Dietary selenium: why do we need it and how much is enough?

Arthur, J. R.; Brown, K.M.; Fairweather-Tait, S. J.; Crews, Helen M.

doi:10.1108/00346659710180343

Cited by 15 publications

(10 citation statements)

References 12 publications

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“…Under physiological conditions the Se in selenocysteine is almost fully ionized, and consequently it is an extremely efficient biological catalyst [1]. It has been suggested that up to 100 selenoproteins may exist in mammalian systems [2], and up to 30 have been identified by (&Se labelling in vivo [3].…”

Section: Introductionmentioning

confidence: 99%

“…These include four glutathione peroxidase enzymes, which represent a major class of functionally important selenoproteins. The Se peroxidases are genetically, structurally and kinetically different, and yet have both common and individual functions [1]. Classical glutathione peroxidase (GPi1), so called because it was the first to be discovered, is present in the cell cytosol, where it functions as an antioxidant by directly reducing H # O # and lipid hydroperoxides [5].…”

Section: Introductionmentioning

confidence: 99%

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Effects of organic and inorganic selenium supplementation on selenoenzyme activity in blood lymphoctyes, granulocytes, platelets and erythrocytes

Brown¹,

Pickard²,

Nicol³

et al. 2000

Clinical Science

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The blood selenium (Se) concentration in the U.K. population has declined by approx. 50% between 1974 and 1991, reflecting a large decrease in dietary Se supply, with intakes only half the reference nutrient intake of 1 microg/kg body weight. Tissue levels of Se are readily influenced by dietary intake. Therefore selenoprotein activity may be sub-optimal due to low Se status, and thus compromise normal cell function. To examine the effects of changing Se intake on selenoproteins, we have determined the relative effectiveness of organic selenomethionine and inorganic sodium selenite (50 microg of Se daily for 28 days) in modulating glutathione peroxidase activities in blood cells from 45 healthy men and women, from a U.K. population. Transient and acute changes in lymphocyte, granulocyte and platelet phospholipid-hydroperoxide glutathione peroxidase (GPx4) activity occurred by day 7 or 14 of sodium selenite treatment and by day 7 in lymphocytes from selenomethionine-treated subjects compared with controls taking a placebo. In contrast, GPx4 activity in granulocytes and platelets in the selenomethionine group increased gradually over the 28 days. Cytosolic glutathione peroxidase (GPx1) activity in these blood cells from both treatment groups increased gradually over the 28 days. For each cellular selenoenzyme activity a significant inter-individual difference (P<0.001) in the extent of the response to Se supplementation was observed, but this was not related to blood Se concentrations either before or after treatments. Significant inverse correlations were evident between baseline enzyme activities and percentage change in activity after 28 days of supplementation [e.g. lymphocyte GPx4, r=-0.695 (P<0.001)], indicating that pre-treatment activity may be sub-optimal as a result of poor Se status. The different and contrasting effects that Se supplementation had on blood selenoenzyme activities may be indicative of a difference in metabolic need for Se regulated at the level of Se-dependent cell function.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of organic and inorganic selenium supplementation on selenoenzyme activity in blood lymphoctyes, granulocytes, platelets and erythrocytes

Brown¹,

Pickard²,

Nicol³

et al. 2000

Clinical Science

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“…These enzymes provide mechanisms by which intracellular biological structures are protected against potentially damaging effects of peroxide free radical-mediated attacks. 1 There is also increasing evidence that Se plays an important protective role both in the human immune system and in the prevention and suppression of a number of specific disorders such as carcinomas, cardiovascular diseases, cystic fibrosis and low fertility. [2][3][4] Despite its dietary significance, Se is an element for which the concentration range from trace element requirement to toxicity is relatively narrow.…”

Section: Introductionmentioning

confidence: 99%

Evidence of low selenium concentrations in UK bread‐making wheat grain

et al. 2002

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The selenium concentration of representative bread-making wheat (Triticum aestivum L) samples was measured in national grain surveys collected in 1982 (n (number of samples) = 180), 1992 (n = 187) and 1998 (n = 85) from major wheat-growing regions around the UK. The means and distributions of selenium concentrations over the three years were similar, with mean grain concentrations of 0.025, 0.033 and 0.025 mg kg À1 dry weight respectively and inter-quartile ranges varying from 0.015 mg kg À1 in 1982 to 0.019 mg kg À1 in 1992 samples. No long-term changes in the distribution of wheat selenium concentrations were found over the 17 year period. Geographical mapping of the concentrations identified an area of eastern England as having high grain concentrations compared with other UK regions. There were no significant correlations between grain selenium and grain sulphur concentrations for the national survey samples. However, at an individual field experimental site, increasing the rate of sulphur addition was found to decrease grain selenium concentration significantly. The daily UK dietary contribution of selenium from wheat-based products was estimated and the daily intake was calculated to be 6.4 mg selenium, around one-tenth of the UK recommended intake values for men and women.

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“…These include four glutathione peroxidase enzymes (classical GPx1, gastrointestinal GPx2, plasma GPx3, phospholipid hydroperoxide GPx4) which represent a major class of functionally important selenoproteins. The Se peroxidases are genetically, structurally and kinetically different yet have both common and individual functions 3 .…”

Section: Selenoproteinsmentioning

confidence: 99%

Selenium, selenoproteins and human health: a review

Brown¹,

Arthur²

2001

Public Health Nutr.

804

380

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Selenium is of fundamental importance to human health. It is an essential component of several major metabolic pathways, including thyroid hormone metabolism, antioxidant defence systems, and immune function. The decline in blood selenium concentration in the UK and other European Union countries has therefore several potential public health implications, particularly in relation to the chronic disease prevalence of the Western world such as cancer and cardiovascular disease. Ten years have elapsed since recommended dietary intakes of selenium were introduced on the basis of blood glutathione peroxidase activity. Since then 30 new selenoproteins have been identified, of which 15 have been purified to allow characterisation of their biological function. The long term health implications in relation to declining selenium intakes have not yet been thoroughly examined, yet the implicit importance of selenium to human health is recognised universally. Selenium is incorporated as selenocysteine at the active site of a wide range of selenoproteins. The four glutathione peroxidase enzymes (classical GPx1, gastrointestinal GPx2, plasma GPx3, phospholipid hydroperoxide GPx4)) which represent a major class of functionally important selenoproteins, were the first to be characterised. Thioredoxin reductase (TR) is a recently identified seleno-cysteine containing enzyme which catalyzes the NADPH dependent reduction of thioredoxin and therefore plays a regulatory role in its metabolic activity.

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Dietary selenium: why do we need it and how much is enough?

Cited by 15 publications

References 12 publications

Effects of organic and inorganic selenium supplementation on selenoenzyme activity in blood lymphoctyes, granulocytes, platelets and erythrocytes

Effects of organic and inorganic selenium supplementation on selenoenzyme activity in blood lymphoctyes, granulocytes, platelets and erythrocytes

Evidence of low selenium concentrations in UK bread‐making wheat grain

Selenium, selenoproteins and human health: a review

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