Selenium Deficiency: What Foods Are Needed To Fill It

Free radicals are molecules that have lost an arm or a leg (and in the words of biochemistry - an ion) molecules that strive, having selected the missing part of the body, to become full again. The most powerful factory for their production is the mitochondrial electron transport chain - a place where, in essence, due to the coordinated work of five complexes and the processes of oxidation and phosphorylation, energy is produced - in the form of ATP.

The most famous donor of "arms" and "legs" in the human body is tocopherol - vitamin E - a truly amazing substance: sharing the missing ions with free radicals, it itself retains its normal structure and functions. No less important defenders are glutathione, retinol, flavonoids, ascorbic acid. However, there are also antioxidant enzymes: catalase, superoxide dismutase, glutathione peroxidase and glutathione reductase - selenium plays an undeniable role in the functioning of the last two.

The name of this element, discovered more than two hundred years ago, is translated as “moon” - and in this, no doubt, besides being an inspiration for poets, perhaps there is another, much deeper meaning: after all, how can a night be imagined without a month and stars, and the normal functioning of the whole organism largely depends on the content of this substance.

The role of selenium in the human body

1. Antioxidant protection - is part of the following enzymes:

   • Glutathione peroxidase - consists of 4 subunits, each of which contains a selenium atom in the form of selenocysteine. The task of this enzyme is to catalyze the synthesis of glutathione, the main defender of the body (especially fatty acids, erythrocytes, hemoglobin, membranes, and DNA) from the damaging effects of peroxides.

   • Glutathione reductase - catalyzes the conversion of the oxidized form of glutathione into the reduced one and thereby prevents the development of oxidative stress.

   • Thioredoxin reductase - carries out the reduction of thioredoxin, a low molecular weight protein that is also able to withstand oxidative stress. Mice with its overexpression showed greater resistance to inflammatory processes, as well as a longer lifespan.

   Research: Supplementation of Micronutrient Selenium in Metabolic Diseases: Its Role as an Antioxidant

2. Inhibits apoptosis (programmed cell death) through complex stepwise biochemical reactions.

3. Participates in the conversion of thyroxine (T4), a thyroid hormone, into the more metabolically active triiodothyronine (T3), being part of deiodinase.

   Changes in thyroid function as a result of insufficient selenium intake can lead to poor mood, behavioral and cognitive impairment.

4. Slows down the aging process.

5. Reduces the manifestations of symptoms that occur during menopause.

6. It shows synergy and enhances the action of vitamin E - their combination has shown more effective results in protecting mitochondria, cytochromes, microsomal membranes.

7. Selenium is also used in the treatment of HIV - taking 20 μg of the drug for 9 months was associated with suppression of the virulence of the virus, as well as an increase in the number of T-helpers (recall that it is precisely at them that the barrel of a gun is aimed at in this disease).

8. It contributes to the normal course of hematopoietic processes (controls oxidative stress during erythropoiesis, and also affects several stages of erythroid development as part of selenoproteins).

   Study: Selenium Status and Hemolysis in Sickle Cell Disease Patients

Lipid metabolism disorders and selenium

Hyperlipidemia (that is, abnormally high concentrations of lipoproteins in the blood) may be due to genetic diseases, but in most cases it is caused by other metabolic disorders and is quite often associated with obesity and diabetes.

Studies have shown that healthy individuals with a diet rich in selenium (above 82.4 mcg/day) had lower levels of sialic acid (which plays a significant role in immune response mechanisms, carcinogenesis and inflammatory processes), as well as triglycerides.

It is also thought that selenium levels in red blood cells may be indicative of a decrease in total and low-density lipoprotein cholesterol after menopause.

In rats with hyperlipidemia induced by diazinon (one of the most common acetylcholinesterase-inhibiting insecticides), sodium selenite supplementation (at 200 µg/kg body weight) normalized cholesterol, urea, and creatinine levels, which may be due to the induction of antioxidant enzymes.

In laboratory rodents, as noted by another study, the development of hyperlipidemia was facilitated by a decrease in the absorption of selenium in the intestine under the influence of nicotine. The addition of selenium as a supplement to their diet improved the pathological condition - this is evidenced by a decrease in the expression of hydroxymethylglutaryl-CoA reductase (catalyses the formation of mevalonic acid in cholesterol synthesis reactions) and other enzymes of lipogenesis.

Selenium and the thyroid gland

The thyroid gland contains the largest amount of selenium per 1 gram of tissue compared to other organs and systems of the body.

For the synthesis of thyroid hormones, the processes of iodination of tyrosine amino acid residues in the thyroglobulin molecule are necessary - this occurs on the apical membrane (or near it) under the action of the thyroperoxidase enzyme - in this case, the presence of hydrogen peroxide (H2O2) is a prerequisite.

