What is the highest source of flavonoids?

November 16, 2025 •

4 min read

According to the USDA database, dried herbs like parsley and oregano contain some of the highest concentrations of flavonoids, with total amounts far exceeding those found in most fruits and vegetables per 100 grams. This reveals the powerful potential of common pantry staples as a leading source of these beneficial plant compounds.

Quick Summary

This article examines the top dietary sources of flavonoids, detailing which spices, herbs, vegetables, fruits, and beverages offer the highest concentrations. It highlights how these potent antioxidants support overall health, explaining the importance of incorporating a diverse range of plant-based foods into your diet for maximum benefit.

Key Points

Dried Parsley is a top source: On a weight-for-weight basis, dried parsley offers one of the highest concentrations of flavonoids, particularly the flavone apigenin.
Herbs and spices are highly potent: Mexican oregano, celery seeds, and capers are other spices and herbs that contain exceptionally high levels of flavonoids per 100 grams, proving that small quantities pack a powerful punch.
Onions are rich in quercetin: The edible outer layers of onions, especially red ones, are a key dietary source of the flavonol quercetin.
Variety is crucial: Since flavonoids come in multiple subclasses, incorporating a wide range of colorful plant foods—such as berries, dark chocolate, tea, and red cabbage—is essential for a broad intake.
Not all sources are equal: While herbs may have the highest concentration, fresh vegetables and fruits are often consumed in larger volumes, contributing significantly to overall flavonoid intake.
Maximizing intake involves diverse sources: Liberally using high-flavonoid herbs and spices, choosing high-cocoa dark chocolate, and eating a wide variety of fruits and vegetables are practical ways to boost your diet.

What Are Flavonoids?

Flavonoids are a diverse group of plant chemicals, or phytonutrients, found in most fruits, vegetables, herbs, and other plant-based products like tea and cocoa. They are a class of polyphenols well-regarded for their potent antioxidant and anti-inflammatory effects within the body. These compounds help protect against cellular damage caused by unstable molecules known as free radicals, which is a major factor in the development of chronic diseases. By scavenging these free radicals, flavonoids play a protective role that contributes to cardiovascular health, cognitive function, and may help reduce the risk of certain cancers. Their health benefits are influenced by their specific structure, bioavailability, and how they are metabolized after consumption.

The Six Subclasses of Flavonoids

Flavonoids are organized into six main subclasses, with different food sources being rich in different types.

Flavonols: Found in onions, kale, broccoli, and apples. Quercetin is a prominent flavonol.
Flavanones: Abundant in citrus fruits like oranges, lemons, and grapefruits.
Flavones: Found in herbs like parsley, thyme, and celery, as well as some vegetables like bell peppers.
Isoflavones: Primarily concentrated in soy and other legumes.
Flavan-3-ols: Rich sources include green tea, black tea, and cocoa, which contain catechins and procyanidins.
Anthocyanins: These pigments create the vibrant red, purple, and blue colors in fruits and vegetables like berries, red grapes, and red cabbage.

Highest Flavonoid Sources per 100 Grams

When analyzing flavonoid content, it is crucial to look at the concentration per 100g of food, as this reveals the most potent sources. While many whole foods contribute to overall flavonoid intake, some specific herbs and spices contain extremely high levels, though they are typically consumed in smaller quantities.

The Unrivaled Potency of Herbs and Spices

According to USDA data from 2014, some dried herbs and spices are far and away the highest sources of flavonoids on a per-gram basis.

Parsley: Dried parsley is an exceptional source, particularly of the flavone apigenin, with total flavonoid content approaching 4855 mg per 100 grams.
Mexican Oregano: This herb provides a significant amount of luteolin and naringenin, with total flavonoids around 1551 mg per 100 grams.
Celery Seeds: Also a powerful source, containing high levels of the flavone luteolin.
Capers: These contain large quantities of flavonols, including quercetin and kaempferol.

Vegetables with High Flavonoid Content

Beyond herbs and spices, many everyday vegetables are rich in flavonoids and should form a core part of a healthy diet.

Onions: This is a top source of the flavonol quercetin, especially the outer layers. Red onions tend to have higher total flavonoid content than white varieties.
Kale: This dark leafy green is a excellent source of flavonols and other antioxidants.
Red Cabbage: Rich in anthocyanins, which give it its deep color.
Broccoli and Brussels Sprouts: These cruciferous vegetables contain varying levels of flavonoids and are known for their health-promoting properties.

