Human metabolism and renal excretion of selenium compounds after oral ingestion of sodium selenite and selenized yeast dependent on the trimethylselenium ion (TMSe) status

Abstract

A human in vivo metabolism study was carried out to investigate the impact of the trimethylselenium ion (TMSe) status on metabolism and toxicokinetics of sodium selenite and selenized yeast. Nine healthy human volunteers were orally exposed to 200 µg selenium as sodium selenite and seven with selenized yeast (100 µg selenium). In each intervention group, three subjects belong to TMSe eliminators. Blood samples were withdrawn before and up to 6 h after administration. Urine samples were collected before and within 24 h after administration. Total selenium (Se) was quantified in blood plasma and urine and low molecular Se species in urine. Selenium concentration in plasma increased from 84.5 ± 13.2 µg Se/L before to 97.4 ± 13.2 µg Se/L 2-3 h after selenite supplementation and 89.5 ± 12.9 µg Se/L to 92.1 ± 13.9 µg Se/L after selenized yeast intake. The oral ingestion caused an additional Se elimination via urine of 16.9 ± 10.6 µg/24 h (TMSe elim.: 10.8 ± 6.9 µg/24 h; non-TMSe elim.: 20.0 ± 11.3 µg Se/24 h) after selenite exposure and 11.8 ± 4.1 µg/24 h (TMSe elim.: 10.8 ± 4.6 µg/24 h; non-TMSe elim.: 12.6 ± 4.2 µg Se/24 h) after selenized yeast exposure. Methyl-2-acetamido-2-deoxy-1-seleno-β-D-galactopyranoside (SeSug1) was the main metabolite in all urine samples, whereas TMSe was another main metabolite in TMSe eliminators' urine. After selenite exposure, a small amount of the dose (0.5 ± 0.2 %) was oxidized to selenate and rapidly excreted via urine. With the exception of selenite exposure in TMSe eliminators, the comparison of total Se and the sum of quantified Se species revealed a high renal portion of unidentified species. The study indicated a different metabolism of inorganic and organic Se compounds in human, but also crucial differences of Se metabolism in TMSe eliminators and non-TMSe eliminators.

Differing cytotoxicity and bioavailability of selenite, methylselenocysteine, selenomethionine, selenosugar 1 and trimethylselenonium ion and their underlying metabolic transformations in human cells

“…Additionally, isotope 78 Se + ( m/z 78) shifting with oxygen to 78 Se 16 O + ( m/z 94) as well as both Se isotopes on mass were monitored in the same gas mode to screen for interferences. As a commonly used internal standard, Ge was detected on m/z 72 .…”

“…Se isotopes on mass were monitored in the same gas mode to screen for interferences. As a commonly used internal standard, Ge was detected on m/z 72[12,13].…”

Exploring the urinary selenometabolome following a multi-phase selenite administration regimen in humans

“…4A) than selenosugar 3, which is in agreement with the previously published data. 12,14 The selenosugar 1 and selenosugar 3 levels were clearly higher in the postsupplementation phase compared to the pre-supplementation phase ( Fig. 4A and B).…”

“…12,13 Numerous studies explored the urinary excretion of selenium supplemented in various chemical forms, but based on different experimental designs employing single dosage administration. 12,[14][15][16] The aim of the present study is to investigate the urinary excretion of selenium metabolites in several volunteers following a regimen of a gradually increasing dosage of selenium supplementation to gain more insight into the human metabolism of selenium.…”

The Association between the Urinary Excretion of Trimethylselenonium and Trimethylsulfonium in Humans

“…This enzyme produces a variety of products including the selenium analogue of TMS, the trimethylselenonium ion (TMSe), and possesses several key physiological and toxicological functions [3,4]. Several European studies have consistently reported considerable inter-individual variability (20–40 fold) in the human metabolism to TMSe, splitting the study populations into so-called “TMSe producers” and “TMSe non-producers” with a ratio of about 1:4 [5–7]. …”