Tannins in Food: What They Are, Foods High in Tannins, and Kakadu Plum’s 11 Named Tannins

By Darren McArthur, Real McArthur, an Australian family business making natural products for over 25 years · Published 25 September 2026 · Last updated 30 September 2026 · Sourced from published studies

Our Kakadu plum, lab tested: 121mg of natural vitamin C in every gram, 60mg in every capsule, against an adult need of 45mg a day. Gram for gram, 240 times the vitamin C of a fresh orange.

Tannins are plant compounds that bind to proteins, which is what gives tea, red wine and unripe fruit their dry, puckering taste. They are polyphenols, and the foods highest in tannins include tea, red wine, grape skins, pomegranate, dark chocolate, walnuts and berries. In the body they act as antioxidants, and they can also bind iron from food. An Australian fruit, Kakadu plum, carries 11 named tannins, plus a twelfth, terminalagin, found nowhere else so far, and gram for gram our lab-tested Kakadu plum has 240 times the vitamin C of a fresh orange.

Tannins are one of the most studied groups of plant compounds in nutrition science — and one of the least understood by most people who consume them daily. Every cup of tea, glass of red wine, square of dark chocolate and handful of walnuts contains them. They are responsible for the dry, puckering sensation on the tongue. They are the reason unripe fruit is unpleasant and why pomegranate is marketed as an antioxidant powerhouse.

Kakadu plum contains 11 named tannin compounds, identified in a 2022 study of Northern Territory fruit, including punicalagin, the tannin pomegranate is famous for. A twelfth tannin was identified so recently that it was named in a 2024 paper, and it appears to be unique to this fruit.

Kakadu Plum Capsules — whole fruit and seed, 11 named tannins, 46 cents each →

What Tannins Are

Tannins are a family of polyphenol compounds found in plants. They are large molecules with multiple hydroxyl groups, which gives them two key properties: they bind to proteins and minerals, and they donate electrons to free radicals.

Plants produce them as a defence mechanism — against insects, fungi and animals. The astringency you feel from strong tea, unripe fruit or grape skins is tannin doing its job: binding to proteins in your saliva and causing that dry, puckering sensation.

The word comes from their oldest industrial application: tanning leather. Tannins bind to animal hides and convert them to stable, durable leather. The same binding capacity that works on leather proteins works on free radicals in biological systems — which is why tannins are strong plant antioxidants.

There are two main families:

• Condensed tannins (proanthocyanidins) — found in grape seeds, bark, berries. These are chains of flavonoid units.
• Hydrolysable tannins (ellagitannins and gallotannins) — found in pomegranate, oak, and Kakadu plum. These break down in the body into smaller active compounds including ellagic acid and gallic acid.

Kakadu plum contains hydrolysable tannins — the same family as pomegranate, which has built an entire supplement industry on a single ellagitannin called punicalagin. Kakadu plum contains punicalagin too — along with ten other named compounds.

Tannins in Wine and Tea

Tannin in wine comes mostly from grape skins, seeds and stems, and from oak barrels. It gives red wine its dry, gripping feel and helps it age; red wines are much higher in tannin than whites because the juice sits with the skins. Grape varieties with thick skins, such as cabernet sauvignon and nebbiolo, are among the most tannic, while pinot noir is lighter. White wine carries little tannin, because the juice is separated from the skins early.

Tea is one of the biggest sources of tannins in most diets. Both black and green tea carry them, and the longer tea brews, the more tannin ends up in the cup. Adding milk softens the taste because milk proteins bind some of the tannins.

What Tannins Do in the Body

In the gut, ellagitannins do two things:

First, they act as antioxidants directly. Their multiple hydroxyl groups donate electrons to free radicals, neutralising them before they can damage cells, proteins and DNA. This is the same mechanism as vitamin C and vitamin E, operating on different parts of the cell.

Second, gut bacteria metabolise them into urolithins. When ellagitannins reach the large intestine, bacteria break them into smaller compounds — ellagic acid first, then further into urolithin A, B and C. Urolithins are currently being studied for their role in mitochondrial function and cellular recycling (mitophagy). Urolithin A is also sold as a supplement, for what the body can make naturally when it has the right precursor.

