Selenium status of healthy immigrant Parisian preschool children

Selenium status and associated factors in a British National Diet and Nutrition Survey: young people aged 4-18 y

OBJECTIVE

Assessment of selenium status to provide normative reference values, and investigation of associated socio-demographic factors, in a national sample of British young people aged 4-18 y.

SETTING

National Diet and Nutrition Survey-a nationwide cross-sectional sample of young people aged 4-18 y living in mainland Britain in 1997.

METHODS

Selenium status was measured, mainly in fasting blood samples, by plasma selenium concentration in 1127 participants, by red blood cell (RBC) selenium concentration in 1112, and by whole-blood glutathione peroxidase (GPx) activity in 658.

RESULTS

No evidence of severe selenium deficiency or toxicity was observed. Plasma selenium concentration was directly correlated with RBC selenium concentration, and both were associated directly, although less strongly, with GPx activity. Plasma and RBC selenium concentrations increased significantly with age, with RBC concentrations significantly higher in older girls than boys. Region of domicile exhibited a significant relationship. Associations also occurred with parental occupational social class, selenium concentrations being higher in more socially advantaged children. Black and Indian children had considerably higher concentrations than Caucasian children. Concentrations, especially of plasma selenium, were significantly lower in children either (or both) of whose parents were smokers, although, unexpectedly, there was no evidence that children who themselves smoked had lower levels.

CONCLUSIONS

The observed associations between selenium status indices and age, gender, social class, parental smoking and ethnic group indicate a complex network of biological factors which determine selenium concentrations in blood components, and which thus need to be controlled for when using these indices to assess selenium status in young people.

SPONSORSHIP

The survey was commissioned jointly by the Department of Health and the Ministry of Agriculture, Fisheries and Food, whose responsibility has since been transferred to the Food Standards Agency. Support for the further analysis presented in this paper was provided by the Department of Health.

Age-related Reference Values for Serum Selenium Concentrations in Infants and Children

Background: Children are at particular risk for selenium deficiency, which has potentially serious medical implications. Reliable age-specific reference values for serum selenium concentrations in children are sparse, but are essential for the identification of selenium deficiency and decisions regarding selenium supplementation.

Methods: Using electrothermal atomic absorption spectrometry, we analyzed serum selenium concentrations from 1010 apparently healthy children (age range, 1 day to 18 years) and from 60 patients on a protein-restricted diet because of inborn errors of metabolism. Reference intervals were defined according to recommended guidelines.

Results: Medians for serum selenium concentrations showed a statistically significant age dependency: a decrease from the age <1 month (0.64 μmol/L) to 4 months (0.44 μmol/L); an increase to 0.62 μmol/L in the 4–12 months age group; constant values in children between 1 and 5 years of age (0.90 μmol/L); and an additional slight increase to reach a plateau between 5 and 18 years (0.99 μmol/L). Of 43 children older than 1 year and on a protein-restricted diet, 87% showed serum selenium concentrations below the 2.5 percentile.

Conclusions: Because of nutritional changes, serum selenium concentrations are significantly higher in older children than in infants under 1 year of age. The application of age-adjusted reference values may provide more specific criteria for selenium supplementation. Long-term protein restriction in children is reflected by a failure to achieve higher serum selenium concentrations with increasing age.

Serum selenium concentration in a representative sample of the Canarian population

The concentration of serum selenium in 395 individuals (187 males + 218 females) living in the Canary Islands, Spain was determined by hydride generation atomic absorption spectrometry. The mean selenium concentration was 74.7 +/- 25.2 microg/l ranging between 7.86 and 182.3 microg/l. Twenty-two adults (7.2% of the total) had serum selenium concentrations under 45 microg/l. It is widely accepted that below this selenium serum concentration (45 microg/l) there is an increased risk of cardiovascular disease and cancer. Our results fall within data recently published in other Spanish and European regions and are much lower than data observed in USA or seleniferous regions. The estimated Se intakes of our population were lower than the Recommended Dietary Allowances for American people. Individuals from Lanzarote had a mean Se concentration significantly higher than individuals from the other islands. This could be attributed to differences in Se content of soil and/or differences in dietary habits of the populations. Serum selenium concentration did not vary with the sex of the subjects. Individuals younger than 14 years old had a serum selenium concentration significantly lower than the rest of the individuals. No relationship with socio-economic status, educational level, smoking habits, physical exercise or beer consumption was found. However, individuals who consume wine more than three times a week showed higher selenium concentrations than individuals with lower consumption. Also, individuals with consumption above seven units of spirit drinks a week had the highest mean selenium concentration.

