Selenium is one of the 15 essential nutrients in the human body, selenium deficiency in the human body can cause many serious diseases, more than 40 countries around the world are in selenium deficiency areas, hundreds of millions of people in 22 provinces in China are in selenium deficiency or low selenium zone, the population of these areas has a high incidence of tumors, liver diseases, cardiovascular diseases and so on. The total amount of selenium in adults is 6 to 20 mg. Selenium is found throughout tissues, organs and body fluids, with the highest concentration in the kidneys. It exists mainly within tissues in the form of complexes bound to selenium and proteins. Selenium is mainly absorbed in the small intestine, and the absorption rate of selenium in food by the human body is 60% to 80%. Selenium absorbed into the body through the intestine is mostly excreted in the urine after metabolism. Urinary selenium is a good indicator of selenium in the human body. Other routes of selenium are fecal and sweaty. The absorption, transport, discharge, storage and distribution of selenium in the body are affected by many external factors. Mainly the chemical form and amount of selenium in the diet. In addition, gender, age, health status. The recommended intake for people over 18 years of age is 50 μg/day, the appropriate intake is 50-250 μg/day, and the maximum tolerated intake is 400 μg/day.
The role of selenium.
First, the composition of antioxidant enzymes in the body, can be mentioned to protect the cell membrane from oxidative damage, to maintain its permeability; second, selenium-P protein has chelated heavy metals and other poisons, reducing toxicity of poisons
Selenium is known as the "king of cancer prevention" in the human trace elements, and the level of blood selenium is related to the occurrence of cancer. With a daily selenium supplement of 200 μg, cancer mortality decreased by 50% and the overall incidence of cancer by 37%, of which lung cancer decreased by 46%, bowel cancer by 58%, and prostate cancer by 63%. Selenium can reduce the risk of cancer" and "selenium can produce anti-cancer effects in the human body". Selenium inhibits cancer cell growth and their DNA RNA and protein synthesis, inhibits the transcription of oncogenes, and interferes with the metabolism of carcinogens."
Selenium is a component of glutathione peroxidase (GSH-Px), which can prevent oxidative destruction of islet β cells, make them function normally, promote sugar metabolism, reduce blood sugar and urine glucose, and improve the symptomatic effect of diabetic patients.
The retina is susceptible to damage due to contact with computer radiation, etc. Selenium can protect the retina, enhance the finish of the vitreous body, improve vision, and prevent cataracts.
Selenium is an important free radical scavenger (50--500 times that of vitamin E) eliminates toxins in the body, antioxidants, can effectively inhibit the production of peroxidated lipids, prevent blood clots, remove cholesterol, and enhance human immune function.
Due to the high antioxidant effect of "selenium", appropriate supplementation can play a role in preventing organ aging and lesions, delaying aging, enhancing immunity, and resisting diseases.
Selenium is an important element in maintaining the normal function of the heart and has a protective and repairing effect on the heart body. The decrease in the level of blood selenium in the human body will lead to the decline of the function of scavenging free radicals in the body, resulting in an increase in the deposition of harmful substances, an increase in blood pressure, a thickening of the blood vessel wall, a decrease in the elasticity of blood vessels, a slower blood flow rate, and a decrease in oxygen delivery function, thereby inducing an increase in the incidence of cardiovascular and cerebrovascular diseases.
Selenium prevents bone marrow end lesions and promotes repair, while in protein synthesis it promotes disulfide bonds against the detoxification of metallic elements. It has a good preventive and therapeutic effect on arthritis patients.
Selenium binds strongly to metals and resists cadmium's toxicity to the kidneys, reproductive glands and central nervous system. Selenium binds to heavy metals such as mercury, lead, tin and thallium in the body.
The lower the selenium content in the body, the greater the likelihood of stomach disease, the higher the likelihood that patients with superficial gastritis will often have a lower body selenium content than healthy people, and the atrophic gastritis patients with low selenium content in the blood will be "cancerous" Greatly increase the likelihood that most gastric cancer patients are in a state of selenium deficiency.
