Selenium - NutraPedia

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Selenium: Uses, Benefits, and Genetic Considerations

1) Conditions Studied for Selenium

  • Thyroid disorders
  • Cancer prevention
  • Cardiovascular disease
  • Cognitive decline
  • Immune system enhancement

2) Efficacy in Treating Conditions

Research on selenium's effectiveness in treating conditions is mixed. While some studies suggest that it may provide benefits in managing certain conditions, such as thyroid disorders, other studies have not found significant evidence to support its widespread use for treating or preventing diseases like cancer or cardiovascular disease. More research is needed in this area.

3) Health Benefits of Selenium

  • Contributes to antioxidant activity and may reduce oxidative stress
  • Supports thyroid function and metabolism
  • Plays a role in the immune system
  • May have a role in preventing certain types of cancer

4) Potential Downsides of Selenium

Excessive intake of selenium can lead to selenosis, a condition characterized by symptoms like gastrointestinal upset, hair loss, white blotchy nails, and mild nerve damage. The recommended upper intake level should not be exceeded to avoid these adverse effects.

5) Selenium and Genetic Variations

Individuals with certain genetic variations may process selenium differently, which can influence the nutrient's impact on health. For example, variations in genes related to the selenium-containing enzymes may affect how selenium is utilized in the body. It's important to consider genetic makeup when evaluating selenium's potential benefits or risks.

Summary of Selenium's Impact on Health and Disease

Selenium and Cell Health: Research highlights the role of thioredoxin reductase, a selenoenzyme, in recycling the ascorbyl free radical to ascorbate (vitamin C) in cells, a process crucial for maintaining vitamin C levels. This activity is diminished in selenium-deficient conditions.

Selenium Deficiency and Kashin-Beck Disease: A meta-analysis associates significantly lower levels of selenium in individuals with Kashin-Beck disease compared to healthy controls, suggesting selenium deficiency as a risk factor for this degenerative bone condition.

Selenium and Gestational Diabetes: Lower serum selenium levels have been observed in pregnant women with gestational diabetes, indicating the potential benefit of selenium supplementation for those at risk.

Selenium and Glucose Metabolism: Various compounds, including selenate and selenite, are shown to affect glucose uptake in rat muscle, with implications for cellular responses to stress rather than insulin-like effects.

Selenium Levels and Breast Cancer: A significant association between lower selenium levels and an increased risk of breast cancer is found, highlighting selenium's potential as a predictor for the disease.

Selenium, Antioxidant Defense, and Preeclampsia: Selenium deficiency is linked to oxidative stress and preeclampsia in pregnant women, emphasizing the importance of selenium for antioxidant defense.

High-Dose Selenium Supplementation: A study on men with prostate cancer notes increased side effects with high-dose selenium supplementation but no serious toxicity, suggesting the need for further research on selenium's chemopreventive role.

Selenium Intake and Type 2 Diabetes: High dietary selenium intake is associated with an increased risk of type 2 diabetes in a Northern Italian population.

Selenium as an Insulin Mimic: Selenium's actions are compared to those of insulin, given its role in stimulating glucose uptake and regulating metabolic processes.

Thioredoxin System and Cancer: High expression of the thioredoxin system in aggressive cancers suggests its involvement in tumor proliferation and metastatic potential, presenting a potential therapeutic target.

Selenium and Thyroid Function: Selenium supplementation has been shown to affect thyroid function, indicating a need for careful consideration of supplementation in selenium-deficient populations.

Reactive Species and Cellular Damage: The paradoxical roles of reactive oxygen and nitrogen species in cell damage and defense are discussed, with implications for antioxidant therapies and disease prevention.

Conclusions

The studies collectively underscore the diverse roles of selenium in cellular health, disease prevention, and the potential risks associated with its supplementation. Selenium's involvement in enzymatic processes critical for reducing oxidative stress is highlighted, as is its complex relationship with conditions such as Kashin-Beck disease, gestational diabetes, breast cancer, and type 2 diabetes. Further research is necessary to fully understand the optimal levels of selenium intake for health benefits and to avoid potential adverse effects.

