Spatial variations in soil selenium and residential dietary selenium intake in a selenium-rich county, Shitai, Anhui, China

Authors: LONG, ZEDLONG - University Of Science And Technology Of China; YUAN, LINXI - University Of Science And Technology Of China; HOU, YUZHU - Jiangsu Normal University; Banuelos, Gary; LIU, YONGXIAN - Guangxi Academy Of Agricultural Sciences; PAN, LIPING - Guangxi Academy Of Agricultural Sciences; LIU, XIAODONG - University Of Science And Technology Of China; YIN, XUEBIN - University Of Science And Technology Of China

Submitted to: Journal of Trace Elements in Medicine and Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2018
Publication Date: 12/1/2018
Citation: Long, Z., Yuan, L., Hou, Y., Banuelos, G.S., Liu, Y., Pan, L., Liu, X., Yin, X. 2018. Spatial variations in soil selenium and residential dietary selenium intake in a selenium-rich county, Shitai, Anhui, China. Journal of Trace Elements in Medicine and Biology. 50:111-116. https://doi.org/10.1016/j.jtemb.2018.06.019.
DOI: https://doi.org/10.1016/j.jtemb.2018.06.019

Interpretive Summary: Selenium (Se) is an essential trace element for human beings. Since Keshan disease in northeast China was shown to be linked to Se deficiency, Se has received increasing worldwide attention. Researchers have studied the distribution of Se in elderly persons in China and determined that Se-deficient counties in China in which people experience Keshan diseases tended to have the fewest elderly populations compared to Se-sufficient counties. In China, Dashan village in Shitai County (Anhui) is known as a longevity village. In addition, the rates of cancer are very low and the percentage of elders (>80 years) is high (about 12% of the total population). To explore the potential relationship between longevity and naturally occurring Se in Shitai County, the Se content in Shitai’s food chain (including soils and foods) were determined and the daily Se intake and hair Se content were calculated for the residents in Shitai and in other near-lying villages. Based on this study, soil Se levels could be classified as Se rich in Dashan. Thus, the Se concentrations of most foods produced in Dashan were also high. The daily Se intake of Dashan residents reached 298.4 µg/d/adult, which was 6–10 times higher than that at other village study sites, and 5 times higher than the current recommended Se intake values in China (60 µg/d/adult). Although a significant positive correlation was found between soil Se content and longevity indexes by some researchers, there are still few data available comparing longevity and Se-nutrition under natural field conditions. Thus, the present study demonstrated that the study site, Shitai county, had significant variations in Se levels of soils, foods, and resident dietary intakes, and the region should be used as a natural laboratory to continue to investigate the relationship between Se and human health.

Technical Abstract: Shitai, a selenium (Se)-rich county in Anhui, China, has been reported for its resident longevity in the last 20 years. A recent survey by the Anhui Bureau of Geological Survey showed that soil Se content in the Shitai area ranged from 0.05 to 51.20 mg/kg, with an average of 0.56 mg/kg. To explore the potential relationship between longevity and natural-occurring Se content in Shitai County, Se concentrations were determined in Shitai’s food chain (including soils and foods) and the daily Se intake and hair Se content were calculated for the residents. In the present study, 33 soil samples, 66 food samples, and 82 hair samples were randomly collected from field sites, local food markets, and male and female residents in Shitai and in four nearby villages (Dashan, Xianyu, Yongfu and Yuantou). The total Se content in all samples and the levels of water soluble, exchangeable, acid soluble, organic bound, and residual Se in soil samples were determined with hydride generation - atomic fluorescence spectrometry. The total Se content in soil ranged from 227 to 2603 µg/kg, with the averages of 1607 ± 242 µg/kg in Dashan, 1149 ± 118 µg/kg in Xianyu, 521 ± 157 µg/kg in Yongfu, and 363 ± 140 µg/kg in Yuantou. The soil bioavailable Se content (soluble and exchangeable Se) in Dashan was highest (14.98%), followed by Xianyu (13.69%), Yongfu (13.18%) and Yuantou (9.38%). For food samples, the highest Se concentration of grains was 468.5 µg/kg in Dashan, while lowest concentration of Se was observed in Shitai (41.7µg/kg). The estimated daily Se intake of residents in Dashan reached 298.4 µg/d/adult, which is about 5 times higher than the recommend nutrient intake in China (60 µg/d/adult), and 6–10 times higher than the levels observed in Xianyu (47.6 µg/d/adult), Yuantou (46.1 µg/d/adult), Yongfu (40.0 µg/d/adult), and Shitai (30.0 µg/d/adult). Although hair Se content in residents of Dashan (male: 709.2 µg/kg; female: 589.2 µg/kg) was significantly higher than those at the other village study sites, no significant relationships were observed between daily Se intake and hair Se content. Although the present study demonstrated that Se levels in soils, foods, resident dietary intake, and human hairs varied significantly in Shitai County, the region is still invaluable as a natural laboratory to study the direct relationship between Se and human health.