The formation of H2O2 is potentially dangerous for thyrocytes (thyroid cells) and is believed to be regulated by TSH (thyroid stimulating hormone) through intracellular messengers that trigger complex cascade processes.

In the absence of TSH, the secretion of glutathione peroxidase (namely type 3) at the apical pole of the thyrocyte leads to a decrease in the concentration of peroxide through its decomposition to water molecules. On the contrary, in the presence of thyrotropin, the formation of this antioxidant enzyme decreases and, as a result, the amount of H2O2 available for thyroperoxidase increases - iodination reactions occur.

With a lack of selenium and iodine in the diet, another very important trace element, a fairly common endemic disease develops - myxedematous cretinism. It is accompanied by thyroid atrophy and leads to mental retardation.

Iodine is a necessary substrate for the synthesis of thyroid hormones. Accordingly, with a decrease in its concentration in the body, a decrease in the synthesis of thyroxine and triiodothyronine is also observed. This, by a negative feedback mechanism, leads to increased secretion of TSH by the pituitary gland, which, as previously mentioned, increases the formation of hydrogen peroxide. The selenium deficiency observed in this case affects the decrease in the activity of glutathione peroxidase.

At the same time, against the background of developing hypothyroidism in the brain, the activity of type 2 deiodinase increases - to maintain a locally normal concentration of triiodothyronine, which is necessary for neurological and mental development.

Thus, we draw your attention to the fact that replenishment of selenium reserves without first eliminating the iodine deficiency only exacerbates the symptoms.

In addition, it should also be noted that selenocysteine ​​is present in the thyroid deiodinase (that is, sulfur is replaced by selenium in the amino acid structure of cysteine) - and in many people this transformation is impaired, which leads to a lack of function of the organ itself.

New studies also highlight the need for selenium supplementation in autoimmune thyroid disease: for example, in patients with Hashimoto's disease and in pregnant women with antibodies to thyroperoxidase (TPO), there was a decrease in the level of specific immunoglobulins and an improvement in the overall ultrasound structure of the organ. Moreover, the risk of postpartum thyroiditis was significantly reduced.

Diseases associated with selenium deficiency

1. A study in which 2,000 people from China took part showed that a low concentration of this trace element in the nails was associated with a decrease in intelligence - this prompted scientists to think about the relationship between selenium deficiency and Alzheimer's disease.

2. Selenium increases the activity of macrophages and the production of immunoglobulins (antibodies), and also increases cytolysis by natural killer cells.

   Accordingly, its moderate deficiency is associated with a decrease in immunity and, as a result, increased susceptibility to pathogens.

3. Long-term selenium deficiency has a negative effect on the functioning of the cardiovascular system and may be one of the main causes of myocardial infarction - this assumption was based on the study of two endemic diseases:

   • Diseases of Keshan and Kashin-Bek, first identified in women of reproductive age, as well as in children in the provinces of China, where a significant decrease in the concentration of selenium was noted in the soil and agricultural products.

   • Keshan's disease was accompanied by degeneration of the heart muscle, and Kashin-Bek's disease was accompanied by osteoarthritis, which led to atrophy and necrosis of the cartilage tissue of the joints.

4. Selenium deficiency is associated with the development of depression and anxiety disorders.

1. The lack of this mineral in pregnant women can lead to various fetal malformations.

2. Selenium is also very important for the reproductive system: in rats on a diet deficient in this trace element, the appearance of abnormal spermatozoa was noted for two generations.

   With a severe selenium deficiency, rodents became infertile due to the cessation of spermatogenesis and degeneration of the epithelium of the seminiferous tubules.

   Interestingly, when they administered selenium preparations, most of it accumulated in the middle part of the spermatozoon, where the mitochondrial helix is ​​located.

   Research: Selenium. Role of the Essential Metalloid in Health

3. Studies note that patients with low blood selenium levels associated with vitamin E deficiency are at an increased risk of developing cancer.

   It is believed that these effects of selenium are associated with a change in the mechanism of interaction between carcinogens and DNA, an increase in detoxification processes, a selective slowdown in energy metabolism in tumor cells, as well as a change in the permeability of cell membranes and an immunostimulating effect.

4. There is also a slow growth in children and pathology of the surfactant system of the lungs.

5. Hemoglobin oxidation and hemolytic anemia.

Prevalence of selenium in the environment

In the environment, selenium is found in the elemental state, as well as in the forms of selenides, selenites and selenates, which differ somewhat in chemical structure from each other. It is noteworthy that the transition of this microelement to neighboring states is quite easy and occurs under the influence of the pH of digestive juices, humidity, redox potential, and depending on the concentration of free oxygen.

Circulating in nature, this element initiates the processes of rock weathering. It is emitted into the atmosphere with volcanic gases, and its biomethylation by microorganisms also plays a certain role in this.