Fruits, Beverages, and Other Top Performers

Berries: Blueberries, blackberries, and blackcurrants are excellent sources of anthocyanins and other flavonoid types.
Dark Chocolate and Cocoa: The flavan-3-ols (catechins and procyanidins) in high-cocoa-content dark chocolate make it a rich source of flavonoids.
Tea: Both green and black tea are packed with catechins.
Red Wine: The flavonoids in red wine, including anthocyanins and flavonols, come from the grape skins during fermentation.

Comparison of Key Flavonoid Sources

This table provides a snapshot comparison of selected high-flavonoid foods, highlighting the remarkable concentrations found in dried herbs versus fresh foods. Remember that while herbs are more concentrated, fresh produce is often consumed in larger portions.


Food Source	Primary Flavonoid Type	Approximate Flavonoid Content (per 100g dry weight)	Key Bioactive Compounds	Sources
Dried Parsley	Flavones	~4855 mg	Apigenin, Luteolin
Mexican Oregano	Flavones	~1551 mg	Luteolin, Naringenin
Capers	Flavonols	~493 mg	Kaempferol, Quercetin
Dried Cloves	Flavonoids (total)	~366 mg	Eugenol, Gallic Acid
Red Onion (fresh)	Flavonols	~30-45 mg	Quercetin
Dark Chocolate	Flavan-3-ols	Varies by cocoa content	Catechins, Procyanidins
Blueberries (fresh)	Anthocyanins	Varies, but high	Cyanidin, Delphinidin, Malvidin

How to Maximize Your Flavonoid Intake

Focus on Diversity and Color: Eating a wide variety of colorful fruits and vegetables is the most effective strategy. The different colors often indicate different types of flavonoids.
Use Herbs Liberally: Incorporate dried herbs like parsley, oregano, and thyme into your cooking. They are a highly concentrated source that is easy to add to most meals.
Don't Discard Onion Skins: The outer, inedible skins of onions contain a higher concentration of quercetin than the fleshy part. Consider using them to flavor soups or broths, which transfers some of the compounds.
Include High-Cocoa Dark Chocolate: Opt for dark chocolate with a high cocoa percentage to maximize your flavan-3-ol intake.
Brew Quality Tea: Green and black tea are excellent daily sources of flavan-3-ols. Consuming it without milk can increase antioxidant availability.
Cooking Considerations: Cooking can affect flavonoid content. Some studies show moderate increases in antioxidant capacity from cooking due to structural changes, while others show losses. A balanced approach involves a mix of raw and cooked flavonoid-rich foods.
Outbound Resource: For more detailed information on flavonoids and their therapeutic properties, explore this comprehensive review on the NCBI website: Important Flavonoids and Their Role as a Therapeutic Agent.

Conclusion: The Path to Flavonoid-Rich Eating

While dried parsley and Mexican oregano may hold the title for the highest flavonoid concentration on a per-gram basis, the key takeaway is the importance of a diverse and colorful diet. Incorporating a wide array of flavonoid-rich foods—from herbs and spices to berries, cocoa, and various vegetables—ensures you consume a broad spectrum of these beneficial compounds. By making simple dietary choices, such as sprinkling fresh parsley on dishes or choosing dark chocolate for a treat, you can significantly increase your flavonoid intake. Ultimately, a balanced diet featuring many plant-based sources, rather than relying on a single food, is the most effective strategy for harnessing the full health benefits of flavonoids.

Frequently Asked Questions

Dried parsley, particularly the dried leaves, is typically cited as one of the single highest sources of flavonoids, especially the apigenin compound, when measured by weight.

The effect of cooking varies by food and method. For onions, cooking can release some flavonoids, but other heat-dependent processes can also lead to some degradation. Using flavorful parts like the outer layers in broths can capture some of their flavonoid content.

Yes, dark chocolate with a high cocoa content is a very good source of flavan-3-ols, a type of flavonoid. The flavonoid level depends on the cocoa percentage and processing method.

Berries are generally excellent sources of anthocyanins. Reviews suggest that blackcurrants and blueberries often contain some of the highest concentrations of these potent compounds.

Experts generally recommend obtaining flavonoids directly from a diverse range of whole foods rather than supplements. Bioavailability and synergistic effects with other nutrients in whole foods are complex and not fully replicated in supplements.

Beyond onions, other vegetables with high flavonoid content include kale, spinach, red cabbage, broccoli, and peppers. Eating a variety of these provides a wide spectrum of flavonoid types.

Different plant foods contain different subclasses of flavonoids, each with potentially distinct health benefits. Eating a variety of sources ensures you receive a broad and diverse intake of these phytonutrients for overall health.