The decrease in selenium levels in the human body will cause loss of immune function and antioxidant capacity to decline, causing the gastric mucosal barrier to be unstable, xanthine oxidase will continue to rise in emergency situations, causing ischemic damage to the gastric mucosa, increased oxygen radicals, resulting in gastritis, gastric ulcers and other digestive system lesions, selenium is a natural antioxidant, can effectively inhibit the production of reactive oxygen species, remove garbage produced in the process of human metabolism - free radicals, prevent gastric mucosal necrosis, promote the repair of the mucous membrane and the healing of ulcers, prevent cancer, so, Taking a certain amount of selenium every day will help patients with chronic stomach disease to control their condition and alleviate the symptoms of stomach disease.
Selenium is an excellent adjuvant of radiotherapy and chemotherapy, and taking selenium in cancer patients during chemoradiation can play a multifaceted role. Selenium supplementation can improve the immunity of radiotherapy and chemotherapy patients, so that the patient body has enough ability to successfully complete radiotherapy and chemotherapy, the improvement of immunity is also conducive to helping tumor patients recover as soon as possible, while preventing tumor metastasis and recurrence, selenium supplementation can not only reduce nausea, vomiting, gastrointestinal disorders, loss of appetite, severe hair loss and other toxic side effects of radiotherapy and chemotherapy, but also reduce the decline of white blood cells caused by chemotherapy. Taking a larger dose of selenium preparations before and after chemotherapy, the total number of white blood cells and neutrophils are significantly higher than those without selenium preparations, selenium supplementation can prevent drug resistance during radiotherapy and chemotherapy, and selenium can relieve the toxic effects of chemotherapy drugs in cancer patients.
Selenium is very important for brain function, selenium deficiency makes some "neurotransmitters" metabolic rate change, while the body produces a large number of harmful substances free radicals can not be removed in time, thereby affecting the body's brain function, and increasing selenium will not only reduce the occurrence of epilepsy that is difficult to cure in children, but also can effectively reduce anxiety, depression and tiredness, this effect is most obvious in selenium-deficient people.
Selenium is closely related to human endocrine hormones, in which the amount of selenium in the human thyroid gland is higher than other tissues except for the liver and kidneys, selenium has a very important function in thyroid tissue, can regulate the metabolic balance of thyroid hormones, selenium deficiency will cause thyroid dysfunction.
The incidence of prostate disease in low areas is much higher than in high selenium areas, in the process of prostate pathological evolution, elemental cadmium plays an important role, with the growth of age and environmental influences and low selenium lead to endocrine disorders, so that the prostate gland accumulates cadmium and cause prostate hyperplasia and even tumors. Selenium has a growth-promoting effect of cadmium on the human prostate epithelium, thereby alleviating the disease.
The selenium level in the semen of male infertility patients is generally low, and the study found that the higher the selenium level in the semen, the greater the number of sperm and the stronger the motility. Human sperm cells contain a large number of non-, susceptible to the presence of oxygen free radicals in semen, inducing lipid peroxidation, thereby damaging the sperm membrane, reducing sperm motility, and even loss of function, resulting in infertility. Selenium has a powerful antioxidant effect, which scavenges excess free radicals and inhibits lipid peroxidation. Male infertility patients have low semen selenium levels, which naturally weakens the body's own clearance of oxygen free radicals present in semen and inhibition of lipid peroxidation, resulting in low sperm motility, high mortality, and infertility.
Some foods contain higher selenium, such as: seafood, edible mushrooms, meat, eggs contain more selenium than meat, per 100 grams of food, pork contains selenium 10.6 micrograms, eggs contain selenium 23.3 micrograms, duck eggs contain selenium 30.7 micrograms, goose eggs contain selenium 33.6 micrograms, ginseng contains selenium 15 micrograms, peanuts contain selenium 13.7 micrograms.
Methods of selenium supplementation
1． Artificial selenium supplementation: ingestion of artificially added various types of selenium supplement products are mainly divided into inorganic selenium and organic selenium, inorganic selenium is mainly sodium selenite, in the body selenium and vitamin E synergy, can protect the cell membrane, prevent the oxidation of unsaturated fatty acids. Trace selenium has anti-cancer effects and liver protection effects. It is mainly used for selenium deficiency patients and the prevention and treatment of endemic disease - Keshan disease, as well as selenium deficiency patients who rely on intravenous high nutrition for a long time.
Dosage: Oral, adults need to use 50 to 500 mg per month.
Children 10 to 50 mg.
Sodium selenite tablets contain 1 mg of sodium selenite per tablet ( equivalent to 457 μg of selenium ) 2 tablets each time for adults over 11 years of age and adults.
