Catechins: What They Are and Where They Come From

Catechins are flavan-3-ols, which are a type of polyphenol found primarily in green tea and cocoa. When you pour a cup of green tea, you're getting a specific blend of these compounds. I've noticed that most people think of them as a single thing, but they're actually a complex group of molecules.

Green tea and black tea both come from the same plant, Camellia sinensis, but they're not just different amounts of catechins. Instead, processing changes the compounds. Heating the leaves quickly halts oxidation, keeping the catechins intact in green tea, while oxidation transforms them into theaflavins and thearubigins in black tea. It's about the chemistry of the leaf.

What a catechin actually is

Catechins sit among the flavan-3-ols, which are a specific subclass of flavonoids. These flavonoids are themselves a type of polyphenol. I've found that categorizing these compounds can feel like a nesting doll of chemistry, but it helps to know the hierarchy of what you're actually eating.

When you pour a cup of green tea, you're consuming four main catechins: EGCG, EGC, ECG, and EC. Of these, EGCG is the most abundant. While I was shopping for green tea, I realized that these four compounds are very close relatives rather than completely separate things.

The complexity here is that these catechins are poorly absorbed in their original form. Your gut bacteria change them before they reach your bloodstream. This means the chemistry in your mug isn't a direct mirror of what happens inside your body, which is a nuance most marketing ignores.

You should think of catechins as a dynamic group of compounds rather than a single magical ingredient. Because they're transformed by your body, the focus should be on the diversity of the sources. Instead of looking for one specific catechin, look for the variety of sources you find in your pantry.

Where they actually come from

You can find them in green tea, cocoa, apples, dark grapes, and legumes. When I look for these in my kitchen, I see them in a cup of oolong tea or a handful of dark grapes. These are the primary sources for the catechins you're looking for.

The amount of catechins in green tea depends on how you brew it. If you heat the leaves soon after picking, you keep most of the original compounds. This is why green tea keeps its catechins while black tea loses them to oxidation.

Cocoa is a source, but Dutch-processed cocoa powder carries fewer than natural cocoa powder. This happens because Dutch-processing costs the cocoa some of its catechins. I know that's a letdown for people who want the simplest way to buy the best cocoa.

Coffee belongs to a different polyphenol family. It doesn't belong on a catechin list. You can see how different sources compare in the table below. This helps you understand what are catechins and where they come from in your diet.

What oxidation turns them into

Oxidation turns catechins into new polyphenols called theaflavins and thearubigins. When you pour hot water over black tea leaves, the oxygen in the air reacts with the tea's chemistry. This process changes the chemical structure of the catechins, creating the dark color you see in your mug.

Every true tea comes from the same plant, Camellia sinensis. Because they all share one source, the difference between white, green, oolong, and black tea lies in how the leaves are processed. You can see this on a shelf in a grocery store when you compare the different bags.

Green tea is heated soon after picking to halt oxidation, which keeps most of its original catechins. Oolong tea sits in the middle of the oxidation scale, while black tea undergoes the most change. These aren't just different types of tea; they're different stages of the same plant's chemistry.

You should think of these as different chemical profiles rather than just different flavors. While black tea has theaflavins, green tea retains its catechins. This means your cup of tea depends entirely on how the farmer processed the leaf. It changes what you actually drink.

What happens after you drink it

When you drink a cup of green tea, catechins aren't immediately available for your body to use. They're poorly absorbed in their original form. This means that the compound you see on a leaf label might not be the same one your body ends up with.

Your gut bacteria play a major role here. They change the catechins before they reach your bloodstream. This process means that the chemistry of your digestion is just as important as the tea you choose to brew in your kitchen.

A concentrated green tea extract sold as a supplement is a different proposition from a brewed cup. The dose is far higher in the extract. If you're considering a supplement, you should talk to your doctor, physician or pharmacist.

The evidence says that the way you eat and drink matters because of how these compounds move through your body. You should think of catechins as a dynamic process involving your unique gut health. It isn't a simple one-way street.

What we still don't know

I don't know exactly how much of a catechin reaches your blood from a single cup of green tea because your gut bacteria change them before they do. This means the amount you actually absorb depends on your unique microbiome. It isn't a simple calculation of what is in the cup.

You also have to consider that a cup of tea carries many compounds at the same time. You aren't just drinking a single isolated catechin; you're drinking a complex mixture of caffeine and L-theanine. It's hard to tell which specific compound is doing the work.

Common questions about catechins

What foods are highest in catechins?

Green tea and matcha are the primary sources of catechins in the plant world. I found that cocoa and apples, particularly the skin, also carry these compounds. While legumes are the only vegetables in the USDA database with catechins, coffee doesn't contain them.

What happens if I drink 1 cup of green tea every day?

A daily cup of green tea delivers catechins alongside caffeine and L-theanine. These three components work together in the cup, but they aren't all polyphenols. I want to know what is in the cup rather than what it does to a person.

What drink has the most catechins?

Matcha and green tea are the drinks with the highest concentrations of catechins. Because matcha is whole green tea leaf ground to powder, the drinker consumes the leaf rather than an infusion. This difference in preparation makes a significant difference in the amount of catechins you drink.

What is catechin good for?

Catechins are flavan-3-ols, a subclass of flavonoids and polyphenols. I want to know what the evidence shows, and the evidence for their effects is listed on the evidence page. You can find the primary sources for these claims on the evidence page.

Does black tea have catechins?

Black tea contains theaflavins and thearubigins rather than original catechins. This happens because the oxidation process converts the catechins into these new polyphenols. These new compounds give black tea its characteristic color and flavor.

How do you pronounce catechins?

Catechs is pronounced CAT-uh-kins, with the stress on the first syllable. I want to know how to say it correctly without sounding like a chemist. It's a bit of a mouthful, but it's easier to say once you hear it.