The precursor — ellagic acid and ellagitannins — is exactly what Kakadu plum provides in high concentrations.

A 2024 study from the University of Queensland found that gut bacteria break Kakadu plum’s tannins into metabolites with higher antioxidant activity than the original compounds. [4]

Foods Highest in Tannins

Tannin content varies enormously between foods. The highest-tannin whole foods that most people consume include:

How much tannin a food carries depends on ripeness, processing and preparation. Unripe fruit carries more than ripe fruit, fruit skins more than peeled flesh, and tea brewed for longer more than a quick cup. That is why tannin figures for the same food vary so much between studies.

All 11 Named Tannins in Kakadu Plum, Plus Terminalagin

A 2022 study published in Frontiers in Nutrition (Phan ADT et al., PMC9372433) identified and named the following tannin compounds in Terminalia ferdinandiana fruit: [1]

1. Corilagin — 1.6 to 1.8g per 100g dried fruit. The most plentiful named tannin in the fruit. More below.
2. 3,4,6-tri-O-galloyl-glucose — about 1.0 to 1.4g per 100g dried fruit, the second most plentiful tannin. [1]
3. Ellagic acid — 0.65 to 0.73g per 100g as the free form; 2.8 to 3.4g per 100g when all bound forms are included. The starting material for urolithins.
4. Punicalagin — the dominant tannin in pomegranate, and also present in Kakadu plum.
5. Castalagin — an ellagitannin found in oak, chestnut and sweet chestnut. Also present in pomegranate. [1]
6. Geraniin — a hydrolysable tannin found in geranium and a small number of tropical fruits. Identified in Kakadu plum at measurable levels. [1]
7. Elaeocarpusin — an ellagitannin originally identified in the Elaeocarpus genus. Its presence in Kakadu plum was confirmed in the 2022 study. [1]
8. Chebulagic acid — found in terminalia species generally (the fruit of Terminalia chebula is called myrobalan). Kakadu plum is itself a Terminalia species. [1]
9. Chebulinic acid — another compound from the terminalia family, present in Kakadu plum. [1]
10. Chebulic acid — the breakdown product of chebulagic acid and chebulinic acid. [1]
11. Helioscopin B — an ellagitannin identified in the 2022 study. Less studied than corilagin but part of the same hydrolysable tannin family. [1]

Plus terminalagin — named after the tree itself (Terminalia ferdinandiana) in a 2024 paper. This compound appears to be unique to Kakadu plum — it has not been identified in any other food source. [5]

Gallic acid — the building block from which ellagic acid and most of the other tannins are formed — is one of the two main polyphenols in the fruit alongside ellagic acid. It is present alongside all of the above compounds. [1]

The Pomegranate Connection: Punicalagin

Pomegranate’s supplement reputation rests almost entirely on one compound: punicalagin. The market for pomegranate extract and juice concentrate flows largely from studies on this single tannin and its breakdown into urolithin A.

Kakadu plum carries punicalagin too, alongside ten other named tannins and terminalagin, all listed above. Pomegranate’s marketing is built on one compound. Kakadu plum contains eleven.

The Urolithin Story: Ellagic Acid

Urolithin A is sold as a supplement aimed at how cells make energy and recycle themselves. Gut bacteria make it from ellagic acid and ellagitannins, but not everyone produces much of it from diet alone: it depends on your own gut bacteria, and urolithin A supplements skip that step.

For people whose gut bacteria do convert these tannins, Kakadu plum provides the starting material in high amounts.

Corilagin — The Most Plentiful Tannin in the Fruit

Corilagin is worth highlighting separately because of its quantity. At 1.6 to 1.8 grams per 100 grams of dried fruit, it is the most abundant named tannin in the whole Kakadu plum. [1]

It belongs to the ellagitannin family, the same class as punicalagin and ellagic acid. It is also found in pomegranate, grape, and several Terminalia species. A fermentation study confirmed that corilagin remains active through 48 hours of fermentation — relevant because some processing and preservation methods degrade polyphenols before they reach the consumer. [2]

Terminalagin: Named After the Tree

Every other tannin above also exists in other plants. Terminalagin is different. It was identified and named in a 2024 paper (PubMed 41391874), named after Terminalia ferdinandiana, the scientific name of the Kakadu plum tree, and it has not been identified in any other food.

