The metabolism of [⁷⁵Se]selenomethionine in four women

Abstract

I. The long-term fate of an oral dose of [75Se]selenomethionine was studied in four women. 2 . Urinary and faecal excretion, respiratory losses and whole-body retention of 75Se were measured, and also 75Se turnover in whole body, plasma and erythrocytes during a period of 33-44 weeks.3. Intestinal absorption of [75Se]selenomethionhe by the four subjects was 95'5-97'3 % of the administered dose.4. Urinary excretion accounted for 6-9% of absorbed 75Se in the first z weeks. No radioactivity was detected in expired air.5 . After the initial 8 weeks during which radioactivity decreased more rapidly, wholebody retention of 75Se decreased exponentially with a half-time of 207-290 d.6 . Plasma 75Se concentration reached a maximum level 3-4 h after the dose. Transient initial uptake of 75Se in erythrocytes during the first hour was followed by a gradual increase to a maximum concentration at 8-12 weeks.7. These results are compared with the results of an earlier study of the metabolism of [75Se]selenite in two of the same women. '%e from [76Se]selenomethionine was found to be more completely absorbed, had a greater retention and smaller endogenous urinary and faecal losses than W e from [75Se]selenite, and these differences persisted throughout the experimental period. These findings differed from those obtained in rats in which, after an initial period, 75Se from selenite was metabolized similarly to that from selenomethionine.The unusually low concentration of selenium in the blood of New Zealand residents has stimulated interest in its possible role in human nutrition (Griffiths, 1973; Griffiths & Thomson, 1974; Watkinson, 1974;Robinson, 1975). Although it is not established that the intake of Se should be increased, information is required about the metabolism of Se in man. The fate of an oral dose of [75Se]selenite was studied in three women (Thomson & Stewart, 1974) and in the present study the fate of an oral dose of [75Se]selenomethionine has been studied in four women, of whom two were subjects in the previous experiment. E X P E R I M E N T A L ProcedureThe subjects G, R, C and T were four women aged 34, 26, 22 and 23 years respectively, with a mean height of 1-63 m and a mean weight of 60 kg. Subjects G and R had also participated in the previous study (Thomson & Stewart, 1974

Bioavailability of selenium from fish, yeast and selenate: a comparative study in humans using stable isotopes

“…The absorption of selenium from fish compared well with selenate absorption and is also comparable with foods from plant origin, reported to be 79% , 80% (Mutanen, 1986), 81% from garlic and 83% from wheat . Studies investigating the absorption of selenomethionine have shown similar results with reported absorption values of 96% (Griffiths et al, 1976), 90% , 75% and 95% (Dreosti, 1986). There have been a few reports that selenium absorption from fish is lower than from other foods Robinson & Thomson, 1983;Mutanen, 1986).…”

Absorption and initial metabolism of 75Se-l-selenomethionine: a kinetic model based on dynamic scintigraphic data

“…Currently, our understanding of Se absorption, whole-body retention and excretion is based on whole-body counting (5) or balance and tracer studies (6)(7)(8) . Data from previous studies (13)(14)(15) indicate a fundamental complexity of Se metabolism that can be explained by several factors.…”

“…Estimates of Se absorption, whole-body retention and excretion have been made predominantly on whole-body counting (5) or the recovery of ingested tracers in the blood, urine and faeces (6) . Compartmental analyses of kinetic data from tracer studies have also been used to create a more integrated picture of whole-body Se utilisation in humans (7,8) .…”

Selenium in Soil-Crop-Animal System: A Holistic Perspective to Manage Animal and Human Health

“…The reduced selenium species undergo further transformations to the forms needed for the biosynthesis of the ultimate form, selenoenzymes. In studies with New Zealand women, the selenium absorption from selenite reached 44-70%, compared to 96% from Se-Met [70,71], while [72] observed 84% selenium absorption from selenite and 98% from SeMet. In addition to selenodicystine and selenodiglutathione, the Se-exchangeable pool contains numerous other selenium species, including endogenously synthesized selenoproteins (e.g.…”