References:


  1. Reduction of the ascorbyl free radical to ascorbate by thioredoxin reductase
  2. Selenium and Iodine Levels in Subjects with Kashin-Beck Disease: a Meta-analysis
  3. Changes of serum selenium in pregnant women with gestational diabetes mellitus
  4. Insulin-like vs. non-insulin-like stimulation of glucose metabolism by vanadium, tungsten, and selenium compounds in rat muscle
  5. The relationship between selenium levels and breast cancer: a systematic review and meta-analysis
  6. Oxidative reactive species in cell injury: Mechanisms in diabetes mellitus and therapeutic approaches
  7. A prospective study of dietary selenium intake and risk of type 2 diabetes
  8. Selenium: an insulin-mimetic
  9. The thioredoxin-thioredoxin reductase system: over-expression in human cancer
  10. Reduced selenium concentrations and glutathione peroxidase activity in preeclamptic pregnancies
  11. A report of high-dose selenium supplementation: response and toxicities
  12. Selenium and its relationship to cancer: an update
  13. A 1-y trial of the effect of high-selenium bread on selenium concentrations in blood and toenails
  14. Evaluation of serum selenium levels in Turkish women with gestational diabetes mellitus, glucose intolerants, and normal controls
  15. The association between serum selenium and gestational diabetes mellitus: a systematic review and meta-analysis
  16. Thioredoxin reductase
  17. Relative abundance of selenoprotein P isoforms in human plasma depends on genotype, se intake, and cancer status
  18. No effect of modest selenium supplementation on insulin resistance in UK pregnant women, as assessed by plasma adiponectin concentration
  19. Selenium: a double-edged sword for defense and offence in cancer
  20. A randomized, placebo-controlled trial of selenium supplementation in patients with type 2 diabetes: effects on glucose homeostasis, oxidative stress, and lipid profile
  21. Does selenium supplementation affect thyroid function? Results from a randomized, controlled, double-blinded trial in a Danish population
  22. Free radicals and antioxidants in normal physiological functions and human disease
  23. Effects of long-term selenium supplementation on the incidence of type 2 diabetes: a randomized trial
  24. Possible protective effect of selenium against human cancer
  25. Comparison of serum trace element levels in patients with or without pre-eclampsia
  26. Role of oxygen radicals in DNA damage and cancer incidence
  27. Selenium, iodine, and the relation with Kashin-Beck disease
  28. Low selenium status is associated with the occurrence of the pregnancy disease preeclampsia in women from the United Kingdom
  29. A report of high-dose selenium supplementation: response and toxicities
  30. Letter Regarding: Selenium and Preeclampsia: A Systemic Review and Meta-Analysis
  31. Selenium in food and the human body: a review
  32. Loss of heterozygosity of the human cytosolic glutathione peroxidase I gene in lung cancer
  33. Selenium supplementation and the incidence of preeclampsia in pregnant Iranian women: a randomized, double-blind, placebo-controlled pilot trial
  34. Selenium deficiency as a model of experimental pre-eclampsia in rats
  35. Expression profiling and genetic alterations of the selenoproteins GI-GPx and SePP in colorectal carcinogenesis
  36. Serum selenium concentrations correlate significantly with inflammatory biomarker high-sensitive CRP levels in Hungarian gestational diabetic and healthy pregnant women at mid-pregnancy
  37. The relationship between plasma level of Se and preeclampsia
  38. Selenium content in selected foods from the Greek market and estimation of the daily intake
  39. Methioninase and selenomethionine but not Se-methylselenocysteine generate methylselenol and superoxide in an in vitro chemiluminescent assay: implications for the nutritional carcinostatic activity of selenoamino acids
  40. Serum selenium concentrations and diabetes in U.S. adults: National Health and Nutrition Examination Survey (NHANES) 2003-2004
  41. Acne vulgaris: the role of oxidative stress and the potential therapeutic value of local and systemic antioxidants
  42. An original discovery: selenium deficiency and Keshan disease (an endemic heart disease)
  43. In vitro and in vivo studies of methylseleninic acid: evidence that a monomethylated selenium metabolite is critical for cancer chemoprevention
