Selenium intakes in 18-64-y-old Irish adults

Urinary metal profiles in mother-offspring pairs and their association with early dysglycemia in the International Hyperglycemia and Adverse Pregnancy Outcome Follow Up Study (HAPO-FUS)

BACKGROUND

Variations in dietary intake and environmental exposure patterns of essential and non-essential trace metals influence many aspects of human health throughout the life span.

OBJECTIVE

To examine the relationship between urine profiles of essential and non-essential metals in mother-offspring pairs and their association with early dysglycemia.

METHODS

Herein, we report findings from an ancillary study to the international Hyperglycemia and Adverse Pregnancy Outcome Follow-Up Study (HAPO-FUS) that examined urinary essential and non-essential metal profiles from mothers and offspring ages 10-14 years (1012 mothers, 1013 offspring, 968 matched pairs) from 10 international sites.

RESULTS

Our analysis demonstrated a diverse exposure pattern across participating sites. In multiple regression modelling, a positive association between markers of early dysglycemia and urinary zinc was found in both mothers and offspring after adjustment for common risk factors for diabetes. The analysis showed weaker, positive, and negative associations of the 2-h glucose value with urinary selenium and arsenic respectively. A positive association between 2-h glucose values and cadmium was found only in mothers in the fully adjusted model when participants with established diabetes were excluded. There was a high degree of concordance between mother and offspring urinary metal profiles. Mother-to-offspring urinary metal ratios were unique for each metal, providing insights into changes in their homeostasis across the lifespan.

SIGNIFICANCE

Urinary levels of essential and non-essential metals are closely correlated between mothers and their offspring in an international cohort. Urinary levels of zinc, selenium, arsenic, and cadmium showed varying degrees of association with early dysglycemia in a comparatively healthy cohort with a low rate of preexisting diabetes.

IMPACT STATEMENT

Our data provides novel evidence for a strong correlation between mother and offspring urinary metal patterns with a unique mother-to-offspring ratio for each metal. The study also provides new evidence for a strong positive association between early dysglycemia and urinary zinc, both in mothers and offspring. Weaker positive associations with urinary selenium and cadmium and negative associations with arsenic were also found. The low rate of preexisting diabetes in this population provides the unique advantage of minimizing the confounding effect of preexisting, diabetes related renal changes that would alter the relationship between dysglycemia and renal metal excretion.

Selenium intakes in the Irish adult population

Selenium (Se) is an essential trace element which has an important role as a constituent of seleno-proteins involved in various physiological processes. Previous research in Irish adults suggests that intakes of this important nutrient are suboptimal. The aim of the present study was to estimate the current intakes and major food sources of Se by Irish adults. Mean daily intakes (MDIs) of Se were calculated using data from the National Adult Nutrition Survey which involved 1500 Irish adults aged 18–90 years. The Se content of foods and drinks consumed over a 4-d period was determined using data from the Irish Total Diet Study (TDS). Adequacy of Se intakes was assessed by calculating the proportion of the population with intakes below the adequate intake (AI) of 70 μg/d and lower reference nutrient intake of 40 μg/d (LRNI). The MDI of Se in the total population was 71⋅7 μg/d, with significantly higher intakes reported in men (80⋅2 μg/d) compared with women (63⋅4 μg/d, P < 0⋅01). Meat and meat products were the major contributing food group to Se intakes for both men (37 %) and women (31 %). Overall, 47 % of the population were not meeting the recommended AI, while 4 % of the total population were not meeting the LRNI. Although the average intake of Se is above the AI, a significant proportion of the population is not meeting this recommendation and continued monitoring of Se intakes is necessary, particularly by at-risk groups and also in the context of sustainability.

