Selenium is a trace element that is naturally present in the earth, it is found in certain foods, but also to a small extent in water.
Selenium is a very important trace element for the human body, since it increases the immune defense, is involved in the antioxidative activity against free radicals and inflammation and plays an important role in maintaining a healthy metabolism.
Advantages of selenium
According to studies, the generous consumption of naturally occurring selenium has positive antiviral effects and is crucial for successful male and female fertility and reproduction. Selenium also reduces the risk of cancer, autoimmune and thyroid diseases.
Selenium plays a protective role in the body because it has antioxidant properties and improves the quality of blood flow, which increases the body's resistance to disease and stress. Selenium is often praised for its role in antioxidant activity that reduces free radicals and inflammation.
This means that selenium supports the body by helping prevent regular forms of cancer, fighting viruses, fighting off heart diseases and others with serious illnesses and it slows down asthma-related symptoms.
It is believed that selenium deficiency is uncommon in healthy people in the United States. But people with certain diseases, such as HIV, Crohn's disease, and other disorders that affect nutrient intake, often have low selenium levels, which may result in selenium deficiency.
What forms of selenium are there?
Selenium is a trace element that is naturally present in many foods, added to others and is also available as a dietary supplement. Selenium, which is vital for human nutrition, is part of more than two dozen selenoproteins, which play a key role in the areas of reproduction, thyroid hormone metabolism, and DNA synthesis, as well as for protection against oxidative damage and infections.
Selenium exists in two forms: inorganic (selenate and selenite) and organic (selenium methionine and selenocysteine). Both forms are good sources of selenium. Soils contain inorganic selenites and selenates, which plants absorb and convert into organic forms - mostly selenocysteine ÿÿand selenium methionine and their methylated derivatives.
As selenium methionine, selenium is found primarily in animal and human tissues, where it can be absorbed non-specifically into body proteins with the amino acid methionine. The skeletal muscles are the main storage space for selenium since approximately 28-46% of the total selenium can be found here.
Both selenocysteine and selenite are reduced to generate selenium hydrogen, which in turn is converted into selenophosphate for selenoprotein biosynthesis.
Selenium is most often detected by measuring the plasma and serum selenium concentrations present in each case. The concentrations in blood and urine are related to the recent selenium uptake. Selenium analysis of hair or nails can be used to control long-term use lasting months or years.
The quantification of one or more selenoproteins (such as glutathione peroxidase and selenoprotein P) also serves for the functional measurement of the selenium status. Plasma or serum selenium concentrations of 8 micrograms (mcg)/dl or higher generally meet the requirements for selenoprotein synthesis in healthy people.
The Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board (FNB) at the Institute of Medicine of the National Academies (formerly the National Academy of Sciences) provide information on the recommended intake of selenium and other nutrients.
DRI is the general term for a series of benchmarks that are used in planning and assessing the nutrient intake of healthy people. These values, which vary depending on age and gender, include:
- Recommended daily dose/RDA value (according to the English abbreviation): the average daily intake, which corresponds to the nutritional requirements of almost all (97–98%) healthy people.
- Adequate intake/AI value: the value that is determined when there is insufficient scientific evidence to determine a recommended daily dose, instead indicating an amount that is believed to guarantee adequate intake.
- Estimated average daily requirement/EAR (according to the English abbreviation): the assumed average daily ration, which corresponds to the requirement of 50% of all healthy people. This value is usually used to assess the adequacy of the nutrient intake of certain populations, but it is not applied to individuals.
- Maximum Allowable Dose/UL: The maximum daily intake that is expected to have no adverse health effects.
Average daily intake (RDAs) of selenium:
- From birth to 6 months - 15 mcg*
- 7 to 12 months - 20 mcg*
- 1 to 3 years - 20 mcg
- 4 to 8 years - 30 mcg
- 9 to 13 years - 40 mcg
- 14 to 18 years - 55 mcg
- 19 to 50 years - 55 mcg
- Over 51 years old - 55 mcg
- Breastfeeding and pregnant women - 60 to 70 mcg
*Adequate intake (AI) - for infants from birth to 12 months, the FNB has established an intake of selenium that is given with the intake of selenium from healthy children who receive breast milk.
Selenium in food
The natural, selenium-rich food sources include Brazil nuts, eggs, liver, tuna, cod and sunflower seeds, but also poultry and certain types of meat.
Whole grains are also a good source of selenium, especially if they are handled and prepared with care, as selenium can otherwise be destroyed during processing and very high temperatures during cooking.
