Selenium is a non-metallic element with the chemical symbol Se. It is located in group VI A (element No. 34) in the fourth period of the periodic table of chemical elements. It can be used as photosensitive materials, electrolytic manganese industry catalysts, essential nutrients for animals and beneficial nutrients for plants, etc. Selenium exists in two ways 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 mineral deposits; the latter is selenium combined with amino acids through biological transformation, and generally exists in the form of selenomethionine.

Selenium is divided into plant-active selenium and inorganic selenium. Inorganic selenium generally refers to sodium selenite and sodium selenate, including yeast selenium and malt selenium with large amounts of inorganic selenium residues, which are obtained from metal mineral deposits. Obtained from by-products, inorganic selenium is highly toxic and difficult to absorb, making it unsuitable for humans and animals. Plant-active selenium is formed through biotransformation and combined with amino acids, and generally exists in the form of selenomethionine. Plant-active selenium is a selenium source allowed for use by humans and animals.

Foods containing more selenium and their selenium content are as follows (micrograms/100g):

Fried white pumpkin seeds (27.03), safflower beans (19.05), tiger skin Kidney beans (9.75), flower peas (9.72), soybeans (6.16), red kidney beans (4.61), broad beans (4.29), mung beans (4.28), peanuts (3.94), northern tofu (2.62), southern tofu (1.55).

Pork kidney (kidney) (111.77), beef kidney (kidney) (70.25), duck liver (52.27), chicken liver (38.55), turkey liver (36.00), beef (lean) (10.55 ), chicken breast (10.50), pork (lean) (9.50), lamb (lean) (7.18).

Quail eggs (25.48), white eggs (16.55), brown eggs (14.98).

Chinese horseshoe crab (113.50), shrimp skin (74.43), matchmaker fish (59.75), mackerel (Squid) (57.98), Spanish mackerel (Bayu) (51.81), sea shrimp (56.41), Dace (48.10), large yellow croaker (42.57), herring (37.69), hairtail (36.57), perch (33.06), river shrimp (29.65), moray eel (25.85), etc.

Konjak essence powder (350.15), alfalfa (8.53), red cabbage moss (8.43), cabbage moss (cabbage moss, cabbage sum) (6.68), fresh dragon tooth beans (jade beans) (5.60) , garlic (purple skin) (5.54), fresh dragon beans (4.06), ladle white (vegetable) (3.40), carrot (yellow) (2.80), agaric (luokui) (2.60), edamame (green beans) ( 2.48), mulberries, pears, mangoes, etc. are relatively rich in selenium than fruits and vegetables.