"Selenium" remains unfamiliar to many. This element was discovered by Swedish chemist Jöns Jacob Berzelius in 1817 and is denoted by the symbol Se. Initially, chemists focused solely on selenium's chemical properties and its applications in industry and agriculture. Its connection to human health, however, has only been scientifically recognized over the past half-century.Scientific research confirms that selenium is linked to over 40 diseases, including cancer and hypertension. Consequently, it is hailed as the "spark of life," the "king of cancer fighters," the "guardian of the heart," and a "natural detoxifier." Below, we explore selenium's role in our health.
Primary dietary sources of selenium: Infants obtain selenium primarily from breast milk.For weaned children and adults, selenium is primarily obtained from food. Animal-based foods like liver, kidneys, and eyeballs, as well as seafood, contain higher levels of selenium. The selenium content in grains, vegetables, and fruits depends on the selenium levels in the local soil. Therefore, selenium-deficient regions can use selenium-enriched fertilizers to improve soil composition, while other areas can also cultivate selenium-rich products using such fertilizers.
Distribution of Selenium in the Body and Its Functions Selenium is primarily absorbed through the gastrointestinal tract. After absorption, it is transported via plasma to various tissues, concentrating mainly in the kidneys, liver, pancreas, pituitary gland, and hair. Muscle, bone, and blood contain relatively lower levels, while fat has the least selenium content.Within the human body, selenium exhibits antioxidant, anti-aging, anti-radiation, and antiviral properties, protects vision, and enhances immunity. It boosts the body's immune system, prevents and combats cancer; lowers blood lipids and blood pressure, preventing atherosclerosis;prevents blood clot formation and reduces myocardial infarction area; prevents fatty liver, alcoholic liver disease, and liver cancer; substitutes insulin function and activates normal pancreatic cell function; enhances local anti-infection capacity of the prostate, controlling inflammation and hyperplasia; protects vision; clears bodily waste, eliminates toxins, and neutralizes heavy metal poisoning from lead, cadmium, mercury, etc., making it an ideal natural detoxifier.
Normal selenium intake and the hazards of deficiency/excess In 1988, the Chinese Trace Elements Association and Chinese Nutrition Association announced that the daily selenium requirement for healthy adults is 50–200 micrograms. Intake below 50 micrograms daily leads to selenium deficiency and associated symptoms.Through years of research, Chinese experts have discovered that in selenium-deficient regions, the incidence rates of Keshan disease, osteochondrodysplasia, and cancer are significantly higher than in selenium-rich areas.
In 1965, Xi'an Medical College and other institutions pioneered the use of oral sodium selenite to prevent Keshan disease, achieving notable results. However, excessive selenium intake must be avoided. Studies indicate that prolonged daily consumption of selenium-rich foods or water (400–800 micrograms) can lead to selenium accumulation in the body, causing selenium poisoning.
Chronic selenium poisoning is characterized by hair loss, deformities, and liver cirrhosis. Acute selenium poisoning manifests as nausea, vomiting, hair loss, nail loss, rashes, peripheral neuropathy, mottled tooth enamel, and increased dental caries incidence.Excessive selenium often originates from industrial selenium-containing wastewater. Therefore, to eliminate selenium pollution, direct discharge of selenium-containing wastewater must be avoided to prevent environmental contamination and harm to human health.Human hair also contains a certain amount of selenium. Therefore, selenium levels in hair can reflect dietary and body selenium intake, serving as a useful indicator for assessing human selenium nutritional status. Blood selenium levels accurately reflect the actual selenium status within the human body.
Typically, adult female hair contains 0.02–3.13 μg of selenium, whole blood contains 0.03–0.32 μg, and serum contains 0.01–0.33 μg.Clinically, the severity of selenium deficiency is often diagnosed based on primary symptoms and pathological changes such as muscle atrophy and degeneration, sparse hair, thickening of limb bones and joints, and weight loss, combined with measurements of blood selenium, urinary selenium, or hair selenium.
Considerations for Selenium Supplementation When supplementing selenium, distinguish between inorganic and organic forms. Inorganic selenium, present in minerals, is insoluble in water, poorly absorbed by the body, and carries toxic side effects. Its use is now explicitly prohibited in Western countries.Inorganic selenium can be forcibly converted into soluble inorganic selenium, such as sodium selenate or sodium selenite fertilizers. By applying inorganic selenium fertilizers during plant growth, inorganic selenium is absorbed by plants and converted into organic selenium, which can then be absorbed and utilized by the human body.
Organic selenium naturally occurs in certain plants or animal livers. Through advanced extraction techniques, natural organic selenium can be produced. This form is water-soluble, highly safe, and boasts nearly 100% human absorption. Supplementing with natural organic selenium yields significant benefits, making newly launched selenium-enriched products increasingly popular.
This concludes our introduction to selenium and its role in health. We hope you've gained valuable insights. Wishing you good health this winter.