The amount of selenium present in a particular plant food source depends on the selenium content of the soil and a number of other factors. These include the soil pH and the presence of organic soil substances, but also the fact whether the selenium is in a form that is suitable for plant absorption. Accordingly, the selenium concentration in plant foods is very different - depending on the geographic location.
According to the U.S. Department of Agriculture's food composition database, Brazil nuts contain 544 mcg selenium/per about 30 grams, but the results of other analyzes vary significantly.
The selenium content of the soil, therefore, affects the selenium content of plants. These are in turn consumed by animals, so the amounts of selenium in animal products also differ from one another.
However, the selenium concentration in the soil has less of an impact on the selenium content of animal products than on plant food, since animals have predictable tissue concentrations of selenium due to homeostatic mechanisms. In addition, most of the animal feed contains the same proportion of selenium.
The following are 12 foods with the highest selenium content (percentages based on the RDA of 55 mcg/day for adults):
- Brazil nuts - one cup contains 607 mcg (1.103% DV)
- Eggs - 1 medium-sized egg contains 146 mcg (265% DV)
- Sunflower seeds - one cup contains 105 mcg (190% DV)
- Liver (from sheep or beef) - 85g contain 99 mcg (180% DV)
- Peter's fish - 85g contain 64 mcg (116% DV)
- Tuna - 85g contain 64 mcg (116% DV)
- Herring - 85g contain 39 mcg (71% DV)
- Chicken breast - 85g contain 33.2 mcg (58% DV)
- Salmon - 85g contain 31 mcg (56% DV)
- Turkey - 85g contain 25 mcg (45% DV)
- Chia seeds - 85g contain 15.6 mcg (28% DV)
- Mushrooms - one cup contains 15 mcg (27% DV)
Selenium as a food supplement
Selenium is available in multivitamin/multimineral supplements and as a single supplement - often as selenium methionine or selenium-enriched yeast, as well as sodium selenite or sodium selenate. The human body absorbs more than 90% of selenium methionine, but only about 50% of selenite derived from selenite.
Only a few studies have compared the relative absorption and bioavailability of the different forms of selenium. In one study, 10 groups of selenium-saturated people randomly received either a placebo or 200 or 600 mcg selenium daily in the form of selenium methionine, sodium selenite or high selenium-containing yeast (with an estimated 75% of the selenium being selenium methionine) over a period of 16 weeks.
The bioavailability of selenium based on urine excretion was greatest for selenium methionine and lowest for selenite. However, any form of these supplements only affected plasma selenium levels, but not glutathione peroxidase activity or selenoprotein P concentration. This confirmed that the study participants had sufficient selenium status before taking the selenium supplements.
Selenium deficiency causes biochemical changes that can make people who are already under additional stress vulnerable to the development of certain diseases. Soz. B. Selenium deficiency in combination with a second stress factor (such as a viral infection) for Keshan disease, a cardiomyopathy that occurred in parts of China prior to a government-sponsored selenium supplementation campaign in the 1970s.
Prior to the Chinese government-sponsored supplement program, adults in areas affected by Keshan disease showed an average selenium consumption of no more than 11 mcg per day. However, adults must consume at least 20 mcg daily to protect against Keshan disease.
Selenium deficiency is also linked to male infertility and could play a role in Kashin-Beck disease - a type of osteoarthritis that occurs in certain selenium-poor regions of China, Tibet, and Siberia. A lack of selenium may also exacerbate an iodine deficit, potentially increasing the risk of cretinism in infants.
Risk groups for selenium deficiency
Selenium deficiency is rare in the United States and Canada in Europe and China is more common. The following groups are among those most likely to have insufficient selenium intake.
People who live in poor selenium regions
The selenium consumption in North America is - even in selenium-poor regions - far above the RDA value. However, people in some other countries in the world, where the diet is primarily based on vegetables from selenium-poor growing areas, run the risk of developing deficiency symptoms. The world's lowest selenium intake is found in certain parts of China, where large parts of the population are predominantly vegetarian and the selenium level in the soil is very low.
The average selenium intake per day is also low in some European countries - especially where the population prefers a vegetarian diet. Although the intake quantity in New Zealand has been low in the past, it increased after the country increased imports of selenium-rich grain.
In patients who have to undergo long-term hemodialysis, the selenium level is significantly lower than in healthy people because hemodialysis removes selenium from the blood. In addition, hemodialysis patients run the risk of consuming small amounts of selenium due to anorexia due to urine poisoning and food restrictions.
Although selenium supplements increase blood counts in hemodialysis patients, further studies are needed to determine whether supplements have positive clinical effects in this group of people.
