A randomized trial of selenium supplementation and risk of type-2 diabetes, as assessed by plasma adiponectin

Background: Evidence that selenium affects the risk of type-2 diabetes is conflicting, with observational studies and a few randomized trials showing both lower and higher risk linked to the level of selenium intake and status. We investigated the effect of selenium supplementation on the risk of type-2 diabetes in a population of relatively low selenium status as part of the UK PRECISE (PREvention of Cancer by Intervention with SElenium) pilot study. Plasma adiponectin concentration, a recognised independent predictor of type-2 diabetes risk and known to be correlated with circulating selenoprotein P, was the biomarker chosen. Methods: In a randomized, double-blind, placebo-controlled trial, five hundred and one elderly volunteers were randomly assigned to a six-month intervention with 100, 200 or 300 μg selenium/d as high-selenium or placebo yeast. Adiponectin concentration was measured by ELISA at baseline and after six months of treatment in 473 participants with one or both plasma samples available. Results: Mean (SD) plasma selenium concentration was 88.5 ng/g (19.1) at baseline and increased significantly in the selenium-treatment groups. In baseline cross-sectional analyses, the fully adjusted geometric mean of plasma adiponectin was 14% lower (95% CI, 0-27%) in the highest than in the lowest quartile of plasma selenium (P for linear trend = 0.04). In analyses across randomized groups, however, selenium supplementation had no effect on adiponectin levels after six months of treatment (P = 0.96). Conclusions: These findings are reassuring as they did not show a diabetogenic effect of a six-month supplementation with selenium in this sample of elderly individuals of relatively low selenium status

Effect of dietary organic and inorganic selenium supplementation on chemical, mineral and fatty acid composition of ostrich meat

This study evaluated the effect of dietary organic and inorganic selenium supplementation on chemical, mineral and fatty acid composition of ostrich meat. Forty ostriches were raised in two groups (OSe and IOSe, diets supplemented with an organic form and an inorganic form of selenium, respectively). The form of selenium had no influence on chemical composition of ostrich muscle. Although, there were no significant differences in total content of SFA, MUFA and PUFA, the content of LA and EPA was higher in the muscles of ostriches which were put on a diet supplemented with an organic form of selenium, what resulted in lower n-6/n-3 fatty acids ratio in OSe group (9.99) in comparison to IOSe group (11.70). The results of the study indicate that dietary organic selenium supplementation improves the quality of the ostrich meat as related to the health promoting properties (LA, EPA and selenium content) of meat

A note on the effectiveness of selenium supplementation of Irish-grown Allium crops.

peer-reviewedThis study is funded by the Department of Agriculture and Food through the Network and Team Building Initiative of the Food Institutional Research Measure (FIRM Reference Number 06/NITARFC6).Onions and other Allium crops contain high levels of dietary phenolics and, unlike many other crops, accumulate the beneficial mineral selenium. Selenium-enhanced Allium crops are of interest both from a public good perspective and as a market positioning strategy for growers. Field trials were carried out to i) identify onion and scallion varieties that contain high levels of health-promoting phenolic and flavonoid compounds as potential targets for selenium supplementation and ii) investigate selenium supplementation in the widely-grown commercial onion variety ‘Hyskin’ at different application rates of nitrogen fertilizer. Levels of selenium in onion bulbs were significantly increased from 0.5–5.9 μg/g dry weight (DW) to 40.6–70.0 μg/g DW.Department of Agriculture, Food and the Marin

Serum selenium concentrations and diabetes in U.S. adults : National Health and Nutrition Examination Survey (NHANES) 2003–2004

Background: Increasing evidence suggests that high selenium levels are associated with diabetes and other cardiometabolic risk factors. Objectives: We evaluated the association of serum selenium concentrations with fasting plasma glucose, glycosylated hemoglobin levels, and diabetes in the most recently available representative sample of the U.S. population. Methods: We used a cross-sectional analysis of 917 adults ≥ 40 years of age who had a fasting morning blood sample in the National Health and Nutrition Examination Survey 2003–2004. We evaluated the association of serum selenium, measured by inductively coupled plasma-dynamic reaction cell-mass spectrometry, and diabetes, defined as a self-report of current use of hypoglycemic agents or insulin or as fasting plasma glucose ≥ 126 mg/dL. Results: Mean serum selenium was 137.1 μg/L. The multivariable adjusted odds ratio [95% confidence interval (CI)] for diabetes comparing the highest quartile of serum selenium (≥ 147 μg/L) with the lowest (< 124 μg/L) was 7.64 (3.34–17.46). The corresponding average differences (95% CI) in fasting plasma glucose and glycosylated hemoglobin were 9.5 mg/dL (3.4–15.6 mg/dL) and 0.30% (0.14–0.46%), respectively. In spline regression models, the prevalence of diabetes as well as glucose and glycosylated hemoglobin levels increased with increasing selenium concentrations up to 160 μg/L. Conclusions: In U.S. adults, high serum selenium concentrations were associated with higher prevalence of diabetes and higher fasting plasma glucose and glycosylated hemoglobin levels. Given high selenium intake in the U.S. population, further research is needed to determine the role of excess selenium levels in the development or the progression of diabetes

