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6Selenium (Se) - Body & Health Importance + Top 30 Sources
Eliseeva Tatyana, editor-in-chief of the EdaPlus.info project E-mail: [email protected]
Abstract. The article discusses the main properties of selenium ( Se ) and its effect on the human body. A systematic review of modern specialized literature and relevant scientific data was carried out. The best natural sources of selenium are indicated . The use of the mineral in various types of medicine and the effectiveness of its use in various diseases are considered. The potentially adverse effects of selenium on the human body under certain medical conditions and diseases are analyzed separately.
Key words: selenium, Se , benefit, harm, beneficial properties, contraindications
Selenium is a mineral that is beneficial in small amounts. Scientists are just beginning to study its role in health, which is why doctors and nutritionists talk so little about it. But researchers have already proven that the microelement helps to produce antioxidants to protect against cancer, improves mental activity, boosts immunity, and supports hormone production. These are not the only reasons to regularly replenish the supply of the substance - its deficiency can lead to many diseases in children and adults.
Selenium in the body: intake and reserves
The mineral regulates the secretion of thyroxine and insulin, is an important component of 30 different selenoprotein proteins and the enzyme glutathione peroxidase, necessary to fight free radicals. It protects cells from infections, takes part in the creation of DNA, reproductive and other functions. [one]
The component is not synthesized by the body, but is stored in tissues and organs after intake with food. The highest concentrations are observed in the thyroid gland, but these reserves are constantly consumed for the synthesis of hormones. Most of the compound is stored in skeletal muscles - from 28 to 46%. [2]
Tests to detect selenium deficiency
You can determine the status of a mineral in the body by measuring its concentration in the blood. However, this figure reflects recent consumption, not stocks. To assess long-term intake, analysis of nails and hair helps. In some cases, the level of glutathione peroxidase is measured - its lack is associated with a nutrient deficiency. [3, 4]
Journal.edaplus.info - Журнал здорового питания и диетологии Selenium in food: types and absorption
There are two forms of trace elements:
• organic - selenomethionine and selenocysteine;
• inorganic - selenate, selenite. [5]
Both forms can be present in the diet, but some studies show that organic compounds are much better absorbed. Inorganic species are often found in the soil - plants accumulate them and convert them into organic ones. [6, 7]
What foods contain selenium?
The main food sources of the mineral: Brazil nuts, seafood, offal. It gets into plant foods from the soil, so the amount in products varies depending on the geographical location. [eight]
Animals get the trace element from food of plant origin. However, its content in meat products is more stable than in plants. This happens due to homeostatic mechanisms - animals maintain certain reserves in tissues.
15 animal products with the highest concentration of selenium [9]
No. Product mcg in 100 g
1 Pork kidneys, stewed 310
2 Beef kidneys, boiled 168
з Turkey liver, stewed 102
4 Octopus boiled В9
5 Mussels boiled 89
6 Chicken liver, fried 88
7 Salted mackerel 7з
В Lobsters boiled 7з
9 Canned tuna 70
10 Clams boiled 64
11 Salted herring 58
12 Turkey heart, cooked 56
1з Halibut baked 55
14 Sardine in oil 52
15 Caviar red, black 51
Vegans get the mineral from nuts, whole grains, legumes, and tofu. They can fully satisfy the body's need for a beneficial compound without nutritional supplements.
15 Selenium-Rich Plant Foods [9]
No. Product mcg in 100 g
1 brazil nuts 1916
2 Air wheat grains 123
3 Sunflower seed, roasted 79
4 Wheat bran 77
5 chia 55
6 Chinese shiitake mushrooms, dried 46
7 Oat bran 45
8 Wheat germinated, raw 42
9 Rye bread 36
10 Whole wheat noodles, boiled 36
11 White bread crackers 36
12 Sesame seeds 34
13 Table mustard, paste 33
14 Couscous boiled 27
15 Pita 27
Top 100 Natural Sources of Selenium
Most of the mineral in Brazil nuts - one kernel exceeds the daily requirement of the body. They should be added to the diet with caution, since with regular consumption there is a risk of poisoning. [ten]
Daily intake of selenium
Overdose with normal diets, like deficiency, is extremely rare - a healthy diet protects against such problems. Babies get it in sufficient quantities with mother's milk, infant formula and cereals. But adults who are prescribed supplements by doctors should carefully study their compositions to protect against overdose.