People with HIV
The selenium level is often low in HIV-infected people. This may be due to insufficient selenium intake (especially in developing countries) and excessive losses due to diarrhea and absorption disorders. Observational studies have found a link between low selenium concentrations in people with HIV and an increased risk of cardiomyopathy, death and - in pregnant women - HIV transmission to the unborn child and early childhood death.
Some randomized clinical trials of selenium supplementation in HIV positive adults have shown that selenium administration can reduce the risk of hospitalization and prevent an increase in HIV-1 viral load. Stopping HIV-1 viral load development may increase the number of CD4 cells, a type of infection-fighting white blood cell.
However, one study showed that selenium supplements in pregnant women can prevent the early death of the infant, but have no effect on the viral load and the mother's CD4 cell count.
Selenium can slow the progression of HIV
According to studies, the intake of daily selenium supplements in combination with traditional antiretroviral therapy may have a controlling effect on the viral load associated with HIV and increase the number of immune cells.
The study, which was published in the latest edition of the Archives of Internal Medicine, underscores the need for further research on the role of micronutrients in the treatment of AIDS while emphasizing that selenium is not a replacement for regular antiretroviral drugs, but it is potentially can supplement.
“As far as we know, this study is the first double-blind, randomized, placebo-controlled study in a community-based group of HIV-infected men and women to show that the daily supplemental intake of 200 micrograms of selenium over a period of nine months raises serum selenium levels and suppresses progression of HIV-1 viral load, ”wrote lead author Barry Hurwitz of the University of Miami.
The placebo-controlled, randomized and double-blind clinical study looked at the effects of a daily supplement of 200 micrograms of selenium yeast compared to placebo in 262 HIV-seropositive people with an average age of 40.6 years. The average number of CD4-T lymphocytes (cells of the immune system that are attacked by the virus) for the selenium and placebo groups was initially 417 and 441 cells per microliter of serum, while the average serum selenium level was 113 and 111 micrograms per liter scam.
One hundred and seventy-four volunteers followed the target for nine months and then participated in a nine-month follow-up. The selenium supplement group was found to increase selenium levels by 32.2 micrograms per liter, compared to only 0.5 micrograms per liter in the placebo group.
It was assumed that an increased selenium content in the blood would reduce the HIV viral load and, in turn, would increase the CD4 number.
"People treated with selenium, whose serum selenium increased by more than 26.1 micrograms per liter, demonstrated excellent adherence (86.2 percent), no change in HIV-1 viral load and a larger number of CD4 cells per microliter ( +27.9), "said the researchers.
According to their statements, no negative events related to selenium supplementation were reported.
"The exact method used to influence selenium's HIV-1 virus replication is not yet known, although the literature lists several options," the researchers wrote.
One hypothesis suggests that the antioxidant properties of selenium can possibly repair immune cell damage caused by oxygen since oxygen is produced more strongly in the body of HIV patients. However, further future research is required to confirm this connection.
The researchers called for further research to be carried out to find out whether the indirect effect of selenium on CD4 cell counts was limited to balancing the HIV-1 viral load and, if so, which methods are responsible.
"Given the challenges associated with traditional pharmacotherapy to achieve and maintain virological suppression of HIV disease, our results support the use of selenium as a simple, inexpensive, and safe adjunctive therapy," the authors concluded.
The study results were welcomed by AVERT, a UK-based international HIV and AIDS charity. The research “underlines the importance of selenium for the proper functioning of the immune system and gives good reasons for the use of selenium supplements in HIV-positive people.
Further long-term studies should now be undertaken to assess whether selenium supplements may cause a time delay before a person needs antiviral therapy.
Causes of selenium deficiency
Selenium is present in the soil and in food sources. There are actually 4 naturally occurring types of selenium minerals. These 4 natural selenium deposits are elemental selenium, selenide, selenite, and selenate.
Two of these forms, selenite, and selenite, are predominantly found in water, while the other two types of selenium occur in the soil and thus in food resources. For humans, the primary form of selenium supply is through food consumption, followed by intake via water and air.
The soil content of selenium varies depending on the location. For example, certain studies suggest that soil selenium levels are low in parts of Europe and Africa and that the population living in these areas may, therefore, suffer from immunodeficiency.
There is further evidence in other studies showing that a drop in selenium levels in the blood of people in parts of the UK and other countries in the European Union is causing concern for health professionals. Health authorities fear further potential health effects based on selenium deficiency.
Even with the same food sources, the amount of selenium largely depends on the soil conditions. Therefore, even within the same food, the selenium values are sometimes very different and the selenium's own advantages can be larger or smaller depending on where the crop is grown.