Serum selenium levels in healthy Slovak children and adolescents

Blood serum selenium levels were measured in 891 healthy children and adolescents (aged 11-18 yr, 450 girls and 441 boys) residing in both rural and urban areas from eight regions of Slovakia. Subjects were divided into four age groups (11-12 y, 13-14 y, 15-16 y, and 17-18 y). Serum selenium concentration was determined by the electrothermal atomic absorption spectrometric method. The mean (+/-SD) serum selenium concentrations were 0.750+/-0.255 micromol/L in girls and 0.773+/-0.235 micromol/L in boys. A large proportion of the individuals (25.7% in girls, 18.1% in boys) exhibited serum selenium levels under 0.57 micromol/L (45 microg/L). An increasing trend of the serum selenium values with age has been observed in both boys (p < 0.01) and girls (p < 0.05). Boys had higher serum selenium levels in the all age groups but the differences were not statistically significant.

Reference values for the trace elements copper, manganese, selenium, and zinc in the serum/plasma of children, adolescents, and adults

Up to now few plasma or serum reference or serum reference values have been available for the assessment of the essential trace element supply status in different age groups covering the whole range of life range. In the present investigation, the concentrations of copper, manganese, selenium, and zinc were determined in the serum of 137 healthy children and in the plasma of 68 blood-donors. The age distribution within these groups ranged from 1 month to 18 years and from 22 to 75 years. The determinations were carried out directly by means of electrothermal atomic absorption spectrophotometry with Zeeman background compensation. The adult plasma reference values (mean +/- 2 SD) were 1.65 +/- 8.6 mumol/1 for copper, 14.3 +/- 11.4 nmol/1 for manganese, 0.80 +/- 0.36 mumol/1 for selenium, and 16.6 +/- mumol/1 for zinc. No correlation between concentration of elements and sex could be established. In the child and adolescent group, the manganese levels exhibited an age-dependent linear decrease (54% of the starting value, slope 0.92, r = 0.4, p < 0.001), the copper and the selenium concentrations, respectively, exhibited an exponential increase (107%, r = 0.59 and 174%, r = 0.61), with the highest value in the age group of 6 to 10 years. Reference ranges are established for 9 different age groups. The results reflect the known physiological data on the trace element content in the tissue of children and their diet. The present study is an important pre-requisite for diagnosis and therapy of trace element deficiencies in all age groups.

Selenium and glutathione peroxidase activity in Hungarian children

Selenium (Se) in plasma, whole blood and erythrocytes as well as glutathione peroxidase (GSH-Px) activity in plasma and erythrocytes were investigated in 161 healthy Hungarian children aged 1-15 years. Se was determined by AAS with hydride generation. The estimation of GSH-Px activity was performed in plasma with tertbutyl-hydroperoxide (t-BOOH) and in erythrocytes with hydrogen peroxide (H2O2) as acceptor substrates. The Se content in plasma (0.63 +/- 0.12 mumol/L), whole blood (0.81 +/- 0.14 mumol/L) and erythrocytes (1.14 +/- 0.26 mumol/L, the GSH-Px activity in plasma (87 +/- 19 U/L) and erythrocytes (5.93 +/- 1.04 U/gHb) was low in Hungarian children in comparison to values for children from other European countries. Samples from a rural area in southeast Hungary showed even lower Se content than samples from an industrial city in the northwest or from the capital. The Se in plasma and whole blood as well as GSH-Px activity in the plasma exhibited a clear age dependency. There was a good correlation between plasma Se and GSH-Px activity in all children (r = 0.633, p < 0.001). In addition, in children from the northwestern city and from the capital a correlation was found between Se content and GSH-Px activity of erythrocytes (r = 0.625, p < 0.001). There is no indication that the high mortality in young Hungarian adults from cardiovascular diseases is mainly caused by a low Se supply because there are no corresponding findings in the surrounding countries of southeastern or central eastern Europe with similar low Se states.

Actual daily dietary intake of selenium in Belgium, using duplicate portion sampling

The dietary selenium (Se) intake in Belgium has been re-evaluated. Duplicate meal collection, wet acid destruction and flow injection hydride generation atomic absorption spectrometry were used as techniques. The daily intake ranged from 28.4 micrograms (Liège, Walloon part of the country) to 61.1 micrograms (Vilvoorde, central part of the country). Compared with intakes recently published for other countries, the actual Belgian value corresponds to intermediate ranges of Se intake.