Folic acid is a derivative of pteridine, which was originally isolated from the liver. Later, it was found that the green leaves of plants are very rich, so it is named folic acid. It widely exists in meat, fresh fruits and vegetables. It is a yellow crystalline powder, tasteless and odorless. Its sodium salt is easily soluble in water, insoluble in alcohol, ether and other organic solvents, insoluble in cold water but slightly soluble in hot water. It is unstable in acidic solution and easily damaged by light.

Also known as "vitamin Bc" and "vitamin M". A type of B vitamins. Yellow or orange flaky or needle-like crystals, odorless and tasteless, heated to about 250 ° C, the color gradually darkens, and finally becomes a black jelly. Anti-anemia drug, the content in tea reaches 50～70μg/100g, which can promote the formation of normal red blood cells. In the metabolism of tea tree, it is involved in the transmission of methyl groups.

It also participates in the synthesis of amino acids and nucleic acids in the body, and promotes the production of red blood cells together with vitamin B12. For all kinds of megaloblastic anemia, especially for pregnant women and infants with megaloblastic anemia. [4] Human intestinal bacteria can synthesize folic acid, so it is generally not easy to be deficient. Folic acid deficiency can be caused by malabsorption, abnormal metabolism, or long-term use of intestinal antibacterial drugs. In addition, folic acid is also widely found in animal and plant foods, which are rich in: offal, eggs, fish, pears, broad beans, beets, spinach, cauliflower, celery, lettuce, citrus, nuts and soybean foods. When the daily intake of folic acid in the human body is maintained at 3.1 μg/kg per day, there can be an appropriate amount of folic acid reserves in the body; the total daily intake of folic acid for pregnant women should be greater than 350 μg; the safe intake of infants is similar to that of adults in terms of kg body weight. That is, 3.6μg/kg per day can meet the needs of growth and maintenance of normal blood.