Selenium: benefits, dosage, contraindications
Other name(s)
Se, Selenium
Family or group:
Minerals and trace elements
Indications
Scoring methodology
EFSA approval.
Selenium deficiency ✪✪✪✪✪
Selenium deficiencies occur when daily dietary intakes are very low, especially for geographic reasons (soils low in selenium). Several studies consider that an intake of 90 µg is necessary to achieve maximal activity of plasma glutathione peroxidase. Moreover, given that there are several selenoproteins whose synthesis is regulated differently depending on selenium intake, some researchers believe this amount is not sufficient. Finally, numerous studies demonstrate the benefit of an additional intake beyond the nutritional intake to reduce cancer risk. The average daily intake level defined by EFSA is 70 µg per day, and the maximum chronic daily intake is 300 µg per day.
Posologie
Oral administration
70 - 300 µg
Adults
Male fertility disorders ✪✪✪✪✪
Selenium is essential for male fertility and necessary for the biosynthesis of testosterone and spermatogenesis. Indeed, the selenoprotein of sperm nuclei, of the GSHPx 4 type, is an antioxidant enzyme that protects spermatozoa from oxidative damage and, due to its polymerization in mature spermatozoa, has a structural role preserving the stability and motility of spermatozoa. The EFSA has also established that selenium contributes to normal spermatogenesis.
Posologie
Oral administration
70 - 300 µg
Adults
The importance of selenium to human health.
The argument for increasing selenium intake
Thyroid balance ✪✪✪✪✪
Selenium is necessary for the synthesis, activation, and metabolism of thyroid hormones. The thyroid gland has a higher concentration of selenium than any other organ in the body. Selenium is an essential component of the iodothyronine deiodinase enzyme that converts thyroxine (T4) into triiodothyronine (T3). In people who are iodine-deficient, a selenium deficiency can exacerbate hypothyroidism. However, giving selenium alone in this situation may still worsen hypothyroidism because the conversion of T4 to T3 is increased while the thyroid gland lacks iodine to synthesize more T4. Selenium may also be able to prevent the alterations in thyroid hormone levels that are sometimes observed in patients after trauma EFSA, for its part, has established that selenium contributes to the normal functioning of the thyroid.
Posologie
Oral
70 - 300 µg
Adults
The importance of selenium to human health
Influence of selenium supplements on the post-traumatic alterations of the thyroid axis: a placebo-controlled trial
Role of thyroid hormones in the effects of selenium on mood, behavior, and cognitive function
Selenium deficiency mitigates hypothyroxinemia in iodine-deficient subjects
Scientific Opinion on the substantiation of health claims related to selenium and protection of DNA, proteins and lipids from oxidative damage (ID 277, 283, 286, 1289, 1290, 1291, 1293, 1751), function of the immune system (ID 278), thyroid function (ID 279, 282, 286, 1289, 1290, 1291, 1293), function of the heart and blood vessels (ID 280), prostate function (ID 284), cognitive function (ID 285) and spermatogenesis (ID 396) pursuant to Article 13(1) of Regulation (EC) No 1924/20061
Selenium-induced thyroid dysfunction
Oxidative stress ✪✪✪✪✪
At plasma concentrations below 1000 mcg/L, selenium activates glutathione peroxidase (GSH-Px), which reduces oxidative stress by neutralizing free radicals and hydrogen peroxide. At concentrations above 2000 mcg/L, selenium paradoxically increases cellular oxidation by promoting the formation of reactive oxygen species (ROS), such as hydroxyl radicals and superoxide. At higher concentrations, selenium also promotes intracellular formation of nitric oxide, which is converted into toxic nitrous oxide. To reduce the effect of ROS formation, selenium is often administered with other antioxidants, such as vitamin E or vitamin C. Preliminary evidence suggests that selenium and vitamin E act synergistically as antioxidants, and may also synergistically inhibit the growth of prostate cancer cells. Selenium may reduce inflammation by lowering cellular concentrations of reactive oxygen species (ROS). In the case of liver transplantation, ROS are generated when the organ is reperfused with blood after a prolonged period of warm ischemia. Preliminary evidence suggests that selenium's antioxidant action may reduce liver injury and improve microcirculation. Selenium may act as part of a defense mechanism by reducing oxidative stress in the gastroduodenal ulcer. EFSA has determined that selenium contributes to the protection of cells against oxidative stress.
