Meat as a component of a healthy diet - are there any risks or benefits if meat is avoided in the diet?

In this review a brief summary will be given of the food sources, absorptive mechanism and subsequent metabolism of the nine mineral and trace element identified as being nutritionally important (calcium, chromium, cuivre, iodine, iron, magnesium, manganese, selenium, zinc)

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Bioavailability of Minerals and Trace Elements

Human selenium supplementation as assessed by changes in blood selenium concentration and glutathione peroxidase activity

Selenium in poultry nutrition.

Background: Selenium is an essential trace element that also elicits toxic effects at modest intakes. Investigations of selenium metabolites in urine can help our understanding of the transformations taking place in the body that produce these beneficial and detrimental effects. There is, however, considerable discord in the scientific literature regarding the selenium metabolites thought to play important roles in these biotransformation processes.

Approach: We critically assessed the published reports on selenium urinary metabolites, from the first report in 1969 to the present, in terms of the rigor of the data on which structures have been proposed.

Content: We present and discuss data from ∼60 publications reporting a total of 16 identified selenium metabolites in urine of humans or rats, a good model for human selenium metabolism. We assessed the analytical methods used and the validity of the ensuing structural assignments.

Summary: Many of the studies of selenium metabolites in urine appear to have assigned incorrect structures to the compounds. The long-held view that trimethylselenonium ion is a major human urinary metabolite appears unjustified. On the other hand, recent work describing selenosugars as major urinary metabolites looks sound and provides a firm basis for future studies.

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Selenium Metabolites in Urine: A Critical Overview of Past Work and Current Status

Twenty young Chinese men (ages 18–40 with a mean age of 29 years) living in a selenium deficient area of China (Dechang county. Sichuan province) were selected, divided into two groups, and provided with 200 μg selenium daily for 1 year as either selenate or selenomethionine (Semet). Blood and 24-hour urine samples were collected initially, after 1 month of supplementation and subsequently at bimonthly intervals. Selenium increased in both plasma and erythrocytes at a significantly faster rate in deficient men taking Semet than in those taking selenate. Glutathione peroxidase (GSH-Px) activity increased in both plasma and erythrocytes up to 4 months where a plateau was reached, but there were no differences in this activity between these two supplemental groups. The percentage of selenium associated with GSH-Px was significantly lower in plasma and erythrocytes in men taking. Semet than in those taking selenate. Gel filtration chromatography revealed two selenium-containing peaks in plasma of men taking Semet but mostly one in plasma from men taking selenate. Urinary excretion of selenium gradually increased throughout this study, but there were no differences in the excretion of total selenium or trimethylselenium (TMSe) between the two treatment groups. The TMSe content ranged between 1%–2.5% of total selenium in both groups.

Y. Xia

Papers

Metabolism of selenate and selenomethionine by a selenium-deficient population of men in China