Tannins in Tea: What They Are and Why They Matter

What Are Tannins?

Tannins are compounds called polyphenols and are present in most organic matter, including leaves and wood. Tannins give the tea its astringency. Teas that are more bitter tend to have more tannins.  Plants produce them as a natural defense against pests.

When it comes to tea, when the caffeine acts as a stimulant, tannins balance it with the calming effect. When you add boiled water in tea leaves, it takes around two minutes to draw out the caffeine. After five minutes, tannins will come out from the tea leaves and will minimize the effects of the caffeine. As a result, you can enjoy a calming and relaxing tea.

Effects of Tannins on the Body

They have both positive and negative effects on the body. 

Benefits of Tannins

1. Tannins are anti-carcinogenic

Thanks to its anti-oxidizing nature, tannins not only prevent the formation of cancerous cells, but also counteracts the effect of other cancerous elements in the body.

2. Tannins are anti-mutagenic

Genetic mutation is now more common than ever due to processed foods, as well as excessive use of fertilizers and pesticides. Tannins prevent the mutation of DNA and the genetic makeup of a person.

3. Tannin promotes cardiac health

Tannins are comprised of favonoids and procyanidins. Procyanidins are a type of polyphenols which improve the function of blood vessels, improve blood flow and prevent heart diseases. Flavonoids suppress the production of peptides in the body, which can harden the arteries and hinder blood circulation.

4. Tannin helps with digestion

The anti-oxidizing nature of tannins help with digestion, preventing diarrhea and improving metabolism.

5. Tannin is good for oral hygiene

As tannins are anit-septic, it flights against bacteria in the mouth that can lead to cavities. 

Negative Effects of Tannins

Although largely useful to the body, tannins also have negative effects. They are often anti-nutritional and can hinder digestion and metabolism, unlike polyphenols. Tannins can also help obstruct the blood’s absorption of iron, which may lead to many health problems.

Highly tannic tea can lead to jaw pain, as the bitterness and astringency of tannins cause a rapid increase in saliva secretion from the salivary glands. 

1. Reduced iron absorption

One of the biggest concerns with tannins is their potential ability to hinder iron absorption. In the digestive tract, tannins can easily bind with iron present in plant-based foods, making it unavailable for absorption. Research indicates that this effect is not likely to cause significant harm in people with healthy iron levels, but it could be problematic for those with iron deficiency.

2. May cause nausea

The high levels of tannins in tea may lead to nausea if you drink tea on an empty stomach. Since green tea has the highest amounts of tannins, this is why it is not recommended to drink before a meal. The traditions of tea addressed this challenge—you can avoid this effect by having your morning cup of tea with some food or adding a splash of milk. Proteins and carbohydrates from food can bind with some of the tannins, minimizing their ability to irritate your digestive tract.

Different Tannin Levels in Tea Varietals

Tannins are released after organic matter is broken down and so the more the tea leaves are oxidized, the more tannin is released. This is why black and green teas have higher levels of tannins.

Teas with high levels of tannins have a bitter taste accompanied by strong astringency, seen especially in green and black tea. The tannins found in tea are thearubigins, most prominently theaflavins. When the anti-oxidising agents such as catechin in the tea become oxidised, theaflavins are produced. 


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