A comprehensive review on environmental transformation of selenium: recent advances and research perspectives

Selenium (Se) is an important micronutrient and essential trace element for both humans and animals, which exist in the environment ubiquitously. Selenium deficiency is an important issue worldwide, with various reported cases of its deficiency. Low selenium contents in some specific terrestrial environments have resulted in its deficiency in humans. However, high levels of selenium in the geochemical environment may have harmful influences and can cause a severe toxicity to living things. Due to its extremely narrow deficiency and toxicity limits, selenium is becoming a serious matter of discussion for the scientists who deals with selenium-related environmental and health issues. Based on available relevant literature, this review provides a comprehensive data about Se sources, levels, production and factors affecting selenium bioavailability/speciation in soil, characteristics of Se, biogeochemical cycling, deficiency and toxicity, and its environmental transformation to know the Se distribution in the environment. Further research should focus on thoroughly understanding the concentration, speciation, Se cycling in the environment and food chain to effectively utilize Se resources, remediate Se deficiency/toxicity, and evaluate the Se states and eco-effects on human health.

Comparative analysis of cardiovascular effects of selenium nanoparticles and sodium selenite in zebrafish embryos

Selenium acts as an important element in the prevention and treatment of cardiovascular diseases but their health-related effects have not been fully explored. As a novel attempt, zebrafish embryos were treated separately with SeNPs (5-25 μg/ml) and sodium selenite (5-25 μg/ml) starting at early blastula stage. Abnormalities were also observed in the morphology of the zebrafish embryos. The SeNPs-treated embryos exhibited concentration-dependent increased in mortality, pericardial edema, and cardiac arrhythmia. In contrast, sodium selenite showed no significant malformation effect in developing zebrafish embryos. The results of the present study conclude that the SeNPs were more toxic than sodium selenite. The results also suggest that lower concentrations of SeNPs and sodium selenite can be used as possible therapeutic agents for cardiovascular-related problems.

Selenium exposure in subjects living in areas with high selenium concentrated drinking water: results of a French integrated exposure assessment survey

BACKGROUND

Selenium is an essential element which can be toxic if ingested in excessive quantities. The main human exposure is food. In addition, intake may be boosted by consumption drinking water containing unusual high selenium concentration.

OBJECTIVE

We measured the individual selenium level of people exposed to selenium concentration in drinking water greater than the maximum recommended limit which is 10 μg/L.

METHODS

We carried out a prospective cohort study on 80 adults (40 exposed subjects i.e. living in the involved area and 40 non-exposed ones i.e. living elsewhere) in western France. We used three different approaches: (1) direct measurement of ingested selenium by the duplicate portion method, (2) dietary reconstitution with a food frequency questionnaire (FFQ) and (3) evaluation of the individual selenium status by measuring the selenium content in toenail clippings. Analyses were performed by inductively coupled plasma-mass spectrometry. The association between toenail selenium concentration and area of residence was analyzed using linear regression with repeated measurements.

RESULTS

We estimated selenium intake from FFQ at 64±14 μg/day for exposed subjects as opposed to 52±14 μg/day for the non-exposed ones. On the basis of 305 duplicate diet samples, average intake was estimated at 64±26 μg/day for exposed subjects. Area of residence (p=0.0030) and smoking (p=0.0054) were independently associated with toenail selenium concentration.

CONCLUSION

Whatever method used for estimating selenium intake, the selenium level in this studied area with high selenium concentrated drinking water is much lower than in seleniferous areas.

Selenium and preeclampsia: A global perspective

Preeclampsia is a complex multisystem disorder of pregnancy where oxidative stress plays an important aetiological role. The role of selenium in the synthesis of endogenous antioxidants is well documented, and a significant reduction in selenium has been reported in preeclamptic women. The objective of this study was to map global selenium status and preeclampsia incidence. This study identified peer reviewed journal articles reporting national preeclampsia incidence (%) and matched these with reported values of selenium intake and plasma/serum selenium concentrations (μg/L). Matched data were obtained for 45 regions, reporting 6456,570 births, spanning Europe, Asia, Australasia, Africa, North and South America. Increasing plasma selenium concentration was found to be correlated with a reduction in preeclampsia incidence (Pearson's r=-0.604, P<0.0001). Countries with a reported serum/plasma selenium level of ⩾95μg/L were considered selenium sufficient and a significant reduction in preeclampsia incidence for countries above this value (P=0.0007) was noted. Significant reductions in preeclampsia incidence were found to coincide with increases in plasma/serum selenium concentration in the New Zealand (P=0.0003) and Finland (0.0028) populations following Government intervention. This study supports the hypothesis that selenium supplementation may be beneficial in reducing oxidative stress in women at risk of preeclampsia.

