehair + 14.2 (R2=0.9367, n=7). These regression models can be used to predict the local residents'daily Se intake through their hair Se content. The results showed a good linear relationship between daily Se intake and hair Se content, which was suitable for Suzhou.In addition, a new method utilizing enzymatic to extraction the different selenium species of corn and rice samples. The effective of extraction rate was 60%, and the recovery rates were 115.9 ~ 124.4%. Using this method to analysis the different selenium species of the corn and rice which had high selenium contents in Enshi Shadi area. The results showed that the main form of selenium species was selenomethionine (SeMet) both of the corn and rice, which content 15% and 10% of the total selenium, respectively. As the limitations of the separation and detection technology, there are many unknown selenium compounds to be studied further.
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