Posologie
Orally
70 - 300 µg
Roles of Se and NO in apoptosis of hepatoma cells
Scientific Opinion on the substantiation of health claims related to selenium and protection of DNA, proteins and lipids from oxidative damage (ID 277, 283, 286, 1289, 1290, 1291, 1293, 1751), function of the immune system (ID 278), thyroid function (ID 279, 282, 286, 1289, 1290, 1291, 1293), function of the heart and blood vessels (ID 280), prostate function (ID 284), cognitive function (ID 285) and spermatogenesis (ID 396) pursuant to Article 13(1) of Regulation (EC) No 1924/20061
Selenium compounds have disparate abilities to impose oxidative stress and induce apoptosis
Interactions of selenium compounds with other antioxidants in DNA damage and apoptosis in human normal keratinocytes
Antioxidant dietary supplements: Rationale and current status as chemopreventive agents for prostate cancer
Influence of selenium therapy on liver microcirculation after warm ischemia/reperfusion: an intravital microscopy study
Hair beauty ✪✪✪✪✪
EFSA has established that selenium contributes to the maintenance of normal hair and nails.
Posologie
Oral administration
70 - 300 µg
Immune support ✪✪✪✪✪
Selenium enhances immune function by increasing interleukin-2 (IL-2) activity and promoting the normal growth and development of helper T cells. These actions may be important in the management of acquired immunodeficiency syndrome (HIV) because selenium deficiency is common in this condition. There is preliminary experimental evidence that selenium inhibits reverse transcriptase and the replication of the human immunodeficiency virus (HIV). However, there is also evidence that selenium may improve subjective feelings of well-being in patients infected with HIV, but it does not appear to affect overall outcomes. Selenium deficiency is associated with increased viral shedding in women infected with HIV. Dietary selenium intake in these women may reduce the transmission of AIDS. There is also evidence suggesting that selenium deficiency may increase inflammatory lung damage caused during influenza virus infection. Selenium may also protect patients infected with hepatitis B or C from developing liver cancer. EFSA has established that selenium contributes to the normal functioning of the immune system.
Posologie
Orally
70 - 300 µg
The importance of selenium to human health
Selenium deficiency increases the pathology of an influenza virus infection
Scientific Opinion on the substantiation of health claims related to selenium and protection of DNA, proteins and lipids from oxidative damage (ID 277, 283, 286, 1289, 1290, 1291, 1293, 1751), function of the immune system (ID 278), thyroid function (ID 279, 282, 286, 1289, 1290, 1291, 1293), function of the heart and blood vessels (ID 280), prostate function (ID 284), cognitive function (ID 285) and spermatogenesis (ID 396) pursuant to Article 13(1) of Regulation (EC) No 1924/20061
Selenium and interleukins in persons infected with human immunodeficiency virus type 1
Pregnancy ✪✪✪✪✪
A meta-analysis of three clinical trials shows that taking selenium at 60-100 mcg per day for up to 6 months reduces the risk of preeclampsia by 72% compared to placebo in pregnant women. Another analysis showed that the risk of preeclampsia is higher in pregnant women with low selenium levels.
Posologie
Oral administration
70 - 100 µg
Pregnant women
Selenium and Preeclampsia: a Systematic Review and Meta-analysis.
