Tannins are found in a wide range of everyday foods and drinks, from tea and red wine to nuts, berries, beans, and certain fruits like persimmons and pomegranates. These plant compounds are responsible for the dry, puckering sensation you get from a strong cup of black tea or an unripe banana. If you’re trying to identify which foods are high in tannins, whether to seek them out for their antioxidant benefits or limit them because of iron absorption concerns, here’s a thorough breakdown.
Tea, Coffee, and Wine
Beverages are some of the most concentrated everyday sources of tannins. Black tea leads the pack among teas, with tannin concentrations ranging from 27 to 55 percent of its dry weight. Green tea is considerably lower at 13 to 21 percent, and oolong tea falls in between at 18 to 41 percent. Coffee contains tannins as well, though generally less than black tea per serving.
Red wine is another major source. The tannin concentration in red wine typically ranges from 500 to 1,500 mg per liter, depending on the grape variety and how long the wine has aged. These tannins come primarily from grape skins, seeds, and stems. Because red winemaking leaves the skins in contact with the juice for an extended period, red wines are significantly more tannic than whites or rosés, where the skins are removed early.
Fruit juices can be surprisingly high in tannins too. Pear juice ranges from 1,450 to 4,060 mg per liter depending on the variety and ripeness. Tart cherry juice contains around 1,255 mg per liter, and wild blueberry juice comes in at roughly 1,072 mg per liter.
Fruits With High Tannin Levels
Among whole fruits, persimmons are one of the richest sources. Unripe persimmons contain roughly 4.7 to 5.0 grams of tannins per kilogram of dry weight, which is why biting into one before it’s fully ripe produces an intensely astringent, mouth-drying sensation. Pomegranates are also notably high, with condensed tannin levels between 63 and 140 mg per gram of dry weight, concentrated in the rind and membranes surrounding the seeds.
Grapes pack their tannins into the seeds, where concentrations can reach up to 241 mg per gram of dry weight. Apples contain about 16.5 mg per gram, with tannins concentrated in the skin. Berries like blueberries, cranberries, and blackberries all contribute meaningful amounts as well.
One important detail: tannin levels drop as fruit ripens. During ripening, tannin molecules link together into larger chains that no longer dissolve in your saliva, which is why they stop producing that astringent taste. This is the reason a ripe banana tastes smooth and sweet while a green one leaves a chalky feeling in your mouth. The tannins are still technically present, but in a form your taste buds can’t detect.
Nuts and Legumes
Nuts are among the most tannin-dense foods by weight. Hazelnuts top the list with condensed tannin levels around 1,261 mg per gram of dry weight, followed by almonds at roughly 776 mg per gram. In both cases, tannins are concentrated in the thin brown skin surrounding the nut. Peeling or blanching almonds, for example, removes most of their tannin content. Acorns, though not a common snack in most Western diets, contain 2.4 to 5.2 percent tannins by dry weight, which is why they’ve historically required extensive soaking before eating.
Legumes are another significant source. Fava beans contain about 685 mg per 100 grams of dry weight, chickpeas around 488 mg, black-eyed peas roughly 391 mg, and soybeans about 226 mg. Like nuts, legumes carry most of their tannins in the seed coat, the outer skin that softens and sometimes slips off during cooking.
How Cooking Reduces Tannins
Because tannins are water-soluble and sit mainly in outer layers like skins and seed coats, simple preparation methods can strip a large portion of them away. Soaking dried beans in water for 24 hours before cooking leaches tannins into the soaking water, which you then discard. Boiling reduces tannin content further. Studies on kidney beans have shown that soaking followed by boiling or pressure cooking causes a significant drop in tannins. In asparagus beans, boiling alone cut tannin levels by 49 percent. Across different varieties of common beans, cooking reduced tannins by anywhere from 20 to 81 percent depending on the variety and method.
Atmospheric boiling and steaming (cooking at normal pressure in an open or covered pot) tend to remove more tannins than pressure cooking, likely because the longer cooking times allow more leaching into the water. Fermentation also breaks down tannins, which is one reason fermented soy products like tempeh and miso are easier to digest than whole soybeans.
Why Tannins Matter for Iron Absorption
The main practical concern with tannins is their effect on iron absorption. Tannins bind to non-heme iron (the type found in plant foods, eggs, and fortified grains) in your digestive tract, forming clumps your body can’t absorb. The degree of interference depends on how much you consume and what else is in the meal.
Single-meal studies paint a wide range. Drinking tea or coffee with a meal can reduce iron absorption by 60 to 90 percent in some experiments, though average real-world reductions tend to be more modest, in the range of 3 to 27 percent. Consuming tannin-rich foods between meals rather than during them largely sidesteps the issue. Pairing high-tannin foods with vitamin C also helps counteract the binding effect.
This is primarily a concern for people who are already at risk for iron deficiency, including those who menstruate heavily, follow a plant-based diet, or have conditions that impair iron absorption. For most people eating a varied diet, the tannins in everyday foods and drinks don’t cause problems.
Quick Reference by Food Group
- Beverages: Black tea, green tea, oolong tea, coffee, red wine, pear juice, tart cherry juice, wild blueberry juice
- Fruits: Persimmons, pomegranates, grapes (especially seeds and skins), apples, blueberries, cranberries, unripe bananas
- Nuts: Hazelnuts, almonds, pecans, walnuts, acorns
- Legumes: Fava beans, chickpeas, black-eyed peas, soybeans, kidney beans
- Other: Dark chocolate, cinnamon, cloves
Tannins act as potent antioxidants, which is part of the reason foods like berries, tea, and red wine are often highlighted in discussions about plant-based nutrition. They also have antimicrobial and anti-inflammatory properties. For most people, the tannins in a normal diet are a net positive. The key is being aware of when and how you consume them if iron status is something you’re managing.