Is There Tannin in Walnuts? The Comprehensive Answer

January 7, 2026 •

4 min read

Recent nutritional studies highlight that walnuts possess exceptional antioxidant activity, largely attributed to their rich content of polyphenols, which include tannins. This brings up a common question: Is there tannin in walnuts, and if so, how does this compound affect their flavor and your health?

Quick Summary

Walnuts contain tannins, concentrated in their inner skin, which contribute to a bitter, astringent taste. These compounds offer antioxidant benefits but can also affect mineral absorption. Soaking or peeling can reduce tannin levels and improve digestibility.

Key Points

Tannins are in walnuts: Yes, walnuts contain tannins, which are primarily located in the bitter-tasting papery skin covering the kernel.
Tannins offer health benefits: As a type of polyphenol, tannins provide antioxidant and anti-inflammatory effects that are beneficial for overall health.
Tannins can be anti-nutrients: These compounds can interfere with the absorption of certain minerals, such as iron and zinc, though this is not a major concern for most people with a balanced diet.
Black walnuts have more tannins: The wild Black walnut ($Juglans nigra$) contains a higher concentration of tannins compared to the more common English walnut ($Juglans regia$).
Soaking reduces tannins: Soaking walnuts overnight helps to leach out tannins, reducing their bitterness and improving digestibility for sensitive individuals.
Peeling removes most tannins: To eliminate the majority of tannins and the associated bitter taste, the papery skin can be peeled off, but this also removes a high concentration of antioxidants.

Yes, Walnuts Contain Tannins

Indeed, walnuts contain tannins, which are a class of polyphenolic compounds. These compounds are most concentrated in the thin, papery skin (the pellicle) that covers the walnut kernel. The presence of tannins is responsible for the slightly bitter, astringent taste and the drying sensation you may experience in your mouth after eating walnuts. The type of tannins found predominantly in walnuts are known as ellagitannins.

The Dual Nature of Tannins: Benefits and Considerations

While often labeled as 'antinutrients' for their ability to bind with minerals and proteins, tannins are not entirely bad. Their effect is nuanced and depends on individual gut health and dietary habits.

Potential Benefits of Tannins:

Powerful Antioxidants: Tannins are potent antioxidants that help neutralize free radicals, protecting cells from oxidative damage.
Anti-Inflammatory Properties: Through their antioxidant effects, tannins contribute to reducing inflammation, which is linked to many chronic diseases.
Improved Gut Health: The beneficial bacteria in your gut can break down ellagitannins into urolithins, bioactive compounds with antioxidant and anti-inflammatory properties.
Antimicrobial Effects: Extracts from black walnut hulls, which are high in tannins, have demonstrated antibacterial effects against common bacteria.

Potential Anti-Nutrient Effects:

Mineral Absorption: Tannins can form complexes with minerals like iron, zinc, and calcium, potentially hindering their absorption. For most people with a balanced diet, this effect is minimal and not a cause for concern. However, individuals with iron deficiency should be mindful of consuming tannin-rich foods with iron-rich meals.
Digestive Discomfort: For some sensitive individuals, the presence of tannins and other compounds like phytic acid can cause minor gastrointestinal discomfort.

English Walnuts vs. Black Walnuts

Not all walnuts are created equal when it comes to their tannin content. The two most common types are English walnuts ($Juglans regia$) and Black walnuts ($Juglans nigra$).

Comparison Table: Tannin Content and Characteristics


Feature	English Walnuts	Black Walnuts
Commonality	Most common commercially grown and consumed walnut.	Grow wild across North America and are less common commercially.
Tannin Concentration	Lower, though still significant, tannin concentration, mostly in the skin.	Higher concentration of tannins, leading to a much more pronounced astringent and earthy flavor.
Flavor Profile	Milder, with a slightly tangy and earthy profile.	Bolder, more intense, and significantly more bitter and earthy.
Health Compounds	Contains a remarkable array of polyphenols, including ellagitannins.	High in polyphenols, tannins, and the compound juglone, with potent antimicrobial effects.

How to Reduce Tannins in Walnuts

If you find the bitter taste of tannins unpleasant or are concerned about mineral absorption, there are effective ways to reduce their levels in walnuts.

Methods for Reducing Tannin Content

Soaking: This is the most common method. Soaking walnuts in water helps to leach out the bitter tannins and phytic acid.
1. Place raw walnut kernels in a bowl and cover them with water.
2. Add a pinch of sea salt (optional, as some believe it helps neutralize antinutrients).
3. Let them soak overnight (about 8-12 hours).
4. Drain the water, which will be dark with tannins.
5. Rinse the walnuts thoroughly under fresh running water.
6. The soaked walnuts can be eaten immediately or dehydrated at a low temperature to restore their crispness.
Peeling: Since the majority of tannins are concentrated in the papery skin, peeling this off after soaking can significantly reduce the bitter flavor. Research has shown that removing the skin can reduce the total phenolic content by as much as 90%. However, this also removes a substantial portion of the antioxidants. Consider your priorities: milder taste or maximum antioxidants.
Toasting: Lightly toasting walnuts can also alter the chemical composition, changing the flavor profile and potentially reducing bitterness, though soaking is more effective for direct tannin removal.

Conclusion

In conclusion, walnuts do contain tannins, which are concentrated in their outer skin and contribute to their characteristic bitter flavor. These tannins, belonging to the polyphenol family, are a double-edged sword: they provide significant antioxidant and anti-inflammatory benefits while also acting as 'antinutrients' that can inhibit mineral absorption. The impact of tannins on health is generally balanced in a varied diet, and the benefits of walnut consumption—rich in omega-3 fatty acids, protein, and other nutrients—are widely recognized. For those who are sensitive to the bitterness or concerned about mineral chelation, simple preparation methods like soaking or peeling can effectively reduce the tannin content, making walnuts more palatable and easier to digest. The choice to modify walnuts comes down to personal taste preference and individual health needs.

For more detailed nutritional information on walnuts, you can visit authoritative sources like the University of California, Davis, a leading research institution on the subject.

Frequently Asked Questions

The tannins in walnuts are primarily concentrated in the thin, papery skin (the pellicle) that surrounds the edible walnut kernel.

The bitter and astringent taste in walnuts is caused by the tannins located in the skin. The intensity of this flavor can vary depending on the freshness of the nuts and whether they are soaked or not.

Yes, soaking walnuts in water, especially overnight, is a well-known method for leaching out tannins and phytic acid, which significantly reduces the bitter taste and improves digestibility.

Tannins have both positive and negative attributes. They are potent antioxidants with anti-inflammatory effects, but they can also inhibit the absorption of some minerals. For most people, the overall benefits of eating walnuts outweigh the potential negative effects.

The tannin content varies among different nuts. Walnuts are noted for their high levels of ellagitannins, while other nuts like almonds and hazelnuts also contain tannins, though often in different concentrations and types.

To effectively reduce bitterness from tannins, it is generally recommended to soak shelled walnuts in water for at least 8 to 12 hours, and then rinse them thoroughly.

The tannins in walnuts, along with other polyphenols, offer antioxidant protection against cellular damage and may help reduce inflammation. When broken down by gut bacteria, they also produce beneficial urolithins.