Have you ever made a sour face because you took a sip of your tea and it was rather bitter? If yes, some people might tell you it’s because of tannins in tea.

So, what is this tea tannin business? I wanted to find out, so I did some research… And the more I researched, the more I realized that the net was full of misconceptions around the topic (especially the definition of the word).

So, here I am, with a new article and hopefully clear answers to all your questions:

What is the exact definition of tannins?
How are they related to tea?
Are tannins in tea good or bad for you?

Let’s dive into it.

What Are Tannins?

Tannins are bitter-tasting organic compounds called polyphenols that can be found in a wide range of plants, including tree bark, leaves, and herbs. Tannins are part of plants’ protective system and help:

Deterring herbivores and insects
Resisting diseases and fungi (antimicrobial properties)

That is also why many unripe fruits such as persimmons have high tannin content. The astringent taste repels any animals that would want to eat the immature fruit, giving time for the seeds to be ready for germination. So tannin content decline as fruits get ripper.

Historically, they were a key ingredient in the process of tanning leather (hence the name ¨tannin¨). When tannins come into contact with animal hides, they cause them to toughen and become less porous. This makes leather more resistant to water and gives it a distinct appearance.

The tanning process typically involves soaking the hide in a solution of tannins derived from tree bark. This helps to preserve the hide and prevent it from decomposing. Tannins give leather a unique color ranging from light brown to black.

Extra info: Tannins are not the only compounds that function as protection for plants. The tea trees for example produce caffeine as a natural insecticide that prevents the leaves from being eaten. If you’re interested in knowing more, check out our previous article Caffeine in Tea here.

A teapot, a teacup full of Red tea, with some cookies and fruits on a wooden table

What Does Tannic mean in Tea?

The word ¨tannic¨ in tea describes the dry and puckering sensation you feel on your tongue when you drink a tea that has astringency. Some might perceive the tannic side of tea as an unwelcome sensation, while others enjoy the dry taste, like with a strong Red tea (known as Black tea in the West) for example.

You can find this same astringency in many other foods and beverages such as:

Red wine
Grape
Unripe fruits (banana, persimmon…)
Coffee

Tannins and Tea

Tea is Tannic But has no Tannins

As we’ve seen, tea is ¨tannic¨. So naturally, you would think tea contains tannins… But it’s not the case.

This astringent taste of tea actually comes from catechins, which are tea compounds related to tannins. Tannins and catechins are similar in the sense that they can both impart astringency to tea, and even colors (more on that later). In fact, there was a time when catechins were categorized as ¨tea tannins¨ because of their similitudes, and some people still refer to them as tannins even now.

However, while true tannins can convert hides into leather, catechins can’t be used this way. In terms of molecular weight, catechins are also much lighter than tannins and are sometimes referred to as ¨pseudo-tannins¨ or ¨tannin-like compounds¨.

A white teapot, a teacup filled with Red tea, with some cookie and apricots on a wooden table

Tannins and Oxidation

Tea polyphenols such as pseudo-tannins are partly responsible for a tea’s taste, mouth-feel and color. And different kinds of teas will contain different polyphenols with specific characteristics.

Green tea, which is a non-oxidized tea, contains a high amount of catechins (132mg/100ml of brewed Green tea) including:

Epigallocatechin-3-gallate (EGCG)
·Epicatechin-3-gallate (ECG)
Epigallocatechin (EGC)
Epicatechin (EC)
Gallocatechin (GC)

So when you drink Green tea, catechins will react in contact with your saliva, making it thinner and creating a sensation of dryness and astringency in your mouth. But in the case of oxidized teas, we find other polyphenols.

During the oxidation process of tea leaves (which basically consists in bruising the leaves to expose enzymes to oxygen), part of the catechins within the tea will turn into thearubigins and theaflavins. Those are found in abundance heavily oxidized teas like Red tea (73.4mg/100ml of brewed Red tea) and some Wu Long (Oolong) teas. While thearubigins are said to give body and a brown/red color to tea, theaflavins contribute to briskness.

Of course, there are other factors at play when it comes to tea’s characteristics such as:

The cultivar
The terroir (micro-climate)
The processing

But I find it cool how oxidation can drastically change tea leaves' taste, color, and aroma. If you want to go deeper into the topic, I invite you to read our article about Oxidation in Tea here.

Are “Tannins” in Tea Good for You?

Yes, ¨tannins¨ in tea are actually good for you! Maybe you heard before that tannins are dangerous and that you should try to avoid them in your diet. Well, that’s another misconception...

It’s true that overconsumption could result in some downsides like the hindering of metabolism and potential interference with iron absorption. But consumed in a reasonable amount, catechins, thearubigins, theaflavins and other pseudo-tannins in tea are beneficial for your health. They are actually powerful antioxidants (meaning they help protect your cells from being damaged by free radicals in your body).

For example, the catechin called EGCG found in abundance in Green tea has been extensively researched and found effective for:

Boosting your immune system
Preventing diseases (cancers, heart and neurodegenerative diseases)
Promoting oral hygiene

Extra Note: Tea is a healthy drink for sure. However, remember it’s no medicine and won’t magically cure sicknesses. And although some people suggested it, drinking tea won’t help you with the Coronavirus either.

Learn More About Tea

I hope this article cleared all the misconceptions you could have about tannins in tea. You now know that there are no real tannins in tea, just compounds with similar properties like catechins and thearubigins. You also know they can impart astringency and colors to a tea, and that they are actually good for your health.

But they are far from being the only beneficial compounds found in tea! Another one would be ¨L-theanine¨, an amino acid present in high amounts in Japanese Matcha Green tea. Another good reason to start drinking tea (if you were not already…). You can learn more about L-theanine in Matcha here.

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