The nutrition transition in the Republic of Ireland: trends in energy and nutrient supply from 1961 to 2007 using Food and Agriculture Organization food balance sheets

Over the course of the last 50 years the Republic of Ireland has gone from being one of the poorest countries in Europe to one of the richest; however, it is now experiencing increasing rates of obesity and non-communicable chronic disease. Although several national nutrition surveys have been carried out in Ireland since 1990, there is little information on the Irish diet before then. We analysed the FAO food balance sheets for Ireland from 1961 to 2007 in order to characterise the changes in energy and nutrient supply that took place during that period. Food balance sheets were downloaded from the FAOSTAT database and per capita supply of commodities was analysed using dietary analysis software. Energy from carbohydrate as a percentage of total energy fell from 55 % in 1961 to 46 % in 2007, whereas energy from fat increased from 29 % to 34 %; these values are well outside WHO recommendations for the prevention of chronic disease. Energy from alcohol as a percentage of total energy has doubled within the last 20 years. On a nutrient-density basis, vitamins and minerals met or exceeded WHO recommendations, apart from vitamin D, folate, Ca and Fe. Although there are methodological limitations associated with the use of food balance sheets, the present results demonstrate that the current imbalances in the Irish diet were already evident several decades ago. Because they are so long established, they will be difficult to reverse unless major public health nutrition interventions are implemented.

Food-chain selenium and human health: emphasis on intake

Following the publication of the landmark trial of Clark et al. in 1996 that appeared to show that Se could reduce the risk of cancer, awareness of the importance of Se to human health has markedly increased. As a result, there is now much more aggressive marketing of Se supplements and functional foods, even in situations where additional consumption of Se is inappropriate. The present review addresses how Se gets into the food chain, the wide variability in Se content of foods and the very different levels of intake between countries and regions. Though it is clear that there are adverse consequences for health of both deficient and excessive intake, health effects at intermediate levels of intake are less certain. Thus it is difficult to define optimal intake which depends on a large number of factors, such as which functions of Se are most relevant to a particular disease state, which species of Se is most prominent in the Se source, which health condition is being considered, the adequacy or otherwise of intake of other nutrients, the presence of additional stressors, and lastly whether the ability to make selenoproteins may be compromised. These complexities need to be understood, particularly by policy makers, in order to make informed judgments. Potential solutions for increasing Se intake, where required, include agronomic biofortification and genetic biofortification or, for individuals, increased intake of naturally Se-rich foods, functional foods or supplements. The difficulties of balancing the risks and benefits in relation to Se intake are highlighted.

Selenium status of Irish adults: evidence of insufficiency

BACKGROUND

Sub-optimal selenium status may have a role in the aetiology of various pathologies. Selenium status depends on adequate selenium in the diet. A relatively high proportion of Irish adults (17% men; 46% women) have an inadequate dietary intake.

AIM

A study was designed to examine the selenium status of healthy Irish adults.

METHODS

Ninety-one healthy Irish adults, aged 18-67 years, were recruited from the Cork City area. A fasting blood sample was collected from each subject and each was assayed for serum selenium an index of serum selenium.

RESULTS

Mean (+/- SD) serum selenium concentration in healthy Irish adults was 76 (+/- 21)microg/l. There was no significant difference in values between males and females or between postmenopausal and premenopausal women or between the three main age categories.

CONCLUSION

Current serum selenium values of Irish adults would not appear to be sufficient to achieve optimal activity of glutathione peroxidase, which occurs at serum selenium concentration around 95microg/l. Sub-optimal selenium status may increase susceptibility to various chronic disorders.