Tannins are a broad class of compounds that is present in tea, red wine, cocoa, chocolates, coffee, some herbal preparations, grapes and certain fruits like blackberries and cranberries.
Their properties are well remarkable, but not completely understood. Most of the tannins fight cavities, diarrhea, and some even protect heart diseases and cancer. They disable bacteria in the mouth, which inhibits plaque formation. Tooth decay is also prevented. But they stain teeth.

Gathering property of tannin:
Their power mainly comes from the property of astringency. It is the kind of dry, tightening and wrinkling feeling in the mouth. It is often felt while eating fruits like berries. They attach to the proteins in the saliva, creating a rough, sensation of the mouth, resembling ‘sandpaper’.
The tannin compounds that are present in some plants, provides them protection against predation. This also makes them to act as pesticides and to regulate the growth of plants. The feeling inside our mouth, on consumption of improperly ripened fruits, is also because of tannins.
Tannins also have the ability to trap some minerals, including iron- especially the iron in plant foods. So it is better to drink tea along with food, to limit the absorption of iron.
The addition of milk or lemon to tea also helps to reduce the effect of tannins. The tannins bind to anything that is added to it. It is also better to drink tea between meals.

Healing property:
The term tannin often confuses people, as there are individual tannins which vary greatly.
1. Most of them are polyphenols, whereas, some others are antioxidants.
2. Antioxidants, protects from heart diseases.
3. Prevents cancer by preventing cellular damage.
4. Polyphenols are examined for their potential health benefits.
5. Polyphenols in grapes are called resveratrol, in green and black tea, it is catechin.

Remedy by nature:
Since the tannins are well known for their astringent property, they had been used as a base for several herbal treatments. They may be mostly used in the form of tea.
Certain health experts recommend the use of some tannin- containing herbs to keep away certain everyday ailments. Some of them are;
1. Bayberry:
        a. Commonly seen as shrubs or small trees.
        b. Roots are rich in nitrogen fixing bacteria.
        c. Fruit is usually coated with wax.
        d. Used for the spicing of beer.
        e. Rich in tannins and can be used to stop diarrhea, nausea, and treat inflammation of intestine.
2. Blackberry:
        a. Small aggregate fruit with small drupelets (fleshy part surrounding a shell) associated with it.
        b. They are rich in tannins, dietary fiber, vitamin C and K.
        c. It promotes good bowel movement, stops bleeding from small cuts, and reduce diarrhea.
3. Raspberry:
        a. Rich flavored, aggregate fruit.
        b. Consists of a juicy pulp and a central seed.
        c. Contains catechins (tannins), manganese, vitamin K, etc.
        d. Also have antioxidants, flavanoids and phenols.
        e. They help to overcome morning sickness in pregnant women, and also stops diarrhea.
4. Sage:
        a. A shrub with woody stem, gray leaves and purple flowers.
        b. Used in medicines and to improve flavor.
        c. Used in making herbal tea.
        d. Soothes bleeding gums, sore throat and respiratory ailments like asthma.