Serum Selenium and Incident Cardiovascular Disease in the PREvención con DIeta MEDiterránea (PREDIMED) Trial: Nested Case-Control Study

Background: Selenium is an essential trace mineral with potential interest for cardiovascular disease (CVD) prevention owing to its antioxidant properties. Epidemiological data on selenium status and CVD remain inconsistent. The objective of this study was to ascertain whether low serum selenium (SSe) concentrations are related to an increased risk of a first CVD event in a population at high cardiovascular risk. Methods: We undertook a case-control study nested within the “PREvención con DIeta MEDiterránea” (PREDIMED) trial. A total of 207 participants diagnosed with CVD (myocardial infarction, stroke, or cardiovascular death) during the follow-up period (2003−2010) were matched by sex, age, and intervention group to 436 controls by incidence density sampling. Median time between serum sample collection and subsequent CVD event occurrence was 0.94 years. SSe levels were determined using inductively coupled plasma mass spectrometry analysis. Covariates were assessed through validated questionnaires, in-person interviews, and medical record reviews. Conditional logistic regression was used to calculate multivariable-adjusted odds ratios (ORs). Results: Among women, the mean SSe concentration was lower in cases than in controls (98.5 μg/L vs. 103.8 μg/L; p = 0.016). In controls, SSe levels were directly associated with percentage of total energy intake from proteins and fish intake (p for linear trend < 0.001 and 0.049, respectively), whereas SSe concentrations were inversely associated with age, body mass index, and percentage of total energy intake from carbohydrates (p for linear trend < 0.001, 0.008 and 0.016 respectively). In the total group, we observed an inverse dose−response gradient between SSe levels and risk of CVD in the fully-adjusted model (highest vs. lowest quartile: OR = 0.47, 95% CI: 0.27−0.81; ptrend = 0.003). Conclusions: Among elderly individuals at high cardiovascular risk, high SSe concentrations within population reference values are associated with lower first CVD incidence.

The Involvement of Selenium in Type 2 Diabetes Development Related to Obesity and Low Grade Inflammation

BACKGROUND

Effects of the micronutrient selenium have been proposed in obesity and type 2 diabetes mellitus (T2DM) that involve impairments in glucose metabolic pathways and the insulin signaling cascade, mediated through oxidative stress and inflammation. However, the evidence collected to date through animal and epidemiologic studies has been inconclusive. Therefore, in the present study, we aimed to evaluate the relationships of selenium status and inflammation with T2DM and obesity.

METHODS

Participants in the re-survey of the Electricity Generating Authority of Thailand (EGAT)2 study conducted in 2013 (N=655, age 45-60 years) were allocated to three groups based on their body mass index (World Health Organization Asia-Pacific Classification), and their serum selenium and high-sensitivity C-reactive protein (hs-CRP) concentrations and other clinical parameters were compared.

RESULTS

Significant differences in serum selenium and hs-CRP among the groups were associated with differences in fasting blood glucose and glycated hemoglobin, as well as differences in the prevalence of prediabetes or T2DM. The adjusted odds ratios (ORs) (95% confidence intervals) for prediabetes or diabetes were 1.991 (1.318-3.009) and 3.786 (2.087-6.896) for the lowest and highest tertiles of serum selenium concentration in the entire sample and obese participants, respectively. Furthermore, the rising extent of hs-CRP increased the significantly associated with prediabetes or diabetes (adjusted ORs; 2.268 for the entire sample, 4.043 for the overweight and 1.910 for the obesity).

CONCLUSION

Selenium status may be linked to both obesity and T2DM through its effects on signaling pathways. Further nutrigenomic studies are required to clarify the relationship between selenium and metabolic diseases.

Association of dietary and serum selenium concentrations with glucose level and risk of diabetes mellitus: A cross sectional study of national health and nutrition examination survey, 1999-2006

BACKGROUND

The associations among dietary selenium intake, serum selenium concentration, plasma glucose and glycosylated hemoglobin levels, and diabetes risk remain controversial. This study aimed to evaluate these associations in adults from the United States.

METHODS

We conducted a cross-sectional study of participants aged 18 years and older who participated in the National Health and Nutrition Examination Survey. Between 1999 and 2006, a total of 41,474 participants were initially included in this study. Multivariable linear or logistic regression analysis was used to investigate the association between dietary selenium intake and serum selenium concentrations, glucose level, and diabetes risk.

