Tea comes in a wide variety of flavors and styles, but tea tannins are found in all types of tea. Tannins are part of a naturally occurring class of molecules called “polyphenols,” otherwise known as “catechins.” The bitter taste experienced by some people after drinking tea is caused by the tannins. Due to their astringency, the tannins in tea can also create a dry, puckering sensation in a person’s mouth.
Tea tannins are also responsible for a tea’s brownish color. Darker teas generally have a higher concentration of tea tannins than lighter teas. For the most part, “true” teas, such as green tea, oolong, and black tea, have higher amounts of tannins than herbal teas. The concentration of tannins in a cup of tea also increases the longer the tea is allowed to steep. Thus, if a cup of tea steeps too long, the person drinking it might find it to have an excessively piquant or bitter taste.
The tannins contained in tea have often been confused with tannic acid, a chemical substance used to tan animal hides. This is a misconception. While tea tannins belong to the same class of chemicals as tannic acid, they are not the same. The types of tannins found in tea are also found in other foods, such as pomegranates, cranberries, cocoa, and red wine.
When consumed in moderation, tea tannins are considered to have certain health benefits. For instance, the tannins found in tea are believed to fight particular types of bacteria found in a person’s mouth, thus preventing bad breath and cavities. Tea tannins are also believed to have a calming, relaxing effect on some individuals, which can counteract the nervousness or jittery feeling sometimes caused by the caffeine present in certain types of tea.
Studies have suggested that the tannins found in tea, when consumed in large quantities, can interfere with a person’s absorption of plant-based iron. Consequently, individuals who suffer from low iron, or who do not obtain iron from meat-based sources, are advised to limit tea intake to no more than four cups per day. If an individual has concerns regarding low iron levels, it is also recommended that he or she not consume tea within an hour before or after eating a meal.
Many individuals believe that tea can help combat the common cold and other such illnesses. Some studies indicate that there might be a verifiable basis for that belief. The interference of tea tannins with iron absorption might prevent certain strains of illness-causing bacteria from absorbing the iron needed to thrive. This would effectively starve the bacteria and thus help a person’s immune system to fight off the illness.