Selenium, Zinc, and Manganese Status in Pregnant Women and Its Relation to Maternal and Child Complications
Prostate cancer ✪✪✪✪✪
A slight decrease in prostate cancer risk is observed in areas with high soil selenium levels (an indicator of dietary selenium intake) compared with those with low soil selenium levels.nnIn clinical trials, results are conflicting regarding the effect of selenium on prostate cancer risk. nnIn one large clinical trial, taking selenium 200 µg/day for 4.5 years significantly reduced the relative risk of prostate cancer by 63% compared with placebo. However, this benefit appears to be limited to patients with selenium deficiency. In another large clinical trial, taking selenium 200 µg/day for an average of 5.5 years did not significantly reduce the risk of prostate cancer compared with placebo in men with normal PSA (prostate-specific antigen) levels.nn
Posologie
Oral
70 - 200 µg
4 - years
Men
Synergies
Synergistic effect of vitamin E and selenium in human prostate cancer cell lines
Study of prediagnostic selenium level in toenails and the risk of advanced prostate cancer.
Association between alpha-tocopherol, gamma-tocopherol, selenium, and subsequent prostate cancer.
Serum selenium and subsequent risk of prostate cancer.
Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT).
Baseline characteristics and the effect of selenium supplementation on cancer incidence in a randomized clinical trial: a summary report of the Nutritional Prevention of Cancer Trial.
Selenium and prostate cancer: systematic review and meta-analysis.
Plasma selenium level before diagnosis and the risk of prostate cancer development.
Selenium supplementation, baseline plasma selenium status and incidence of prostate cancer: an analysis of the complete treatment period of the Nutritional Prevention of Cancer Trial.
Chronic lymphocytic thyroiditis ✪✪✪✪✪
Clinical studies have shown that daily intake of 200 µg of selenium in combination with levothyroxine significantly reduced thyroid peroxidase (anti-TPO) antibodies by approximately 6% to 30% compared with placebo in adults with thyroiditis after 3 to 12 months of treatment. (Doses lower than 200 µg per day may not be as effective.) However, clinical research conducted in affected children suggests that taking 50-200 µg of selenium per day, also for 3 to 12 months, does not significantly reduce thyroid peroxidase (anti-TPO) antibodies.
Posologie
Oral
70 - 200 µg
1 - years
Adults
Emotional balance ✪✪✪✪✪
A low dietary intake of selenium has been associated with a higher incidence of anxiety, depression, and fatigue. Several studies have examined the relationship between higher dietary intake or selenium supplementation and improvement in mood and reduction in anxiety. Some double-blind studies have shown that short-term selenium supplementation (100 mcg/day) resulted in a significant improvement in mood, and a decrease in anxiety, depression, and fatigue.
Posologie
Oral
100 µg
8 - weeks
Adults
Hypothyroidism ✪✪✪✪✪
Low selenium levels or selenium deficiency appear to reduce the conversion of thyroxine (T4) to triiodothyronine (T3).nnMoreover, selenium intake can worsen hypothyroidism in people with iodine deficiency. Indeed, selenium increases the conversion of T4 to T3, but the thyroid gland lacks iodine to synthesize additional T4.nnPeople deficient in iodine and selenium should receive selenium and iodine supplementation at the same time to avoid worsening hypothyroidism.nnOn the other hand, selenium has no significant effect on thyroid function when iodine intake is adequate.nnSome clinical research has shown that daily intake of 200 µg of selenium during pregnancy appears to reduce by 41% the risk of postpartum thyroid dysfunction, and by 42% the risk of permanent hypothyroidism, compared with placebo, in euthyroid pregnant women with thyroid peroxidase antibodies (autoantibodies present in inflammatory thyroid disorders).nn
Posologie
Oral administration
70 - 200 µg
Adults
Selenium-induced thyroid dysfunction.
Selenium deficiency mitigates hypothyroxinemia in iodine-deficient subjects.
The influence of selenium supplementation on postpartum thyroid status in pregnant women with thyroid peroxidase autoantibodies.
Low selenium status in the elderly influences thyroid hormones.
Selenium status in an iodine deficient population of the West Ivory Coast.