RESULTS

The average age of the participants was 30.32 ± 23.95 years, and 48.72 % were men. Their mean dietary selenium intake and mean serum selenium concentration were 98 ± 55 μg per day and 129 ± 22 ng/mL, respectively. Compared with t he lowest quartile of dietary selenium intake, the highest quartile was associated with elevated plasma glucose levels (β = 2.412, 95 % confidence interval [CI]: 0.420, 4.403, P = 0.018), glycosylated hemoglobin levels (β = 0.080, 95 % CI: 0.041, 0.119, P < 0.001), and diabetes risk (odds ratio [OR] = 2.139, 95 % CI: 1.763, 2.596, P < 0.001). Higher serum selenium was also associated with increased plasma glucose levels (β = 12.454, 95 % CI: 4.122, 20.786, P = 0.003) and glycosylated hemoglobin levels (β = 0.326, 95 % CI: 0.187, 0.465, P < 0.001). A generalized additive model with a spline curve suggested a nonlinear relationship between dietary selenium intake, serum selenium and glucose levels, and diabetes risk.

CONCLUSIONS

Dietary selenium intake and serum selenium were positively associated with elevated levels of plasma glucose and glycosylated hemoglobin, and the relationships were nonlinear. Additional selenium supplementation for patients with diabetes may not be recommended.

Selenoprotein genetic variants may modify the association between serum selenium and oral cancer risk

OBJECTIVE

The relationship between selenium (Se) and oral cancer is still controversial, and the selenoprotein genes play crucial roles in selenium metabolism. We aim to investigate the potential effect of selenoprotein genes (including GPx and TXNRD) in the association of serum Se with oral cancer risk.

METHODS

A case-control study including 235 oral cancer cases and 406 controls from September 2011 to December 2018 was conducted in Fujian, China. The peripheral blood samples were obtained from each participant. Genotyping was performed by MassARRAY system, and serum Se levels were measured by inductively coupled plasma mass spectrometry (ICP-MS).

RESULTS

Compared with the lowest tertile of Se concentration, those with Se levels in the third tertile were associated with the lower risk of oral cancer (OR = 0.228; 95% CI: 0.135, 0.384). After additional adjustment for genetic risk score (GRS, derived from selenoprotein genetic variants), the model demonstrated the superior goodness of fit. When stratified by GRS, the negative correlation of serum Se was more pronounced among those with low risk (i.e., lower GRS). Moreover, there is a multiplicative interaction between serum Se and GRS for the risk of oral cancer (p = .001).

CONCLUSIONS

The present study suggests that serum Se levels may be significantly associated with oral cancer risk, yet the association may be modified by the effects of selenoprotein genetic variants.

Selenium Deficiency Is Widespread and Spatially Dependent in Ethiopia

Selenium (Se) is an essential element for human health and livestock productivity. Globally, human Se status is highly variable, mainly due to the influence of soil types on the Se content of crops, suggesting the need to identify areas of deficiency to design targeted interventions. In sub-Saharan Africa, including Ethiopia, data on population Se status are largely unavailable, although previous studies indicated the potential for widespread Se deficiency. Serum Se concentration of a nationally representative sample of the Ethiopian population was determined, and these observed values were combined with a spatial statistical model to predict and map the Se status of populations across the country. The study used archived serum samples (n = 3269) from the 2015 Ethiopian National Micronutrient Survey (ENMS). The ENMS was a cross-sectional survey of young and school-age children, women and men. Serum Se concentration was measured using inductively coupled plasma mass spectrometry (ICPMS). The national median (Q1, Q3) serum Se concentration was 87.7 (56.7, 123.0) μg L⁻¹. Serum Se concentration differed between regions, ranging from a median (Q1, Q3) of 54.6 (43.1, 66.3) µg L⁻¹ in the Benishangul-Gumuz Region to 122.0 (105, 141) µg L⁻¹ in the Southern Nations, Nationalities, and Peoples’ Region and the Afar Region. Overall, 35.5% of the population were Se deficient, defined as serum Se < 70 µg L⁻¹. A geostatistical analysis showed that there was marked spatial dependence in Se status, with serum concentrations greatest among those living in North-East and Eastern Ethiopia and along the Rift Valley, while serum Se concentrations were lower among those living in North-West and Western Ethiopia. Selenium deficiency in Ethiopia is widespread, but the risk of Se deficiency is highly spatially dependent. Policies to enhance Se nutrition should target populations in North-West and Western Ethiopia.