Daily intake of selenium [11]
Life period Age Men and women (mcg)
babies
0-6 months
fifteen
Children
from 7 months to 3 years twenty
Children
4-8 years
thirty
Children
9-13 years old
40
Teenagers and adults 14+
55
The Tolerable Upper Intake Level per day for adults is 400 micrograms. You can exceed the threshold in case of excessive consumption of Brazil nuts, multivitamins.
The daily requirement for selenium increases for women in two cases:
• pregnancy - 60 mcg;
• breastfeeding - 70 mcg.
Cases in which the daily requirement for a mineral decreases are still unknown to scientists and doctors.
7 Benefits of Selenium Backed by Science
1. Neutralizes free radical activity
The mineral has antioxidant properties - protects cells from oxidative stress, prevents them from damage by free radicals. The latter are formed daily as a result of metabolic processes and are beneficial until they accumulate in excess. Antioxidants neutralize excess oxidizing agents and thus protect against many diseases. [12, 13]
2. Reduces the risk of cancer
There is a link between high levels of selenium in the blood and reduced risks of breast, lung, colon, and prostate cancer. Dietary supplements with it also improve the quality of life of cancer patients during irradiation - they reduce problems with the gastrointestinal tract, diarrhea. [14, 15, 16]
3. Protects Against Heart Disease
Human studies show that with a 50% increase in blood levels of a microelement, the risk of heart disease is reduced by 24%. It has been proven that taking food supplements with the component increases the level of the powerful antioxidant glutathione peroxidase and reduces the concentration of C-reactive protein, an inflammatory marker that provokes diseases of the cardiovascular system. [17, 18]
4. Supports brain function
Oxidative stress leads to multiple sclerosis, Parkinson's and Alzheimer's. Several tests have also shown that people with dementia have reduced blood levels of selenium, and taking it improves memory. Based on numerous studies, scientists have concluded that a diet with sufficient content of the element can prevent mental decline. [19, 20]
5. Affects the functioning of the thyroid gland
Thyroid tissue contains more of the mineral than any other organ. She needs selenium to protect against oxidative stress and produce hormones. A study involving 6,000 people shows that the lower its concentration, the higher the risk of autoimmune thyroiditis and hypothyroidism. [21]
6. Supports Immunity to Fight Potential Threats
Scientists have confirmed that a high level of a microelement in the blood enhances the immune response, and its deficiency worsens. Supplements with a nutritional ingredient also strengthen the immunity of people with influenza, hepatitis C, tuberculosis, HIV. [22, 23, 24]
7. Reduces Asthma Symptoms
Asthma is inextricably linked to oxidative stress and high levels of inflammation in the body. Since the mineral suppresses inflammation, it also reduces the symptoms of asthma: chest tightness, shortness of breath, cough. Even lung function is better in those asthmatics who have a higher concentration of the microelement in the blood. [25, 26, 27, 28]
Interaction of selenium with other nutrients
• Its deficiency can exacerbate iodine deficiency, thereby increasing the risk of dementia, a problem with physical and mental development in infants.