Children 2-4 years of age, take half a tablet once a day; 5 years of age, take 1 tablet each time; Side effects: Taking excessive amounts of selenium can cause poisoning, with a maximum safe daily amount of 400 μg.
Due to the high toxicity of inorganic selenium salts, it has been banned in Food and Feed in Japan in 1993, supporting the use of higher safety selenium in organic forms such as selenoproteins and amino acids, or selenium-rich agricultural and sideline products.
Compared with inorganic selenium such as sodium selenite, organic selenium has the advantages of safe consumption, non-toxic side effects, high absorption and utilization rate, and high nutritional value (such as high level of vitamins, high-quality protein, etc.). No side effects are also beneficial for absorption. It is the first choice for the ideal selenium supplement.
2, natural selenium supplementation: eat wild, natural selenium content of high natural growth of food, etc., supplemented for organic selenium, relative to inorganic selenium its toxicity has been reduced, but also need to be in accordance with the prescribed intake of scientific selenium supplementation. Naturally occurring selenium foods are healthier than inorganic selenium. The use of natural selenium supplementation is more beneficial to good health than the intake of inorganic selenium.
Some foods are high in selenium, such as: seafood, edible mushrooms, meat, poultry eggs, broccoli, purple potatoes, garlic and other foods. Nutritionists also advocate supplementing organic selenium through selenium-fortified foods, such as selenium-rich ganoderma lucidum, selenium-rich rice, selenium-rich eggs, selenium-rich mushrooms, selenium-rich tea, selenium-rich malt, selenium-rich polysaccharides, selenium yeast, etc. Selenium-rich fruit juice, selenium-rich pasture, selenium-rich milk, selenium-rich wheat, selenium-rich beer, selenium-rich biscuits and selenium-rich beef jerky, selenium-rich fruits, selenium-rich grains, selenium-rich hairy crabs.
Not excessive. Because excessive intake of selenium can lead to poisoning, hair loss, nail loss and so on. The amount of selenium in the diet in most parts of China is sufficient and safe. Selenium poisoning caused by selenium overdose seen in clinical practice is divided into acute, subacute and chronic. The main cause of poisoning is the body's direct or indirect intake and exposure to a large amount of selenium, including occupational and regional reasons, dietary habits and drug abuse. Therefore, selenium supplementation should be strict and accurate intake, and it is recommended to take selenium supplements with national certification.
Acute poisoning usually occurs after ingesting large amounts of high selenium substances, and daily intake of selenium up to 400 to 800 mg/kg body weight can lead to acute poisoning. The main manifestations are motor abnormalities and postural morbidity, dyspnea, flatulence, high fever, rapid pulse, prostration, and death due to respiratory failure. Fatal poisoning is mostly preceded by direct myocardial suppression and refractory hypotension by peripheral vasodilation. Characteristic symptoms are garlic or sour breath, vomiting, abdominal pain, restlessness, excessive salivation, and muscle cramps.
Children with acute selenium poisoning generally have dizziness, headache, weakness, drowsiness, nausea, vomiting, diarrhea, garlic odor in breath and sweat, and irritation of the upper respiratory tract and conjunctiva. In severe cases, there are manifestations of bronchitis, chills, high fever, sweating, finger tremors, and hepatomegaly. Acute selenium poisoning is characterized by hair and nail loss, rashes, peripheral neuropathy, and mottled tooth color. Laboratory tests, leukocytosis, urine selenium content is not high, after 2 to 3 days symptoms gradually improve. Patients who mistakenly take sodium selenite produce polyneurositis and myocarditis, which should be distinguished from acute selenosis to prevent misdiagnosis.
Chronic selenium poisoning is often due to a daily intake of 2400 to 3000 selenium from food, which can take up to several months before symptoms appear. Manifested by hair loss, nail loss, yellow skin coloring, bad breath, fatigue, increased caries susceptibility, depression, etc.
Generally, chronic selenium poisoning generally has dizziness, headache, fatigue and weakness, metallic taste in the mouth, nausea, vomiting, loss of appetite, diarrhea, breathing and sweat with garlic odor, and can also have hepatomegaly, abnormal liver function, autonomic dysfunction, and increased urine selenium. Long-term high selenium makes children grow long, stunted weight, rough and fragile hair, and even neurological symptoms and intelligent changes. The main features of chronic selenosis are hair loss and changes in the shape of the nails.