Injectable organic and inorganic selenium in dairy cows - Effects on milk, blood and somatic cell count levels

Mastitis is the most costly disease of dairy cows. A pro-active approach includes insuring adequate levels of selective trace minerals. The aim of this study was to determine the effect of two different commercially available, injectable selenium products, (sodium) Na-selenite (inorganic) and (selenium) Se-methionine (organic), on milk composition and on serum and milk selenium concentrations in high-yielding Holstein cows on total mix ration. Sixty multiparous cows were randomly selected into three groups of 20, one control group and two groups supplemented with injectable trace minerals. Blood and milk samples were collected over a period of 60 days. No specific change was indicated in milk yield, lactose, milk urea nitrogen (MUN) and milk pH levels compared with baseline values. The Se-methionine supplemented group showed a numerical increase in total milk protein percentage. In the group injected with Se-methionine, a negative correlation was present for the initial 72 hours between serum selenium concentration and somatic cell count (SCC) and a highly significant (p < 0.001) increase in milk selenium concentration for the initial 24 hours. Serum selenium concentration of Se-methionine-supplemented cows was however not significantly changed. Injection of Na-selenite led to a 60-day initial increase in serum selenium concentration above baseline levels and a significant milk selenium concentration on day 1 but to a negative correlation between serum selenium concentration and SCC. Differences in serum and milk selenium concentrations followed with the use of organic and inorganic selenium injectables. Injectable Na-selenite, as selenium, can be of important value for cattle farmers if supplemented on strategically physiological periods to improve production, reproduction and immunity.

Method for measurement of serum copper, zinc and selenium using total reflection X-ray fluorescence spectroscopy on the PICOFOX analyser: Validation and comparison with atomic absorption spectroscopy and inductively coupled plasma mass spectrometry

BACKGROUND

Total reflection X-ray fluorescence is a comparably new method for the measurement of trace elements in biological samples.

METHODS

Results obtained by total reflection X-ray fluorescence were compared to atomic absorption spectroscopy for Cu and Zn and inductively coupled plasma mass spectrometry for Cu, Zn and Se in patient serum. The total reflection X-ray fluorescence assay was characterized for accuracy; recovery; intra- and inter-assay imprecision (using patients' samples, external quality assurance and quality control materials); limit of blank; limit of detection; linearity; interference and stability of prepared samples.

RESULTS

Minimal sample preparation is required for total reflection X-ray fluorescence and simultaneous multi-elemental analysis is possible in clinical samples. There was a small positive bias for Cu and Zn measurements using total reflection X-ray fluorescence compared to atomic absorption spectroscopy and inductively coupled plasma mass spectrometry and a significant negative bias for Se measurements by total reflection X-ray fluorescence relative to inductively coupled plasma mass spectrometry. Recovery, imprecision and linearity were acceptable. The limit of detection was shown to be 1.2  μmol/L for serum Cu, 1.8  μmol/L for serum Zn and 0.2  μmol/L for serum Se.

CONCLUSIONS

Measurement of Cu and Zn in serum samples using total reflection X-ray fluorescence would be a viable alternative to atomic absorption spectroscopy or inductively coupled plasma mass spectrometry. The volatility of some Se compounds results in lower Se results being reported using total reflection X-ray fluorescence and further work would be necessary to identify whether total reflection X-ray fluorescence has an acceptable clinical sensitivity and specificity for the assessment of Se deficiency. Measurement of copper, zinc and selenium on whole blood samples is possible using total reflection X-ray fluorescence which may provide a more accurate assessment of trace element deficiency for patients with an acute phase response.

Serum levels of Selenium and C-reactive protein in comatose patients with severe traumatic brain injury during the first week of hospitalization: case-control study

Introduction

Mortality and morbidity related to traumatic brain injuries still remain high in patients. Many authors reported the importance of Selenium in maintaining the integrity of brain functions. This fact is supported by clinical evidence that therapy with selenium supplementation could help patients suffering from brain disorders like neurodegenerative diseases. The aim of our study was to assess the relationship between Selenium concentration in serum and evolution of comatose patients with severe traumatic brain injury, in the first week of admission, and the correlation between selenium and C-reactive protein.

Methods

This case-control study was conducted with 64 comatose patients with TBI, in the Department of Anesthesiology and Reanimation, IbnSina University Hospital and Hospital of specialties in Rabat-Morocco, and healthy volunteers recruited in Blood transfusion center of Rabat. Blood sampling was collected from TBI patients, in the first week (3h after admission and each 48h during one week), and from healthy volunteers one time. Concentration of Se in serum was determined by electrochemical atomic absorption spectrometry. Statistical analysis was performed using Statistical software (SPSS) and the cases and controls were compared using the Mann-Whitney U test. A P-value < 0.05 was considered to be statistically significant.

Results

Comparison selenium concentration in the first day (D0), third day (D2) and fifth day according to the death and survival statue in patients did not show statistical significance (p > 0.05). Selenium concentration of D0 in patients and Selenium concentration in control group also did not show statistical significance (p > 0.05). Similarly, we did not report a correlation between selenium and C-reactive protein.

Conclusion

According to our data selenium and CRP may not play a role in progression of coma state in patients with severe traumatic brain injury.