A selenium deficiency is associated with increased mortality risk, a weak immune system, and cognitive decline.
While the recommended daily dose of selenium for adults is 55 mcg per day, it is also believed that the average daily selenium intake in the US is 125 mcg, which by far fulfills the need. According to research, the US population of the eastern coastal plain and the Pacific Northwest has the lowest selenium level due to the prevailing soil conditions.
The local population consumes an average of 60 to 90 mcg selenium per day, which is still considered a sufficient amount, although it is less in comparison with other population groups from areas with selenium-rich soil.
Proof of selenium deficiency
If you suffer from a disease that could be dangerous due to a selenium deficiency, you should undergo a corresponding examination and determine whether taking additional selenium with a supplement would be beneficial. To determine your own current selenium level, you can have a blood or hair test carried out by your doctor.
However, a blood test only shows the amount of selenium that has been ingested recently. A hair examination also does not give an accurate general statement, since the trace element is stored differently in the various organs and systems.
For example, there is more selenium in the thyroid gland than anywhere else in the body because selenium plays a major role in metabolic processes.
Because experts do not often identify selenium deficiency in populations that generally do not have malnutrition or immunodeficiency, it is believed that there is little chance of suffering from a serious, disease-causing selenium deficiency, as long as natural selenium food sources are regularly included in the diet, and also is otherwise healthy.
Selenium and cancer
Because of its effects on DNA repair, apoptosis, the endocrine or immune system and other mechanisms - including antioxidant properties - selenium may also play a role in cancer prevention.
Epidemiological studies suggest an inverse association between selenium status and the risk of colon, prostate, lung, bladder, skin, esophagus and stomach cancer. In a Cochrane review of selenium and cancer prevention studies, the risk of cancer decreased by 31% in the category with the highest selenium intake compared to the category with the lowest selenium consumption. This group also had a 45% lower risk of dying from cancer and a 33% lower risk of developing bladder cancer.
In addition, the risk of developing prostate cancer in men decreased by 22%. The authors found no association between selenium consumption and a risk of breast cancer. A meta-analysis of 20 epidemiological studies showed a potential inverse relationship between toenail, serum and plasma soul values and a risk of prostate cancer.
Randomized controlled trials of selenium supplements for cancer prevention have produced conflicting results. Based on nine randomized clinical trials, the authors of a Cochrane review concluded that selenium may help prevent gastrointestinal cancer, but also indicated that these results were found inappropriately designed, randomized clinical trials should be confirmed.
A secondary analysis of a double-blind, randomized, controlled cancer prevention study involving 1,312 US adults with a medical history of basal cell or squamous cell carcinoma of the skin revealed that the intake of 200 mcg selenium per day in the form of baker's yeast containing selenium was associated with a 52–65% lower risk of prostate cancer over a period of 6 years.
This effect was most pronounced in men with the lowest tertile of selenium concentrations who had a prostate-specific antigen (PSA) of 4 ng/ml or lower at baseline.
The cancer prevention study based on selenium and vitamin E (SELECT) - a randomized, controlled study of 35,533 men aged 50 years or older from the United States, Canada, and Puerto Rico - was completed after 5.5 Years ago when analyzes showed no connection between a selenium supplementation of 200 mcg/day with or without the intake of 400 international units (IU) / day of vitamin E and a risk of prostate cancer.
A one and a half year follow-up of the participant data after the study-specific intake confirmed that there was no significant connection between selenium supplementation and prostate cancer risk.
In 2003, the FDA approved a qualified health claim for selenium-containing foods and supplements that said: "Some scientific evidence suggests that selenium consumption may reduce the risk of certain forms of cancer." The FDA has decided that the evidence available so far has been limited and inconclusive ".
More research is needed to confirm the relationship between selenium concentrations and cancer risk and to determine whether selenium supplements are actually helpful in preventing all types of cancer.
Selenoproteins help prevent the oxidative modification of lipids by reducing inflammation and preventing platelet accumulation. For these reasons, experts have suggested that selenium supplements may reduce the risk of cardiovascular disease or death related to cardiovascular disease.
However, the epidemiological data on the role of selenium in cardiovascular diseases have led to conflicting conclusions. Some observational studies have found an inverse relationship between serum selenium concentrations and the risk of high blood pressure or coronary heart disease.
A meta-analysis of 25 empirical studies found that people with lower concentrations of selenium had an increased risk of developing coronary artery disease.  Other observational studies, however, either did not find any statistically significant correlations between selenium concentrations and a risk of cardiac disease or cardiac death or found that higher selenium concentrations were associated with an increased risk of cardiovascular diseases.
