There are no dangers of tannic acid in tea because, contrary to popular belief, tea does not contain tannic acid, according to RateTea. Tea does, however, contain tannins, a group of plant-derived chemicals that give tea its body and bitter flavor.
The tannins in black tea are called thearubigins, which are formed when catechins from the original tea leaves are oxidized during processing, explains RateTea. These thearubigins are what give black tea its bitter, astringent flavor. The tannins present in tea may have both positive and negative affects on human health. Tannins can interfere with iron absorption and may affect protein digestibility. However, tannins are antioxidants that have anti-microbial, anti-mutagenic, and anti-carcinogenic properties.
Tannic acid is a chemical compound extracted from Chinese gallnuts, states Lvyin Biotech. Beer brewers use it to clarify their beer, and wine makers use it as a taste stabilizer. Some soft drinks and juices also contain tannins. Tannic acid is safe for human consumption in the amounts found in foods, notes WebMD. In large amounts, tannic acid can cause irritation to the stomach and bowels, as well as liver damage. There is a possible association between throat and nose cancer and the regular consumption of herbs that contain high amounts of tannic acid.