  44. Selenium and Preeclampsia: a Systematic Review and Meta-analysis
  45. Selenocysteine beta-lyase and methylselenol demethylase in the metabolism of Se-methylated selenocompounds into selenide
  46. From selenium to selenoproteins: synthesis, identity, and their role in human health
  47. Contrasting patterns of regulation of the antioxidant selenoproteins, thioredoxin reductase, and glutathione peroxidase, in cancer cells
  48. Lung cancer risk associated with selenium status is modified in smoking individuals by Sep15 polymorphism
  49. Discoveries of vitamin B12 and selenium enzymes
  50. Acute selenium toxicity associated with a dietary supplement
  51. Nutritional selenium supplements: product types, quality, and safety
  52. Effects of long-term selenium supplementation on the incidence of type 2 diabetes: a randomized trial
  53. High dietary intake of sodium selenite induces oxidative DNA damage in rat liver
  54. Selenium biochemistry and its role for human health
  55. Methylselenol generated from selenomethionine by methioninase downregulates integrin expression and induces caspase-mediated apoptosis of B16F10 melanoma cells
  56. Selenomethionine: a review of its nutritional significance, metabolism and toxicity
  57. Selenium: from cancer prevention to DNA damage
  58. Inverse mRNA expression of the selenocysteine-containing proteins GI-GPx and SeP in colorectal adenomas compared with adjacent normal mucosa
  59. Increased risk of bladder cancer associated with a glutathione peroxidase 1 codon 198 variant
  60. Selenium in cancer prevention: a review of the evidence and mechanism of action
  61. An analysis of cancer prevention by selenium
  62. Allelic loss at the GPx-1 locus in cancer of the head and neck
  63. Discovery of the strong antioxidant selenoneine in tuna and selenium redox metabolism
  64. Predictors of selenium concentration in human toenails
  65. Xanthotrichia (yellow hair) due to selenium sulfide and dihydroxyacetone
  66. Role of glutathione peroxidase 1 in breast cancer: loss of heterozygosity and allelic differences in the response to selenium
  67. Selenium and preeclampsia: A global perspective
  68. Dietary selenium in humans toenails as an indicator
  69. Further observations on the human maximum safe dietary selenium intake in a seleniferous area of China
  70. Adverse health effects of selenium in humans
  71. Effects of the consumption of rice from non-KBD areas and selenium supplementation on the prevention and treatment of paediatric Kaschin-Beck disease: an epidemiological intervention trial in the Qinghai Province
  72. Baseline selenium status and effects of selenium and vitamin e supplementation on prostate cancer risk
  73. Selenoproteins and human health: insights from epidemiological data
  74. In vitro evaluation of selenium genotoxic, cytotoxic, and protective effects: a review
  75. A novel effect of selenium on streptozotocin-induced diabetic mice
  76. Analysis of Saccharomyces cerevisiae null allele strains identifies a larger role for DNA damage versus oxidative stress pathways in growth inhibition by selenium
  77. Selenium toxicity from a misformulated dietary supplement, adverse health effects, and the temporal response in the nail biologic monitor
  78. Predictors of toenail selenium levels in men and women
  79. Maternal and fetal cadmium and selenium status in normotensive and hypertensive pregnancy
  80. Selenium and human health
  81. Chromosome damage induced by selenium salts in human peripheral lymphocytes
  82. Selenoproteins and their impact on human health through diverse physiological pathways
  83. Effect of selenium on markers of risk of pre-eclampsia in UK pregnant women: a randomised, controlled pilot trial
  84. Free radicals, metals and antioxidants in oxidative stress-induced cancer
  85. Selenium and prostate cancer: systematic review and meta-analysis
  86. Alterations in gene expression profiles during prostate cancer progression: functional correlations to tumorigenicity and down-regulation of selenoprotein-P in mouse and human tumors
  87. Distribution and functional consequences of nucleotide polymorphisms in the 3'-untranslated region of the human Sep15 gene
  88. Structure-expression relationships of the 15-kDa selenoprotein gene. Possible role of the protein in cancer etiology
  89. Brazil nuts: an effective way to improve selenium status
  90. A brief overview of preeclampsia


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