Serum selenium and skin diseases among Nigerians with human immunodeficiency virus/acquired immune deficiency syndrome

Background

The role of selenium as an antioxidant micronutrient has garnered the unprecedented focus of researchers in recent times. No clinical study has related serum selenium concentration to skin diseases in human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) patients.

Methods

In this study, 134 newly diagnosed HIV patients that satisfied the inclusion criteria were included. Skin diseases were clinically diagnosed and fasting venous blood was taken for assessment of serum selenium using an atomic absorption spectrophotometer.

Results

The mean age of HIV subjects with and without skin disease were not significantly different: 32.72 ± 9.21 versus 35.86 ± 8.55 years, P = 0.077, respectively. The mean of serum selenium (0.51 ± 0.48 versus 0.81 ± 0.39), CD4+ count (228.06 ± 212.89 versus 446.41 ± 182.87), and body mass index (BMI; 21.09 ± 3.58 versus 23.53 ± 3.35) were significantly lower (P < 0.001) for HIV/AIDS participants with skin disease than those without skin disease. We found significant clustering of symptoms and signs: fever (P = 0.037), weight loss (P = 0.009), oral candidiasis (P = 0.038), pallor (P = 0.037) among HIV/AIDS subjects with skin diseases than those without. Low serum selenium concentration was significantly associated with primary skin disease of HIV/AIDS, such as pruritic papular eruption of AIDS (P = 0.003), xeroderma (P = 0.030), fluffy hair (P = 0.021), blue-black nail hyperpigmentation (P = 0.033) and secondary skin disease, such as oral candidiasis (P = 0.002). There was a significant association between low serum selenium concentration and increasing frequency of skin diseases (P = 0.002), but serum selenium was not significantly related to extents of distribution of skin diseases (P > 0.05).

Conclusion

serum selenium concentration was lower among HIV subjects with skin diseases than those without skin disease. Pruritic papular eruption, xeroderma, fluffy hair, blue-black nail hyper pigmentation, and oral candidiasis were significantly associated with low serum selenium concentration.

Serum selenium levels in chronic lymphocytic leukemia

BACKGROUND

Selenium is a trace mineral which has the role of multiple biologic functions. In free-living animals and humans, selenium is mostly in the form of two selenium-containing amino acids as selenocysteine and selenomethionine. The present study aimed to obtain more data on the relationship between serum selenium in chronic lymphocytic leukemia (CLL).

MATERIALS AND METHODS

Serum selenium levels were measured in 51 patients with chronic lymphocytic leukemia (CLL) as patients group and in 40 non-hospitalized healthy individuals as control group.

RESULTS

Selenium was recognized by atomic absorption spectrometer. Decreased mean serum selenium concentrations were observed in the group with chronic lymphocytic leukemia as compared to normal ones (P = 0.005). Serum selenium concentrations were examined in stages 0 and I. They observed a significant difference between the mean serum concentrations of selenium in stage 0, I and II and that of stage IV and V patients with CLL (P = 0.01). The groups were compared and significant differences were observed i.e., low serum selenium levels in the stage III and IV CLL (P = 0.001). The second selenium test was designed in 21 out of 48 patients within 10 weeks from the beginning of chemotherapy. Serum selenium concentration was tested again in 21 patients, and significant differences have been observed between the time before the treatment and after it (P = 0.02).

CONCLUSIONS

Our results show that in patients with CLL the mean serum selenium levels are lower than that of normal.

Selenium status in a group of schoolchildren from the region of Madrid, Spain

BACKGROUND

To assess the selenium status of a group of schoolchildren from the Region of Madrid, Spain.

METHODS

Study subjects comprised 483 children (216 boys and 267 girls) aged between 8 and 13 years. Selenium intake was determined using a 3-day food record. The foods consumed were transformed into energy and nutrients, and the selenium intake was compared with that recommended. Serum selenium levels were also recorded.

RESULTS

Mean (SD) selenium intake [91.0 (25.2) μg day(-1) ] was above the recommended level in 99.4% of subjects; the main dietary sources were cereals, meats, fish and milk products. The serum selenium concentration [mean (SD) 71.1 (14.4) μg L(-1) ], however, was <60 μg L(-1) in 13.9% of subjects, and <45 μg L(-1) in 5.6%. The serum selenium concentration correlated with the selenium intake (r = 0.169; P < 0.05). Children with a serum selenium concentration of <75 μg L(-1) had significantly smaller selenium intakes than those with a serum concentration of ≥75 μg L(-1) .

CONCLUSIONS

Although selenium intake was generally above that recommended, the serum selenium concentration of the children could be improved. This could be achieved by increasing the relative consumption of cereals and other selenium rich foods such as fish.