• Selenium is more effective as an antioxidant when combined with vitamin E, as their functions are interrelated. [29]
• Complements the beneficial properties of sulfur and together with it is part of many amino acids. [thirty]
Selenium in medicine
The mineral is available in multivitamins and as separate supplements in the form of selenomethionine, selenite, and sodium selenate. The human body absorbs more than 90% of selenomethionine and about 50% of selenite. All forms are used to treat thyroiditis, high cholesterol. Mineral nanoparticles are also used in the production of nanodrugs for cancer patients - they are used as a means for delivering drugs to the desired organs. [31]
Selenium in scientific research
1. In the mid-1990s, scientists reported that a 200 mcg/day supplement given to prevent recurrence of non-melanoma skin cancer also reduced the risk of prostate, lung, and colon cancer. During testing, they found that selenomethionine was more effective. [32]
2. Studies have shown that selenium has a positive effect on cognitive function in the elderly and is especially needed during pregnancy. Consuming enough of the mineral during pregnancy has positive consequences for both children aged 1.5 years and for 5-10 year olds - the higher the consumption status, the higher the mental abilities of schoolchildren. [33]
3. A small study found that eating one brazil nut a day improved verbal fluency and other mental functions in patients with mild cognitive impairment. A natural product, no worse than dietary supplements, fights against microelement deficiency and can be part of therapy - it is recommended for older people to maintain cognitive functions. [34]
4. Taking selenium supplements daily for three months reduces thyroid antibodies. A positive effect is observed in people with chronic autoimmune thyroiditis - non-infectious inflammation in the thyroid gland. After therapy, patients not only improve their tests, but also their mood and general well-being. [35]
5. Studies in the United States have shown that increasing your intake of the mineral can halve the incidence of prostate cancer. A meta-analysis confirmed that the component plays the role of a protector - it prevents the development of malignant tumors and their growth. [36]
Side effects of selenium: harm and toxicity
The benefits of taking a nutrient can only be obtained if the recommended doses are observed. Any deviations negatively affect health.
Selenium Deficiency Symptoms
The lack of a useful compound is rare and even less likely to provoke diseases in adults - it takes years to develop them. Some population groups are at risk:
• people living in regions with a deficiency of the element in the soil (for example, in several regions of China);
• patients on kidney dialysis; [37]
• HIV patients; [38]
• people with digestive disorders such as Crohn's disease.
The last three factors impair the absorption of selenium by the body. Deficiency leads to biochemical changes and creates additional stress for the body, weakens it:
• provokes Keshan's disease - selenium-deficient cardiomyopathy; [39]
• can cause male infertility;
• causes osteoarthritis. [40]
Symptoms of excess selenium
The first signs of chronically high consumption of the substance:
• garlic breath and metallic taste;
• hair loss;
• fragility of nails;
• skin rash;
• damage to the nervous system - fatigue, irritability;
• nausea and diarrhea;
• stains on teeth.
Acute toxicity develops as a result of misuse of over-the-counter drugs and causes myocardial infarction, muscle pain, tremors, dizziness, facial flushing, kidney and heart failure, and, in rare cases, death.
The interaction of selenium with drugs
Scientists have established a link between the microelement and cisplatin, a drug that is used in chemotherapy to treat various types of cancer. It can reduce the level of the trace element in the hair and blood serum, but it is not known how critical the indicators can be. At the same time, small studies show that the supplement with the mineral reduces the toxicity of the drug. [41]
Low selenium levels in people living in certain regions make them more susceptible to viral diseases. Dietary supplements with the element increase the body's resistance to infections, reduce the risk of
cancer. Therefore, many countries use it with concern for the population. For example, Finland adds the mineral to fertilizers to increase its content in food, and Sweden adds the mineral to lakes to get rid of methylmercury in fish (the concentration of the toxin decreased by 75% in three years).
Expert comment
Tatyana Eliseeva, nutritionist, nutritionist
While selenium deficiency is rare, it's important to make sure you're getting enough of it from food and that you don't have problems absorbing it. Before taking supplements, you need to talk with your doctor or nutritionist - recommendations for taking differ in different countries and depend on lifestyle, health status.
Literature
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An extended HTML version of this article is available on the edaplus.info website .
Selenium (Se) - Body & Health Importance + Top 30 Sources
Eliseeva Tatyana, editor-in-chief of the project EdaPlus.info
E-mail: [email protected]
Received 10.02.2022
Abstract. The article discusses the main properties of selenium ( Se ) and its effect on the human body. A systematic review of modern specialized literature and relevant scientific data was carried out. The best natural sources of selenium are indicated . The use of the mineral in various types of medicine and the effectiveness of its use in various diseases are considered. The potentially adverse effects of selenium on the human body under certain medical conditions and diseases are analyzed separately.