Several clinical studies have examined whether selenium supplementation reduces the risk of developing cardiovascular complaints. For example, in a randomized, placebo-controlled study, 474 healthy adults aged 60 to 74 years, with an average baseline plasma concentration of 9.12 µg/dL, took supplements of 100, 200 or 300 mcg selenium over a period of 6 months a day or a placebo.
The dietary supplements caused a decrease in the levels of total plasma cholesterol and HDL plasma cholesterol (total cholesterol level minus the HDL values) in comparison to the placebo group, with the 300mcg daily dose significantly increasing the HDL level.
Other studies have shown that selenium supplements (200 mcg/day) or supplements in the form of multivitamin / multi-mineral tablets with selenium content (100 µg/day) do not reduce the risk of cardiovascular diseases or cardiac death.
A review of studies that used pure selenium supplements for primary prevention of cardiovascular diseases found no statistically significant effects of selenium with regard to fatal and non-fatal cardiovascular cases. Almost all participants in these clinical trials were well-fed male adults from the United States.
To date, the limited evidence provided by clinical studies does not support the use of selenium supplements for the prevention of heart diseases. This applies in particular to healthy people who are already sufficiently supplied with selenium through their food intake.
To better understand the contribution selenium derived from food and dietary supplements can make to cardiovascular health, further clinical studies are required.
Selenium and mental deterioration
Serum selenium concentrations decrease with age. Borderline or inadequate selenium concentrations may be associated with the age-related decline in brain function, which could be due to a decrease in the antioxidant activity of selenium.
The results of observational studies are very different. In two large studies, participants with lower initial plasma soul values were more likely to experience a cognitive decline over time. However, it is not clear whether the participants in this study had a selenium deficiency.
An analysis of the NHANES data from 4,809 older people in the United States found no relationship between serum selenium levels (which ranged from below 11.3 to over 13.5 µg/dl) and memory test results.
Researchers have investigated whether taking a selenium-containing antioxidant supplement reduces the risk of cognitive disorders in the elderly. An analysis of data from the study on “Supplémentation en Vitamine et Minéraux Antioxidydants (SU.VI.MAX)”, in which over 4,447 people between the ages of 45 and 60 participated in France, was found 6 years after the end of the study 8 years of daily dietary supplementation of 120 mg ascorbic acid, 30 mg vitamin E, 6 mg beta-carotene, 100 mcg selenium, and 20 mg zinc compared with placebo had better results in terms of episodic memory and semantic language skills.
However, the independent contribution of selenium to the observed effects of this study is not apparent. The authors of a systematic review, which included nine placebo-controlled studies, concluded that the clinical evidence available is insufficient to determine whether selenium supplements can prevent Alzheimer's disease.
Further evidence is required to answer the question of whether selenium supplements may help prevent or treat cognitive decline in the elderly.
Selenium and thyroid disorders
The selenium concentration in the thyroid gland is higher than in any other body organ. Just like iodine, selenium also plays an important role in hormone synthesis and thyroid metabolism.
Epidemiological evidence to indicate a relationship between selenium levels and thyroid function includes an analysis of the data recorded in the SU.VI.MAX study of 1,900 participants, which indicates an inverse relationship between selenium concentrations and thyroid volume, risk of goiter development and the Indicate risk of damage to thyroid tissue in people with mild iodine deficiency.
However, these results are only statistically significant for women. A cross-sectional study of 805 adults in Denmark with mild iodine deficiency found a significant inverse relationship between serum selenium concentration and thyroid volume in women.
Randomized, controlled studies on selenium supplementation in patients with thyroid disease have led to different results. In a randomized, double-blind, placebo-controlled study, 368 healthy adults aged 60 to 74 years received 100, 200 or 300 µg selenium/day for 6 months, which had no effect on the function of the thyroid gland despite a significant increase in plasma selenium levels.
Another randomized, double-blind, placebo-controlled study compared the effects of a 6-month administration of 200 mcg/day selenium (as sodium selenite), 1,200 mg/day pentoxifylline (an anti-inflammatory agent) or placebo in 159 patients with mild Graves' disease. eye disease. Compared to the patients treated with placebos, the patients testified that the selenium - but not pentoxifylline - received a higher quality of life.
In addition, ophthalmological results improved by 61% in the selenium-treated patient group, compared to 36% in the placebo group. Furthermore, only 7% of the selenium group showed little evidence of disease progression, compared to 26% of the placebo group.