Novel sulfur and selenium containing bis-α-amino acids from 4-hydroxyproline

The synthesis of new substituted prolines carrying at C-4 a second α-amino acid residue is reported. The amino acid, l-cysteine or l-selenocysteine, is linked to the proline ring through the sulfur or the selenium atom, respectively. The products were prepared with different stereochemistry at C-4, in few and clean high-yielding steps, with suitable protections for solid phase applications. The introduction of both sulfur and selenium atoms at C-4 of the proline ring seems to enhance significantly the cis geometry at the prolyl amide bond

Biomarkers of selenium status in dogs

Background: Inadequate dietary selenium (Se) intake in humans and animals can lead to long term health problems, such as cancer. In view of the owner's desire for healthy longevity of companion animals, the impact of dietary Se provision on long term health effects warrants investigation. Little is currently known regards biomarkers, and rate of change of such biomarkers in relation to dietary selenium intake in dogs. In this study, selected biomarkers were assessed for their suitability to detect changes in dietary Se in adult dogs within eight weeks. Results: Twenty-four dogs were fed a semi-purified diet with an adequate amount of Se (46.1 mu g/MJ) over an 8 week period. They were then divided into two groups. The first group remained on the adequate Se diet, the second were offered a semi-purified diet with a low Se concentration (6.5 mu g/MJ; 31 % of the FEDIAF minimum) for 8 weeks. Weekly urine and blood was collected and hair growth measurements were performed. The urinary Se to creatinine ratio and serum Se concentration were significantly lower in dogs consuming the low Se diet from week 1 onwards, by 84 % (adequate 25.3, low 4.1) and 7 % (adequate 257 mu g/L, low 238 mu g/L) respectively. Serum and whole blood glutathione peroxidase were also significantly lower in dogs consuming the low Se diet from weeks 6 and 8 respectively. None of the other biomarkers (mRNA expression and serum copper, creatine kinase, triiodothyronine: thyroxine ratio and hair growth) responded significantly to the low Se diet over the 8 week period. Conclusions: This study demonstrated that urinary Se to creatinine ratio, serum Se and serum and whole blood glutathione peroxidase can be used as biomarkers of selenium status in dogs. Urinary Se to creatinine ratio and serum Se concentrations responded faster to decreased dietary Se than the other parameters. This makes these biomarkers candidates for early screening of long term effects of dietary Se provision on canine health

Selenium supplementation of lactating dairy cows: effects on milk production and total selenium content and speciation in blood, milk and cheese

Forty-multiparous Holstein cows were used in a 16-wk continuous design study to determine the effects of either selenium (Se) source, selenized yeast (SY) (derived from a specific strain of Saccharomyces cerevisiae CNCM I-3060 Sel-Plex®) or sodium selenite (SS), or inclusion rate of SY on Se concentration and speciation in blood, milk and cheese. Cows received ad libitum a TMR with 1:1 forage:concentrate ratio on a dry matter (DM) basis. There were four diets (T1-T4) which differed only in either source or dose of Se additive. Estimated total dietary Se for T1 (no supplement), T2 (SS), T3 (SY) and T4 (SY) was 0.16, 0.30, 0.30 and 0.45 mg/kg DM, respectively. Blood and milk samples were taken at 28 day intervals and at each time point there were positive linear effects of SY on Se concentration in blood and milk. At day 112 blood and milk Se values for T1-T4 were 177, 208, 248, 279 ± 6.6 and 24, 38, 57, 72 ± 3.7 ng/g fresh material, respectively and indicate improved uptake and incorporation of Se from SY. While selenocysteine (SeCys) was the main selenised amino acid in blood its concentration was not markedly affected by treatment, but the proportion of total Se as selenomethionine (SeMet) increased with increasing inclusion rate of SY. In milk, there were no marked treatment effects on SeCys content, but Se source had a marked effect on the proportion of total Se as SeMet. At day 112 replacing SS (T2) with SY (T3) increased the SeMet concentration of milk from 36 to 111 ng Se/g and its concentration increased further to 157 ng Se/g as the inclusion rate of SY increased further (T4) to provide 0.45 mg Se/kg TMR. Neither Se source nor inclusion rate effected the keeping quality of milk. At day 112, milk from T1, T2, and T3 was made into a hard cheese and Se source had a marked effect on total Se and the proportion of total Se comprised as either SeMet or SeCys. Replacing SS (T2) with SY (T3) increased total Se, SeMet and SeCys content from 180 to 340 ng Se/g, 57 to 153 ng Se/g and 52 to 92 ng Se/g, respectively. Key words: dairy cow, milk and cheese, selenomethionine, selenocysteine, milk keeping qualit