Rheumatoid arthritis ✪✪✪✪✪
The results of clinical studies regarding the effects of selenium on rheumatoid arthritis (RA) are contradictory. Some clinical research suggests that taking selenium-enriched yeast at 200 µg/day slightly improves quality of life without changing objective measures of RA. Other clinical research suggests that taking 200 µg of selenium per day for 3 months improves joint swelling, pain, and morning stiffness, and reduces the need for corticosteroids and nonsteroidal anti-inflammatory drugs to control symptoms in patients with RA.
Posologie
Oral administration
70 - 200 µg
3 - months
Adults
selenium-enriched yeast
HIV infection ✪✪✪✪✪
There is contradictory evidence regarding the effect of selenium on HIV. Some clinical evidence shows that taking 200 µg of selenium per day for up to 2 years may slow the increase in viral load, increase CD4 cell counts, and reduce the number of hospitalizations in HIV-positive men and women. However, other evidence shows that taking 100-200 µg of selenium daily does not reduce the risk of opportunistic infections and does not improve CD4 counts or viral load in HIV-positive patients, including pregnant women.
Posologie
Oral administration
70 - 200 µg
24 - months
Adults
One-year antioxidant supplementation with beta-carotene or selenium for patients infected with human immunodeficiency virus: a pilot study.
Randomized, double-blind, placebo-controlled trial of selenium supplements among HIV-infected pregnant women in Tanzania: effects on maternal and child outcomes.
Psychological burden in the era of HAART: impact of selenium therapy.
Impact of a selenium chemoprevention clinical trial on hospital admissions of HIV-infected participants.
Detoxification ✪✪✪✪✪
Aside from its role as an antioxidant, selenium contributes to the detoxification of xenobiotics and certain heavy metals by forming metal-selenide complexes.
Posologie
Orally
70 - 300 µg
Adults
Properties
Antioxidant
Glutathione peroxidases (GSHPx), selenoproteins that function as antioxidant enzymes, are one of the main lines of defense against damage caused by oxygen free radicals. GSHPx are chemically different but share the same role of detoxifying reactive oxygen species (hydrogen peroxide and organic hydroperoxides). They therefore inhibit the production of highly oxidizing free radicals. Their enzymatic activity is directly proportional to selenium intake, and there is therefore a close link between selenium deficiency and oxidative stress.
Usages associés
Essential
Selenium has a fundamental importance in human health. It is an essential trace element, the active center of numerous selenoproteins; it is mainly involved in antioxidant defense systems, thyroid metabolism, and immune function. Overt selenium deficiencies occur when daily dietary intakes are very low, particularly for geographic reasons (selenium-poor soils). In selenium deficiency, one observes a decrease in plasma Se, erythrocyte or platelet glutathione peroxidase (GSHPx), a cellular inability to metabolize peroxides, macrocytosis, hemolysis, changes in enzymatic activities reflecting liver and muscle function, immune disorders, elevated T4 concentrations, etc. Clinically, one or more of the following symptoms may be observed during deficiency: dystrophy of skeletal muscles, depigmentation of skin appendages (hair and nails), anemia, arthritic manifestations, delayed neurological development, increased frequency of infections, or even cardiac arrhythmia. They are generally reversible with selenium administration. Two diseases have been associated with severe endemic selenium deficiency: juvenile Keshan cardiomyopathy and Kashin-Beck chondrodystrophy.