Science is still characterising this fruit: after decades of study, researchers are still finding compounds in Kakadu plum that exist nowhere else.

Are Tannins Good or Bad?

Tannins have been called antinutrients because they bind to minerals — particularly iron — reducing their absorption in the gut. This is a real, measurable effect.

But it requires context:

The binding is strongest when tannin-rich food is consumed at the same time as an iron-rich meal. Eating tannin-rich foods between meals, or with meals low in iron, produces a much smaller effect.

Vitamin C matters here: vitamin C contributes to the absorption of iron from food. Kakadu plum carries its tannins together with exceptional vitamin C in the one fruit.

Gram for gram, our lab-tested Kakadu plum has 240 times the vitamin C of a fresh orange: 60mg in every 500mg capsule, alongside the tannins. Black tea, by contrast, carries tannins with almost no vitamin C.

People with established iron deficiency should still avoid taking any concentrated tannin supplement at the same time as iron-rich foods. For most people eating a varied diet, the mineral-binding effect is small.

Tannin Sensitivity and Foods to Avoid

Some people say tannin-rich foods and drinks, especially red wine and strong tea, give them headaches or an upset stomach. Tannin sensitivity is not well studied, and red wine and tea contain other compounds that may be responsible, so it’s hard to pin on tannins alone.

People who want to cut back usually limit red wine, strong black tea, coffee, dark chocolate, pomegranate, grapes, walnuts and unripe fruit. Foods naturally very low in tannins include most dairy, eggs, meat and fish, white rice, and peeled fruit and vegetables. If you think you react to tannins, a doctor or dietitian can help you work it out.

Why Our Capsules Contain the Whole Fruit — Seed and All

Most Kakadu plum products use only the dried fruit flesh. Ours uses whole fruit powder — fruit and seed kernel together, ground to the same fine consistency throughout. The seed kernel is milled to the same standard as the fruit, producing a smooth powder with no grit. That level of processing takes more work.

We do it because the numbers are worth it. The published data proves it: the seed holds more than the fruit in 7 of 8 minerals, including:

• Zinc: 6.0mg per 100g in the seed — 10 times more than the fruit flesh (0.57mg)
• Copper: 2.5mg per 100g in the seed — 8 times more than the fruit flesh (0.30mg)
• Manganese: 9.1mg per 100g in the seed — 2.6 times more than the fruit flesh (3.5mg)
• Iron: 6.1mg per 100g in the seed — 50% more than the fruit flesh (4.0mg)

The seed also carries 32% protein, 35% fat (four-fifths unsaturated), 21% fibre, 539mg calcium, 421mg magnesium and 669mg potassium per 100g. Most Kakadu plum supplements leave the seed out. Ours keeps it, because the whole fruit, seed and all, gives you more than either part alone.

Kakadu Plum Capsules — whole fruit and seed, 46 cents each, 140 capsules →

For the full antioxidant picture — vitamin C, vitamin E, tannins, flavonoids and carotenoids together — see our antioxidant rich foods page. For vitamin E, see our vitamin E foods guide, and for how vitamin C builds collagen, what collagen does. Every nutrient in the fruit, one at a time: Kakadu plum nutrition →

Frequently Asked Questions

What are tannins?

Tannins are plant compounds from the polyphenol family that bind to proteins and minerals and donate electrons to free radicals. They give strong tea, red wine, unripe fruit and dark chocolate their dry, puckering taste, and their name comes from tanning leather.

What do tannins do to your body?

Tannins act as antioxidants, donating electrons to free radicals, and they can bind iron and other minerals from food. Gut bacteria also break some tannins down into smaller compounds called urolithins.

Are tannins good or bad for you?

Mostly good, with one catch. Tannins act as antioxidants, but they can also bind iron from a meal eaten at the same time. Vitamin C contributes to the absorption of iron from food, and for most people eating a varied diet the mineral-binding effect is small.

