| 1. ObjectiveTaigu county, Shanxi province, is an selenium-adequate area. Serum selenium levels of healthy people in this area were detected to understand the present nutrition status of selenium better and provide the basic evidences for scientifically guiding the selenium supplementation of residents there or alike and launching nutrition intervention to prevent chronic diseases with selenium in the future. Based on the suggestion that Se-enriched garlic may eradicate Helicobacter pylori (HP) from data of preclinical research and pilot application, a number of subjects from two neighbouring villages, had similar living habits and dietary pattern, infected refractory HP without any clinical symptom, once failed to eradicate HP by quadruple chemotherapy in Linqu, Shandong province, were select to enroll the other project of the study, and the effect of HP eradication with Selenium-enriched garlic (Se-G for short, the same as the followings) capsules were observed, some selenium-related indexes in blood samples were detected in order to find the adequate selenium-related indexes and their change rules for evaluating selenium nutrition status of subjects with Se-G capsules supplementation, providing some laboratory evidences and practical evaluation indexes of selenium nutrition status, which can basically meet the requiremend of nutrition intervention studies with Se-G in rural area, for related researches in the future. 2. Methods(1)A total of 793 subjects were recruited by random sampling from people engaged in service sectors in Taigu County, Shanxi province, which was Se-G production base. Information about gender, age, occupation and educational level was collected and 2ml serum, which was remained by health examination, was collected after getting their consent. The content of serum selenium was measured by fluorospectrophotometry after these serum samples, frozen by dry ice, were transported in low temperature to Institute for Nutrition and Food Safety, Chinese Center for Disease Control and Prevention (CDC). All data were statistically analyzed by independent-sample t test or analysis of variance, which was 2-tailed andα=0.05,with SPSS software version 13.0.(2)A total of 20 subjects aged 39-56 years from two neighbouring villages, who had similar living habits and dietary pattern, no selenium supplementation history, good compliance and normal function of liver and kidney, no other severe background diseases, infected refractory HP without any clinical symptom, were selected from people who were once failed to eradicate HP with quadruple chemotherapy. All participants had positive results determined by 13C-Urea Breath Test (13C-UBT). Participants were asked to take capsules after meals in front of field staff, two times a day, day and night respectively,4 capsules each time, and equal to supplement selenium of Se-G 168μg (selenium based, the same as the followings) every day. All the participants received orally for 30 days therapy with Se-G capsules and a 13C-UBT to assess the eradication of HP at the 44th day of the post-treatment, if the rate was>0.4%, it was regarded as a positive result.4 ml venous blood were taken, anticoagulated by EDTA, separated at 3000r/min in low temperature centrifuge at the day of Se-G supplementation, as well as the next day of finishing the Se-G supplementation and the 44th day after finishing the Se-G supplementation, respectively. Plasma and red blood cell were kept in freezing tubes quick frozen by liquid nitrogen or dry ice, transported to our laboratory, stored, in -20℃fridge. The selenium levels of plasma and red blood cell were measured by the fluorospectrophotometry; the activities of plasma and red blood cell were measured by DTNB method; the MDA levels of plasma and red blood cell were detected with MDA kit. All data were statistically analyzed by repeated measures of variance witha=0.05,using SPSS software version 13.0. If the difference was significant, multiple comparisons in three time points were needed. Each categorical factor was also analyzed to see if there was any effected on each selenium-related index. Before implementation, all study proposals had to be approved by ethical committees.3. Results(1)The age distribution for these samples ranged from 20 to 67 years old. The average serum selenium and standard deviation(SD) was 0.0913±0.0186μg/ml, 0.0947±0.0184μg/ml and 0.0887±0.0184μg/ml for total, male and female, respectively, and serum selenium level of male was significantly higher than that of female. There were no significant differences of serum selenium levels in each group of different age, occupation, and educational levels. Serum selenium levels in male were significantly higher than in female in both 20-29 y group and 30-39 y group, but there were no significant differences in groups older than 40y.In 30-39 y group, male had the highest serum selenium, but female occurred just the opposite. There was a decrease of serum selenium in male older than 40, but a great increase in female.(2)In the HP eradication study of Shandong, the eradication rate was 20% among 20 subjects after taking Se-G capsules. In three time points, the day of Se-G supplementation, the next day of finishing the Se-G supplementation and the 44th day after finishing the Se-G supplementation, the plasma GPx activities increased steadily, while red blood cell GPx activities declined steadily. The plasma MDA levels declined significantly after Se-G capsules supplementation, and then increased when withdraw. The differences of the red blood cell MDA levels were not significant in three time points. There was a sensitive dose-effect relationship for plasma selenium in three time points, in other words, plasma selenium increased at first, and then decreased, along with Se-G capsules supplementation and withdraw. The selenium from Se-G could more largely accumulate in red blood cells than in plasma, and the decrease of red blood cell selenium was not significant after stopping taking capsules. The mean plasma selenium level of these subjects before treatment was 0.0729±0.01458μg/g, which was lower than that of healthy people in Shanxi province.Compared with subjects who failed in HP eradication with Se-G capsules, subjects who succeed had low plasma and red blood cell GPx activities, red blood cell MDA levels, plasma and red blood cell selenium levels. Factors, such as sex, age groups and villages, had no effects on all selenium-related indexes and their change trends.4. ConclusionThe serum selenium level of adults in Taigu county is adequate, but compared with progressed areas in the world, it can be categorized as low-middle level; serum selenium levels in male of 20-40 years old are significantly higher than in female, but the differences turn to be narrow in people older than 40 years old. But, totally, serum selenium level in male is higher than in female.From the analysis of the plasma selenium levels, subjects from Shandong province have adequate selenium nutrition. Se-G capsules can eradicate refractory HP infection with a certain rate. There supposed to be a phenomenon that elder subjects who have low plasma and red blood cell GPx activities, red blood cell MDA, plasma and red blood cell selenium levels would get more benefits from HP radication. Plasma selenium level can reflect the change of selenium in human body exactly, so it can be used to monitor compliance of subjects who supplement selenium wit Se-G capsules and as a sensitive evaluation biomarker of short-time selenium nutrition status; Agreement with the findings in animal experiments, the red blood cells in people may be one of reservoir pools of selenium from Se-G.More studies are needed to confirm the change trend of each selenium-related index.
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