Usages associés
Immunomodulatory
Selenium acts as a modulator of inflammatory and immune responses by helping to maintain regulation of peroxide concentration at the site of inflammation, by decreasing leukotriene production, and by stimulating cellular immunity. Selenium deficiency has been associated with decreased immune function. Moreover, selenium supplementation in an individual whose selenium deficiency is not apparent stimulates the immune response.nn
Usages associés
Effect on fertility
Selenium is essential for male fertility and necessary for the biosynthesis of testosterone and for spermatogenesis.nnIndeed, the selenoprotein of sperm nuclei, of the nnGSHPx 4 type, is an antioxidant enzyme that protects spermatozoa from oxidative damage and, through its polymerization in mature spermatozoa, plays a structural role preserving sperm stability and motility.nn
Usages associés
Anticancer
At supranutritional doses (at least 200 µg/day), selenium has pharmacological therapeutic properties, particularly in oncology (prostate, colon, and lung cancers).nnThe anticancer effect of selenium appears to be closely linked to its enhancement of the immune response and also to the production of metabolites such as methylselenol, which would disrupt the metabolism of cancer cells (gene expression, DNA damage and repair, signaling pathways, regulation of the cell cycle and apoptosis, metastasis, and angiogenesis).nn
Usages associés
Hormonal metabolism
The deiodinase, another characterized type of selenoprotein, has helped explain why selenium is essential in the action of thyroid hormones. nnIndeed, two deiodinases (5'DI, 5'DII) are enzymes that convert the prohormone thyroxine T4 into triiodothyronine T3, the hormonally active form at the tissue level. The deiodinase (5 DIII) inactivates thyroxine by converting it into its inactive metabolite, reverse triiodothyronine rT3, and also mediates the conversion of T3 into diiodothyronine.nnFurthermore, there is a very close interrelationship between selenium metabolism and that of iodine. In fact, it has been demonstrated in Central Africa that the prevalence of iodine deficiencies is much higher among populations with low selenium status than among those with adequate selenium status.nn
Usages associés
Antiviral
Selenium deficiency appears to increase the virulence or progression of certain viral infections. In Keshan disease (a rare cardiomyopathy secondary to selenium deficiency), it appears that a coxsackievirus is a cofactor in the development of the cardiomyopathy. Experiments in selenium-deficient mice have shown that inoculation with this normally harmless virus induces a mutation in the viral genome responsible for a cardiovirulent form. nnFurthermore, the increase in oxidative stress resulting from selenium deficiency could induce mutations or changes in the expression of certain viral genes. Thus, selenium deficiency appears to be involved in the progression of HIV infection. It has been shown that selenium can be a potential inhibitor of HIV replication in vitro.nn
Usages associés
Cognitive function
Many lines of evidence indicate that selenium is important in the brain: in cases of deficiency, it is highly preserved in this tissue. There is a relationship between the decline of cognitive function and decreased selenium status in older adults; it may also play a role in mood.
Usages associés
Depurative
Selenium protects against the toxicity of certain metals such as cadmium, arsenic, lead, silver and mercury. Indeed, it has been shown that inorganic selenium enhances the toxic effects of inorganic arsenic by increasing its retention in tissues and suppressing its metabolism in vitro.
Usages associés
Safe dosage
Child aged 1 to 3 years: 15 µg - 60 µg
Child aged 4 to 6 years: 20 µg - 90 µg
Child aged 7 to 10 years: 35 µg - 130 µg
Pregnant woman aged 18 and older: 70 µg - 300 µg
Adolescent aged 15 to 17 years: 70 µg - 250 µg
Child aged 11 to 14 years: 55 µg - 200 µg
Adult aged 18 and older: 70 µg - 300 µg
Breastfeeding woman aged 18 and older: 85 µg - 300 µg
Interactions
Médicaments
Antiplatelet agents/Anticoagulants: moderate interaction
Selenium may increase bleeding time by stimulating the production of prostacyclin. Selenium may also interact with warfarin by displacing it from albumin binding sites, by reducing its metabolism in the liver, or by decreasing the production of vitamin K-dependent clotting factors.
Barbiturates: moderate interaction
Selenium may inhibit the hepatic metabolism of barbiturates.
Immunosuppressant: moderate interaction
Theoretically, selenium supplementation may interfere with immunosuppressive treatment due to its immunostimulatory activity.
Plantes ou autres actifs
Selenium: moderate interaction
Zinc reduces selenium absorption by forming zinc selenite complexes.