What food has the most tannins?

Tea, red wine and grape skins, pomegranate, dark chocolate, walnuts, chestnuts and berries are the foods and drinks highest in tannins. Among fruits, Kakadu plum stands out for variety: 11 named tannins, plus terminalagin, found only in Kakadu plum so far.

What is terminalagin?

Terminalagin is a tannin named in a 2024 paper after Terminalia ferdinandiana, the Kakadu plum tree. It appears to be unique to Kakadu plum.

What is corilagin?

Corilagin is an ellagitannin, and the most plentiful named tannin in Kakadu plum, at 1.6 to 1.8 grams per 100 grams of dried fruit. It is also found in pomegranate and grape, and it stays active through fermentation.

Do tannins survive digestion?

Partly. In a 2022 lab model of digestion, ellagic acid from Kakadu plum came through at 33% to 48%, and gut bacteria break the larger tannins into smaller compounds, including urolithins.

Why do people avoid tannins?

People avoid tannins for two main reasons: tannins can bind iron from food, which matters for anyone low in iron, and some people feel they react to tannin-rich drinks like red wine or strong tea with headaches or an upset stomach. Vitamin C with meals helps, because vitamin C contributes to the absorption of iron from food.

Do tannins cause inflammation?

There’s no good evidence that tannins in normal food amounts cause inflammation. Most research on tannins looks at them as antioxidants, and lab studies have looked at anti-inflammatory activity, but that hasn’t been proven in people.

What are the symptoms of tannin intolerance?

People who say they’re sensitive to tannins most often describe headaches, sometimes migraines, and an upset stomach after red wine or strong tea. Tannin intolerance isn’t a well-studied condition, so see a doctor if you have regular symptoms.

How do I know if I’m sensitive to tannins?

The usual way is to notice whether the same symptoms follow high-tannin foods and drinks, like red wine, strong black tea or dark chocolate, and ease when you cut back. A doctor or dietitian can help you test it properly.

What foods should I avoid if I have a tannin allergy?

People cutting back on tannins usually limit red wine, strong black tea, coffee, dark chocolate, pomegranate, grapes, walnuts and unripe fruit. A true tannin allergy is rare, so get a proper diagnosis before cutting out whole food groups.

What foods have no tannins?

Most dairy foods, eggs, meat and fish, white rice and peeled fruit and vegetables have little or no tannin. Tannins sit mainly in skins, seeds, bark, leaves and unripe fruit.

What is tannin in a wine?

Tannin in wine is the group of plant compounds from grape skins, seeds and stems, plus oak barrels, that gives red wine its dry, gripping feel. Red wines carry far more tannin than white wines because the juice sits with the skins.

Is the tannin in tea bad for you?

For most people, no. Tea is one of the biggest sources of tannins and other polyphenols in the diet. The main caution is iron: drinking strong tea with meals can reduce how much iron you absorb, so people low in iron often drink tea between meals instead.

What cancels out tannins?

Milk proteins bind some of the tannins in tea, which softens the taste. For iron, vitamin C taken with the meal helps: vitamin C contributes to the absorption of iron from food. Soaking, cooking and ripening also lower the tannin in many foods.

References

1. Phan ADT et al. Hydrolysable tannins of wild-harvested Terminalia ferdinandiana fruit at different maturity stages. Frontiers in Nutrition, 2022. PMC9372433. (The study sampled wild fruit; our Kakadu plum is farm-grown.)
2. Akter S et al. In vitro Bioaccessibility and Intestinal Absorption of Bioactive Compounds in Terminalia ferdinandiana. Frontiers in Nutrition, 2022. PMC8828953.
3. Konczak I, Zabaras D, Dunstan M et al. Health Benefits of Australian Native Foods. RIRDC (Australian Government) Pub. No. 09/133, Sept 2009.
4. Kaur P et al. Gut microbiota-mediated transformation of polyphenols from Terminalia ferdinandiana. University of Queensland, 2024.
5. Terminalagin, a New Ellagitannin from Kakadu Plum. PubMed 41391874.

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