Women with peroxidase antibodies tend to develop hypothyroidism during pregnancy and thyroid dysfunction after birth. The authors of a Cochrane review of hypothyroidism during pregnancy concluded that a selenium methionine supplement was used for 151 pregnant women with thyroid peroxidase antibodies on a daily basis with selenium methionine supplements containing 200 mcg this group represents a promising strategy, especially for the reduction of postpartum thyroiditis. Nevertheless, the authors called for extensive randomized clinical trials to provide high-quality evidence.
More research is needed to determine whether selenium supplementation can help with the prevention or treatment of thyroid disease.
The health benefits of selenium
Selenium is a trace element that ensures optimal health in appropriate doses. It is an important nutrient for a stable immune system, youthful appearance, and a keen mind - but at the same time, it is also an essential nutrient in the fight against cancer.
Selenium (Se) is a trace element that is found in poultry, fish, cereals, and eggs. It was thought to be a toxin until 1957, but current research shows that consuming an adequate amount of selenium has many obvious health benefits. Current scientific research is considering redefining the recommended selenium levels.
Plants absorb selenium from the ground. People around the world consume different amounts of selenium every day, depending on the mineral concentration in the surrounding region. For this reason, people suffer from selenium deficiency depending on their geographic environment.
There is a wide range of research on the health benefits of selenium - taking into account mood and cancer-related factors. There is also a link between selenium deficiency and a number of negative health complications.
1. Selenium fights inflammation
According to a review study, selenium inhibits NF-kB and its activation of interleukin-6, as well as TNF-alpha production.
Selenium can also reduce abnormally high levels of IL-8 and TNF-alpha.
2. Selenium supports the regulation of the biorhythm
Selenium facilitates the restoration of a disturbed day-night rhythm.
3. Selenium has anti-aging properties
Research has long highlighted the benefits of eating fish in terms of consuming polyunsaturated fatty acids. However, it is also possible that these benefits of frequent fish consumption are due to increased selenium concentrations.
Selenium, together with fatty acids, supports cognitive abilities and prevents polyunsaturated fatty acids from forming undesirable products.
In a recent study, the older participants (over 69 years) with the highest fish consumption and consequently the highest levels of selenium and polyunsaturated fatty acids had the best cognitive function.
There is also a correlation between low selenium status and cognitive decline.
In one study, people with Alzheimer's had only 60% of the selenium concentration out of the control group.
4. Selenium is important for thyroid function
If the body suffers from a selenium deficiency, the remaining stocks are concentrated in the tissue of the thyroid and brain. The thyroid gland has the highest selenium content per gram of tissue.
In patients with Hashimoto's thyroiditis, selenium supplements caused a significant reduction in thyroid peroxidase (TPO) antibodies compared to a placebo.
Also in patients suffering from Hashimoto's thyroiditis and pregnant women with anti-TPO antibodies, the selenium addition led to a decrease in antibody levels and improved the structure of the thyroid gland, as shown by ultrasound examinations. In addition, patients with Graves' disease found faster remission thanks to selenium supplementation.
Women with lower iodine values had a larger thyroid volume, the risk of goiter was greater and the risk of damage to the thyroid tissue was larger due to the low selenium blood levels.
5. Selenium prevents cancer
Selenium prevents cancer in many ways. Increased but non-toxic concentrations of selenium have shown that this reduces the risk of colon, prostate and lung cancer. Selenium is able to prevent cancer cell formation or to stop its cell cycle.
Although there are links between selenium intake and cancer prevention, the genetics, gender and age of the patient, together with the stage and type of cancer, also influence the preventive effects of selenium.
According to current research, enough selenium is consumed in America, which reduces the likelihood of developing cancer. A longitudinal study found that over a period of eight to ten years, selenium reduced the risk of death in individuals suffering from lung, colon and prostate cancer.
In another study conducted on people with skin cancer, selenium also reduced mortality. Those who received selenium instead of a placebo in the study had a 50% lower cancer mortality rate in the case of non-melanous cancer.
A combination of milk thistle (silymarin) and selenium significantly reduced LDL and total cholesterol in men who had their prostate removed. These markers are used to determine the risk factors for prostate cancer progression.
6. Selenium helps the immune system (especially against viruses)
A lack of selenium can cause the body to have an abnormal immune response. An increased selenium supply also enables the destruction of tumor cells and helps the body to produce antibodies. In addition, a selenium deficiency is also associated with the progression of viral infectious diseases.
Otherwise harmless viruses can develop a dangerous potential in people with a selenium deficiency. As a result, selenium deficiency may lead to cardiomyopathy, making it difficult for the heart to supply blood to the rest of the body.
