Selenium (Se) is one of the most important trace elements of the body. It is essential for the preservation of health as it participates in metabolism, in the reproductive system, is essential for the proper functioning of the thyroid gland and reduces oxidative stress and free radicals.
Selenium is a compound naturally found in many foods, both of plant and animal origin. The amount of selenium can vary considerably among foods, as it is significantly affected by the concentration of soil and food in selenium. As rich sources of selenium are considered:
- Meat, poultry, eggs and dairy products
- Bread, cereals and other enriched cereals
- Sardines, tuna, shrimps
- Brazilian nuts and sunflower seeds
Deficiency of selenium
Selenium deficiency is relatively rare and occurs in areas where there is poor selenium concentration in food and soil. Low levels of selenium have been associated with various health conditions such as hair loss, infertility, thyroid problems, heart problems (Keshan’s disease), arthropathies, aging etc. For this reason, many foods are now enriched with selenium to reduce the likelihood of shortage due to low intake.
Selenium – Properties
Hair and nails
Selenium contributes to the health of hair and nails. Low levels of selenium are associated with hair loss as well as nail brittleness.
Selenium is a key trace element for metabolism and thyroid function. Many studies have shown that people with selenium deficiency have developed problems with thyroid function. Despite the significance of selenium, it is not yet clear whether supplemental administration of selenium may contribute to the treatment or prevention of certain thyroid diseases. More research is needed to understand the effects of selenium on thyroid disease.
Selenium participates in the action of an enzyme called glutathione peroxidase, which is the antioxidant factory of cells, as it protects cellular structures from oxidative damage. According to studies, it is believed that selenium protects from aging as it prevents cellular, protein and fat oxidation, by reducing damage caused by free radicals. Selenium has synergistic action with other antioxidant molecules, such as vitamin E, helping the body to fight oxidative stress.
The biological effects of selenium are mainly expressed by selenoproteins. Some of the selenoproteins are involved in the activation, proliferation and differentiation of cells involved in the immune system. Studies have shown that selenium has immunoregulatory properties and is associated with inflammatory conditions. In addition, its powerful antioxidant properties enhance the immune system’s action by helping it to fight pathogenic microorganisms and protect cells.
Possible actions and benefits
Some studies have shown that people who consume less selenium through diet may have an increased risk of developing colon, rectal, prostate, lung, bladder, skin, esophagus and stomach cancers. However, it is not yet clear whether selenium supplements may protect from cancer of there are adverse effects. Similar results there are also for selenium and cardiovascular disease, cerebral functions and mental health. That is why more studies are needed to better understand how selenium in food and dietary supplements affects the heart and the brain.
Daily needs and dose
Daily selenium needs vary according to sex, age and stage of development. Specifically, adult men and women should receive at least 55mcg through diet, while pregnancy and breastfeeding needs are increased to 60-70mcg, respectively. In dietary supplements, elemental selenium uptake can be at 200-300 mcg daily.
What kinds of selenium supplements are available?
Selenium is available in multivitamin formulations and even as a mono-component in dietary supplements. It may exist in various forms such as selenomethionine, selenite, selenate, or as selenium-enriched yeast. Selenomethionine is the most bioavailable form, as the human body can absorb more than 90%, unlike other selenium forms that are absorbed only by 50%.
Selenium – Side effects
Increased selenium intake is toxic to the body. Acute toxicity from selenium can cause severe gastrointestinal effects, skin lesions, neurological problems, nausea, diarrhea, skin rashes, chapped teeth, fatigue and irritability.
In Vita4you you can find a great variety of selenium dietary supplements.