Calculation of the daily dose

For a long time, selenium was considered toxic. Indeed, poisoning with it led to anemia, hair loss, and blindness - these symptoms were observed in areas where the content of this mineral in the soil exceeded its average concentration by 1000 times. Moreover, it is a sulfur antagonist and is able to replace it in amino acids (cysteine ​​and methionine), which can lead to disruption of enzymes.

The optimal daily dose for the normal course of biochemical and physiological processes is 55 mcg for adults (as recommended by WHO).

The U.S. Food and Nutrition Council notes that the amount of selenium consumed should vary with age and be 40-70 micrograms for men, 45-55 micrograms for women, and 25 micrograms for children.

It is noted that the total amount of this mineral in the human body varies from 3 to 20 mg, with about 47% of the total amount found in skeletal muscles, while the kidneys account for only 4%.

The content of selenium in serum gradually decreases in persons over 60 years of age.

At serum concentrations below 85 mcg / l, a deficiency is observed, which is associated with an increased risk of prostate cancer by 4-5 times.

Food Sources of Selenium

Plants accumulate selenium in the form of inorganic compounds (in particular selenates), which are then converted into organic compounds (selenocysteine, which predominates in animal food, and selenomethionine).

Selenium is absorbed most easily in organic form, as well as in the presence of vitamins A, D, E and low molecular weight proteins containing methionine.

The following foods are rich in selenium:

• Cereals - the content of selenium in them, it is worth noting, largely depends on the concentration of this mineral in the soil (and most European countries are just at risk).

• Meat.

• Dairy.

• Milk - modified baby milk contains four times less selenium than breast milk (3.5 mcg enters the child's body daily compared to 13.3 mcg of this element in mother's milk).

• Nuts.

• Fish - it is noted that marine species caught in the northwestern part of the Atlantic Ocean contain more selenium (168-825 ng/g) compared to freshwater species (146-576 ng/g).

• Eggs - depending on the diet of chickens. Selenium in the yolk is associated with phosphoavidin.

• Bread.

• Asparagus.

• Mushrooms.

• Garlic.

Small amounts of inorganic selenium (selenite and sodium selenate - the bioavailability of the latter, by the way, is excellent, and it is directly used for the synthesis of certain selenoproteins) have been found in drinking water.

The low content of protein in foods is associated with a low concentration of selenium in them.

Cereals cover about 50% of the daily intake of selenium, while meat, poultry and fish - about 35%. Fresh and unprocessed vegetables provide 11% of this micronutrient in a proper, balanced diet, fruits less than 10%.

Heavy metals and sulfur reduce the bioavailability of this element, as does heat treatment (due to the formation of volatile compounds).

The use of supplements containing organic selenium of yeast origin, in case of its deficiency, has multidirectional beneficial effects on the health and functioning of the human body (in particular, on the functioning of the thyroid gland and the cardiovascular system). It is also considered the safest form.

It is recommended to add fermented foods to the diet, which contain lactic acid bacteria, as well as yeast, which accumulate a significant amount of selenium. Another example is sourdough baking using microbial cultures enriched with selenium.

With the syndrome of malabsorption, radiation and chemotherapy, metabolic disorders, the risks of its deficiency are especially increased.

An interesting fact: not only nutrihacking experts, but also manufacturing enterprises and large farms have recently begun to pay attention to this microelement. It has been noted that selenium is necessary for the normal reproductive function of chickens, for the formation of quality eggs (in particular, the optimal ratio of protein and yolks, as well as for shell hardness), as well as for protecting the body from free radicals.

Studies note that the addition of selenium to animal feed effectively protects against high blood pressure with regular exposure to heavy metals. In particular, necrotic damage to the kidneys under the influence of mercury decreased with increased selenium intake.

Laboratory diagnostics

1. Increased TSH (thyroid-stimulating hormone).

   Optimum: 1-1.9 honey / l.

2. Decreased T4.

   The free T4 optimum is mid-lab reference and above.

3. Decreased T3.

   Optimum: mid-reference.

4. You can see the level of selenium in the blood serum or do a spectral analysis of hair for trace elements.

5. Urinalysis for iodine (they are synergists with selenium).

Selenium deficiency test

Selenium deficiency can also be detected at home. To conduct the test, you will need hydrogen peroxide (H2O2), which is always in the medicine cabinet, and clean, dry hands.

Apply a 3% solution of hydrogen peroxide (H2O2) to the pads of your fingers and then monitor the reaction of the skin. If there is enough selenium in the body, then the skin will not change its appearance; if the amount of the mineral corresponds to the lower limit of the norm, then small whitish spots will appear on the fingertips; the presence of a clear deficiency will confirm the association of these spots into a solid white area around the entire perimeter of the phalanx.