With a sufficient selenium level, the body has strong cellular immunity, so that the immune cells are less prone to death or damage.
If the selenium level is significantly below its ideal level, cells are subject to stress. Cell death activates the virus and enables it to replicate more quickly.
By inhibiting virus replication, selenium also helps in the fight against HIV. A person's selenium status can serve as a predictor of the outcome of the disease: selenium-deficient patients are almost 20 times more likely to die from HIV-related causes than those with normal selenium levels.
In children, low selenium levels not only increase the likelihood of dying from HIV but also allow the disease to spread faster.
7. Selenium is beneficial for Th2-dominant people
Selenium supplements can also help redirect immune responses to the Th2 type associated with allergies and asthma and help promote Th1. This creates protection against viral infections and cancer.
8. Selenium supports fertility and reproductive health
In animals, selenium deficiency is associated with an increased likelihood of miscarriage. Women who miscarried in the first third of their pregnancy were also more likely to have low selenium levels.
Selenium also affects male fertility because it is necessary for the formation and development of sperm. In sub-fertile men who received selenium supplements for three months, sperm motility increased significantly.
Selenium is important for the synthesis of testosterone in rats, but it does not lead to an increase in testosterone as long as a person is adequately supplied with it.
Eleven percent of the men in this study who took the selenium supplements became fathers, while none of the men who received placebos fathered children.
9. Selenium improves the state of mind
Selenium affects the cells of the nervous system and thus affects mood. Neurotransmitter turnover is slower in people with selenium deficiency.
Low selenium levels are associated with depression, anxiety, disorientation, and hostility.
Elderly people in the hospital, as well as cancer and/or HIV patients, reported less anxiety after selenium was added to their diet.
In a 15-week short-term study, people with a low selenium level had lower individual scores in the areas of "clear thinking" and "joyful mood" when testing their mood. People with a selenium-rich diet, on the other hand, recorded high ratings in the categories "clear thinking", "confident" and "relaxed".
10. Selenium increases IGF-1
An Italian study in adults aged 65 years and older found a positive and significant association between selenium and IGF-1.
Selenium used to treat hypothyroidism
A healthy thyroid is an important part of overall health. However, many people struggle with thyroid disorders, such as hypothyroidism, especially with the autoimmune disease Hashimoto's thyroiditis.
The immune system attacks the thyroid gland, causing the inflammation that results in an underactive thyroid gland or hypothyroidism. Hashimoto's thyroiditis is the most common form of hypothyroidism and was the first disease ever to be classified as an autoimmune disease.
A lot has been written about thyroid health and a variety of environmental factors, such as gluten, gut health, stress, excess iodine, and vitamin D deficiency, have been highlighted that can affect thyroid function.
It also discussed why changing diet is always the first step in treating Hashimoto and why thyroid hormone replacement is often necessary for a successful outcome.
But there is another nutritional factor that may play a role in thyroid health: selenium.
Selenium deficiency is considered uncommon in healthy adults and is more likely to be found in people with digestive problems such as Crohn's disease or celiac disease, as this results in only a low absorption of the nutrients. However, people with severe inflammation due to chronic infections can also have a selenium deficiency.
It is believed that a selenium deficiency does not in itself cause a specific disease, but it makes the body more susceptible to diseases caused by other nutritional, biochemical or infectious stress factors due to the task that selenium performs in the context of the immune system function.
Adequate selenium-rich diet supports the efficiency of thyroid hormone synthesis or metabolism and protects the thyroid gland from damage caused by excessive iodine exposure.
Several scientific studies have demonstrated the benefits of selenium supplements in the treatment of autoimmune thyroid disorders. One study found that selenium supplements had a significant impact on the inflammatory activity of thyroid-specific autoimmune diseases, although the reduction in inflammation may limit the damage to the thyroid tissue.
This may be due to the increase in activity with glutathione peroxidase and thioredoxin reductase, as well as the decrease in the toxic concentrations of hydrogen peroxide and lipid hydroperoxide - results of thyroid hormone synthesis.
Another study followed patients over a period of 9 months and found that selenium supplementation reduced the antibody level of thyroid peroxidase in the blood - even in patients with selenium deficiency.
Even if these studies are promising for the use of selenium supplements to prevent damage to the thyroid tissue, further research is still needed to determine the long-term clinical effects of selenium treatment in inflammatory autoimmune thyroid disease.
In addition, selenium is also necessary for the conversion of T4 to T3, since deiodase enzymes (those enzymes that remove the iodine atoms from T4 during the process) are selenium-dependent. T3 is the active form of thyroid hormone and a low T3 level can cause hypothyroid symptoms.
