In recent years, in supermarkets or markets, you will find more and more food products labeled with “selenium”, such as selenium-enriched rice, selenium-enriched flour, selenium-enriched eggs, selenium-enriched fruits, etc. Usually more expensive than ordinary similar products, it can be said that "the thing is 'selenium' is expensive".
You can't help but ask, what exactly is selenium? What does it do for our body?
What is selenium?
Selenium is a chemical element, the chemical symbol is Se, located in the fourth cycle of Group VI A in the periodic table of chemical elements. Selenium was discovered and named in 1817 by the Swedish chemist Yongs Jacob Bethelius from the red powder at the bottom of the lead chamber of the sulphuric acid plant. Selenium is a red or gray powder with a metallic metallic luster. The chemical nature of selenium is between metal and non-metal, and has a certain similarity with sulfur. It can be used as a semiconductor and photosensitive material, a catalyst for electrolytic manganese industry, a nutrient element essential for animals, and a beneficial nutrient for plants.
Selenium has two forms of existence in nature: inorganic selenium and plant active selenium. Inorganic selenium generally refers to sodium selenite and sodium selenate, which are obtained from by-products of metal deposits; the latter is formed by the combination of bio-transformation and amino acid, which is usually in the form of selenomethionine.
The effect of selenium on organisms
Selenium is one of the essential trace elements in animals and human body (the element with a small biomass requirement and accounting for less than 0.01% of the total weight of the organism). It is extremely important for human health and essential for maintaining normal physiological activities of the human body. . Selenium has the functions of protecting the heart, enhancing the body's antioxidant capacity, improving immunity, anti-aging, detoxification, preventing viral diseases, and enhancing fertility. It enjoys "fire of life", "longevity element", "king of anti-cancer", "The patron saint of the heart", "natural antidote" and other reputation. More than forty diseases (including cardiovascular and cerebrovascular diseases, diabetes, liver disease, prostate disease, cancer, etc.) that are known to threaten human health and life are related to selenium deficiency in humans. In turn, scientific research proves that soil is rich in selenium is longevity. An important reason is that the content of selenium in the soils of China's well-known “longevity township” in Bama, Guangxi, Hetian, Xinjiang, and Jiangjin, Chongqing is much higher than other regions. However, the amount of selenium intake must be appropriate. If it exceeds the needs of the human body, it will cause a disease similar to heavy metal poisoning. A large amount of selenium intake may even lead to chronic poisoning and death.
Unlike animals and humans, current research suggests that selenium is an essential but beneficial nutrient for plants. Appropriate amount of selenium can promote plant growth and metabolism, increase yield and quality, enhance plant antioxidant and stress resistance, alleviate the toxicity of heavy metals to plants, and play an important role in plant growth and development. However, excessive selenium has a serious toxic effect on plants, inhibiting plant growth and physiological activities, and even causing plant death. It is worth noting that the tolerance range of selenium in different plants and the symptoms of selenium poisoning may vary greatly.
Distribution of soil selenium in China
The intake of selenium in the human body is closely related to the selenium content in the soil. This is because plant food is an important source of selenium content in the human body, and the selenium content of plant foods is determined by the selenium content in the local soil.
Therefore, how to effectively use the soil selenium resources in China to meet the national demand for selenium and improve the health of the whole people is a place that government departments and scientific research need to focus on in the future.
Advocating universal selenium supplementation
When the famous nutrition expert Yu Ruomu talked about the problem of selenium deficiency in China, he stressed that human selenium deficiency is a major event that affects the health of hundreds of millions of people. It should be done like iodine supplementation. Gary Banuelos, chief expert of trace elements in the US Department of Agriculture, pointed out that selenium will become the most influential trace element in the 21st century. The significance of selenium to human health has become a broad consensus among nutrition and medical circles.
In 2005, China's selenium-removing work conference was held in the Great Hall of the People and issued an initiative to the whole society: the selenium supplement for the whole people is urgent. As a result, China has set off a selenium frenzy. 517, is the homonym of "I want selenium", so 5.17 is defined as China's National Science Selenium Day, the first National Selenium Day began on May 17, 2013.
How to scientifically supplement selenium?
Although selenium is very important, the selenium intake of human body must be appropriate, so it is very important to scientifically supplement selenium.
First of all, we must understand how much selenium is needed by the human body. In 1988, the Nutrition Society recommended that adults recommend 50-250 micrograms of selenium per day, up to 400 micrograms. Of course, the amount of selenium supplemented for different people is also different, and it needs to be taken at the recommended dosage of a doctor or a dietitian.
Then, before selenium supplementation, the cause of selenium deficiency should be ascertained. Only in this way can selenium be more accurately supplemented. There are four major reasons for the lack of selenium in modern people: (1) the amount of selenium in food, fruits and vegetables is small, and selenium is caused by insufficient intake; (2) the diet structure is unreasonable, such as partial eclipse, picky eaters, etc., affecting the body's absorption of selenium. (3) Long-term heavy drinking, blind weight loss, excessive Internet access and other bad habits can lead to selenium deficiency in the human body; (4) Middle-aged and elderly people have poor absorption capacity and consumption.
In other words, the most important thing to supplement selenium is according to the needs of the body. At present, there are many selenium-enriched products on the market, and we should follow the principle of “food supplement, supplemented by medicine” and adhere to the correct method of administration.
Author: Kunming Institute of Botany, Chinese Academy of Sciences Li Xiong