Human Selenium Status Research Articles

The effect of an enriched selenium-76 supplement on dietary monitors and glutathione peroxidase activity

The objective of this study was to determine if a stable enriched tracer of Se-76 could be used to establish the delay time between a dietary intake of selenium and its appearance in various matrices. Selenium, an essential trace element, has been investigated at the Missouri University Research Reactor (MURR) for several years. Several matrices have been studied to determine selenium status in humans; these include fingernails, toenails, blood, hair, and urine. A cohort of five women and seven men was utilized for this study. Each subject ingested selenium supplements which were enriched in Se-76 (96.48%). Fingernails, toenails, whole blood, and blood sera were collected as biochemical indicators. Selenium concentrations and glutathione peroxidase activities were determined in blood sera and whole blood to monitor the effect of the selenium supplement in these matrices. Selenium concentrations were determined in fingernails and toenails prior to supplementation and for several months afterward to determine the delay time for the appearance of selenium. The effects of the selenium supplement on the selenium concentrations of the fingernails, toenails, whole blood, and blood sera and the effect of the supplement on glutathione peroxidase activity will be reported.

Direct determination of selenium in serum by electrothermal atomic absorption spectrometry using automated ultrasonic slurry sampling

Selenium concentration in body fluids is a good index to establish human selenium status. This work discusses the determination of selenium in serum by ETAAS using longitudinal Zeeman-effect background correction and combining the use of automated slurry sampling. The standard reference materials bovine serum (NIST, SRM 1598) and second-generation biological freeze-dried human serum are analyzed to verify the accuracy and precision of this technique. The direct method proposed in this study is used for the determination of selenium in human serum collected from healthy people of 19–25 years. The average accuracy values of certified reference serum samples and the recovery values of spiked samples indicate this method to be an efficient and rapid technique for determining selenium in biological samples.

Selenium Determination in Serum by Graphite Furnace Atomic Absorption Spectrometry

AbstractSelenium concentration in serum has been proposed as the most valuable indicator of human selenium status. In this work, the concentration of selenium in serum is measured by GFAAS using longitudinal Zeeman‐effect background correction, a highly sensitive technique that can be used to determine selenium at sub‐ppb level. Standard reference materials are analyzed to verify the accuracy and precision of this technique. The direct method proposed in this study is used for the determination of selenium in human serum collected from healthy people of 19–25 years and women of 21–34 years in the First trimester of pregnancy. The method developed in this study, which can quickly and accurately measure serum selenium, is suitable for applications in clinical diagnosis or biological monitoring.

Serum Selenium in Institutionalized Elderly Subjects and Relation to Other Nutritional Markers

Nowadays, there is growing interest in the possible relationship between selenium metabolism and the aging process (1). Epidemiological studies show that selenium may have a preventive role in some degenerative diseases such as hepatic cirrhosis, cardiovascular diseases, and some types of cancer (2)(3). However, information on the influence of selenium on aging is contradictory, apart from the fact that the process is not yet well understood. We determined the serum concentrations of Se in 93 institutionalized elderly people in Granada (Spain) as a short-term indicator of human selenium status and its correlation with nutrient intake. In addition, taking into account the role of Se in oxidation, in metabolic changes in plasma lipids, and as a component of glutathione peroxidase, we examined other biochemical markers, e.g., total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglycerides. We likewise studied leukocyte numbers in blood, as an indicator of risk of disease through infection, and established their correlation with serum Se concentrations. To quantify serum selenium, we used the hydride generation atomic absorption spectrometry technique previously optimized (4). Daily dietary intake was determined by the 7-day weighed food record, including a day off (5). Unfortunately, …

Effects of supplementation of fertilizers on human selenium status in Finland.

The Se concentration of foods can be increased by supplementing fertilizers with soluble Se compounds. In Finland the availability of soil Se for plants is poor owing to the relatively low Se concentration, low pH and high iron content of the soil. Since 1984 multimineral fertilizers have been supplemented with Se (16 mg kg-1 to fertilizers for grain production and 6 mg kg-1 to those for fodder production) in the form of sodium selenate. Within two years a three-fold increase of mean Se intake was observed. The supplementation affected the Se content of all major food groups with the exception of fish. The concomitant human serum Se concentration increased by 70%. In 1990 the amount of Se that was supplemented was reduced to 6 mg kg-1 for all fertilizers. This reduced the mean Se intake by 30% and the serum Se concentration decreased by 25% from the highest levels observed in 1989. Plants take up part of the supplemented selenate and transform it into organic Se compounds, mainly selenomethionine. This affects human nutrition by increasing the Se content of foods of both animal and vegetable origin. According to data obtained in Finland, supplementation of fertilizers with Se is a safe and effective means of increasing the Se intake of both animals and humans that is feasible in countries with relatively uniform geochemical conditions. This kind of intervention requires careful monitoring of the effects on both animal and human nutrition and the environment.

Toenail selenium as an indicator of selenium intake among middle-aged men in an area with low soil selenium

Toenail selenium concentration has been proposed as a long-term (6-12 mo) indicator of human selenium status. This study investigated the association between toenail selenium concentration and selenium intake and other dietary factors among 166 urban men aged 55-69 y. The dietary information was collected by food records covering a 6-mo period. Toenail clippings were collected by mail 9-10 mo after food recording. The mean selenium intake from food was 42.5 micrograms/d and the dietary intake was equal to that of users and nonusers of selenium supplements. The mean toenail selenium concentration was 0.47 mg/kg. The mean selenium intake from supplements was 29.7 micrograms/d among supplement users. In the analysis of covariance the best predictors of toenail selenium concentration were selenium intake from supplements and food, and among supplement users dietary beta-carotene also.

Indexes of selenium status in human populations

This paper considers the factors that affect the bioavailability of selenium to human populations and describes briefly the consequences of an inadequate dietary intake of selenium in the Peoples' Republic of China and in Zaire. A review of human blood selenium concentrations worldwide reveals very large differences in the apparent dietary status of individuals in different areas. The question is raised as to whether blood selenium measurement is a reliable index of actual selenium status in terms of bioavailability and function of the element. It is concluded that the preferred indexes of human selenium status are blood, or plasma and/or serum, concentrations of the element and the level of activity of the selenium-dependent enzyme glutathione peroxidase in erythrocytes or in plasma. Several important caveats to this conclusion are mentioned and other means of assessing selenium status are also considered.

Automated measurement of two indicators of human selenium status, and applicability to population studies

We developed an automated system consisting of a centrifugal analyzer and an atomic absorption spectrophotometer with Zeeman background correction to produce a profile of the concentrations of selenium and the selenium-dependent enzyme glutathione peroxidase (EC 1.11.1.9) in serum and whole blood, for use in epidemiological surveys in Northern Ireland. No pretreatment of samples other than dilution is required, and at least 35 subjects can be screened within 24 h of venesection. For selenium in serum the between-run CV was 5.7% and 4.4% within run. For selenium in whole blood the CV was 5.9% between runs, 5.7% within run. The within-run CV for glutathione peroxidase was 0.92% for serum, 1.18% for blood; the between-run CV was 8.3% for serum. To illustrate the use of the system, we present the profile of selenium and glutathione peroxidase in serum and whole blood from 100 adults 25 to 64 years old.

Single-void urine selenium level expressed in terms of creatinine content as an effective and convenient indicator of human selenium status.

Single-void urine selenium level expressed in terms of creatinine content as an effective and convenient indicator of human selenium status.