A double-blind intervention study showed that selenium supplementation regulated selenium deficiency in people with selenium deficiency, which is theoretically based on an improvement in peripheral T3 conversion.
In cases of severe selenium deficiency, T4/T3 conversion may be affected, which can lead to symptoms of hypothyroidism. If the thyroid fails to convert to T3, it becomes apparent how dependent this process is on selenoproteins and that a significant selenium deficiency can cause hypothyroidism symptoms.
So the question is: should you start taking selenium supplements if you have hypothyroidism, Hashimoto's thyroiditis, or a low T3 level?
As is so often the case, the answer is: it depends. While these preliminary studies show the positive effects of selenium supplements on inflammatory activity in autoimmune thyroid disease, the long-term effects of supplementation on thyroid health are still unknown.
We know that selenium is an important component of the enzymes responsible for converting T4 to T3, but whether a supplement causes an increase in serum T3 levels is unclear.
While it appears that selenium supplements are obviously a solution in the event of poor thyroid function, long-term consumption of high selenium doses can lead to complications such as gastrointestinal upset, hair loss, white spotty nails, garlic-like breath odor, fatigue, irritability, and slight nerve damage. In addition, selenium supplementation with low iodine levels may even worsen hypothyroidism.
Consciously maintaining optimal selenium intake may give both the immune system and the thyroid the stimulus they need to function better. It is extremely important for people with thyroid disorders to pay attention to an adequate selenium level.
Health risks from excessive selenium intake
There is plenty of evidence of selenium's health benefits. With a normal dosage, selenium usually shows no negative side effects. However, high doses can have health consequences.
1. Excessive selenium intake can promote type II diabetes. Type II diabetes and elevated blood sugar have a positive correlation with selenium.
When factors such as gender, weight, and age were checked, there was a connection between high selenium levels and type II diabetes.
However, the relationship between diabetes and selenium is not exactly easy to describe. Women who have diabetes during pregnancy have a lower selenium concentration than is usually the case in pregnant women.
The different results regarding the relationship between selenium and diabetes underline the fact that excessive selenium, selenium that is not normally dosed, is diabetes-promoting.
2. An excess of selenium may decrease the active thyroid hormone T3 in men.
An investigation found that too much selenium (300 mcg) caused a T3 reduction in men, but a larger study was unable to replicate these results.
Chronically high recordings of organic and inorganic selenium compounds show similar effects. Early indicators of excessive intake include a garlic-smelling breath and a metallic taste in the mouth. The most common clinical symptoms of chronically high selenium intake or selenosis include hair and nail loss or brittleness.
Other symptoms include skin and nervous system lesions, nausea, diarrhea, rashes, spotty teeth, fatigue, irritability, and abnormalities in the nervous system.
As already mentioned, Brazil nuts contain very high amounts of selenium (68-91 mcg per nut) and could lead to selenium poisoning if consumed regularly.
Acute selenium toxicity can cause severe gastrointestinal and neurological symptoms, acute respiratory distress syndromes, myocardial infarction, hair loss, muscle sensitivity, tremors, drowsiness, flushing of the face, kidney and heart failure and in rare cases even death.
The FNB has determined for the selenium derived from food and supplements Upper Levels (ULs) on the basis of the selenium content associated with the brittleness of hair and nails.
Tolerable intake (ULs) for selenium: 
From birth to 6 months - 45 mcg
- 7 to 12 months - 60 mcg
- 1 to 3 years - 90 mcg
- 4 to 8 years - 150 mcg
- 9 to 13 years - 280 mcg
- 14 to 18 years - 400 mcg
- 19 to 50 years - 400 mcg
- Over 51 years old - 400 mcg
- Breastfeeding and pregnant women - 400 mcg
The maximum allowable amount (UL) for selenium is 400mcg per day for adults.
Some immediate indications of selenium overdose are indigestion and neurological symptoms (including tremors), drowsiness, flushing, muscle pain and shortness of breath. The more severe reactions include e.g. heart attack, heart failure, kidney failure and very rarely death.
Curcumin protects against selenium poisoning of the liver and kidneys.
Selenium can interact with certain medications, while some medications may also have a negative effect on selenium levels. An example of this is cisplatin, a medication used for cancer of the ovaries, bladder, lungs, and others. Cisplatin can reduce selenium status in serum and hair. However, it is not yet known whether this has clinical effects.
People who take cisplatin or other medication on a regular basis should discuss their selenium level with the doctor.