What Food Has the Highest Level of Quercetin?

November 21, 2025 •

3 min read

Multiple studies show that quercetin, a potent flavonoid, offers numerous health benefits, including antioxidant and anti-inflammatory effects. So, what food has the highest level of quercetin? The tiny, flavorful flower buds known as capers contain the highest concentration of this antioxidant, offering a significant boost in a single serving.

Quick Summary

This article reveals that capers are the most concentrated dietary source of quercetin. It also lists other powerful quercetin-rich foods and explains how cooking methods and food preparation can impact quercetin levels and bioavailability. A comparative table highlights the content found in various common items.

Key Points

Capers are the highest source: The small flower buds contain the most concentrated amount of quercetin, with some pickled capers having over 230mg per 100g.
Onions are a rich vegetable source: Raw red onions are a top vegetable source, especially the outermost layers which contain the highest concentration.
Berries and apples are strong contenders: Berries like aronia and cranberries, and apples eaten with their skin, offer substantial amounts of quercetin.
Cooking affects content: High heat and boiling can degrade quercetin, causing it to leach out into cooking water. To preserve content, eat foods raw or lightly steamed.
Bioavailability depends on factors: Quercetin's absorption can be influenced by the food matrix and whether it's consumed with fats. Different forms, like glycosides from onions, may have higher absorption rates.
Diverse intake is key: To maximize health benefits, incorporate a wide variety of quercetin-rich foods into your diet rather than relying on a single source.

Capers Top the Charts for Quercetin Content

When considering dietary sources of the flavonoid quercetin, many people think of foods like apples and onions. While these are indeed good sources, one food stands head and shoulders above the rest in terms of concentration: capers. Specifically, pickled capers contain an astonishing amount, with some reports showing levels as high as 233.8 mg per 100 grams. This makes the small, tangy flower bud a super-concentrated source of this powerful antioxidant.

Why Quercetin is a Valuable Nutrient

Quercetin is a plant pigment, or flavonoid, with numerous potential health benefits, including antioxidant and anti-inflammatory properties. It is thought to protect against oxidative stress, which can lead to chronic diseases like cardiovascular problems, some cancers, and neurodegenerative disorders. It's also linked to improved immune function and the regulation of allergic responses. While the average daily dietary intake can be quite low, focusing on foods rich in this compound can help increase your consumption significantly.

Other Significant Food Sources of Quercetin

While capers are the clear winner for concentration, a variety of other delicious and common foods can contribute to your overall quercetin intake. Consuming a diverse mix of fruits and vegetables is the best strategy for maximizing your body's absorption of this nutrient, as the compounds often work synergistically.

Fruits and Berries:

Berries: Aronia berries, lingonberries, cranberries, and blueberries are all excellent sources.
Apples: Particularly when eaten with the skin on, apples provide a good dose of quercetin.
Grapes: Red grapes contain more quercetin than white varieties.
Cherries: A sweet and easy way to add more quercetin to your diet.

Vegetables and Herbs:

Onions: Red onions are among the richest vegetable sources, especially the outer layers.
Kale: This popular leafy green is a powerhouse of nutrients, including quercetin.
Broccoli: A valuable cruciferous vegetable with a notable quercetin content.
Asparagus: A serving of cooked asparagus provides a healthy amount of quercetin.

Beverages and Other Items:

Green Tea: A common and accessible source, though with lower concentrations compared to food sources.
Black Tea: Also contains quercetin, though less than green tea.
Cocoa Powder: A less obvious but still valuable source of this antioxidant.
Buckwheat: A gluten-free seed that is rich in rutin, a type of quercetin glycoside.

Maximizing Quercetin from Your Food

The bioavailability of quercetin can be affected by food processing, storage, and preparation. Here are a few tips to help you get the most from your meals:

Minimize Heat Exposure: High heat and prolonged boiling can significantly reduce the quercetin content in vegetables, as the compound can leach into the cooking water. Steaming or light sautéing is preferable.
Eat the Skin: A large portion of quercetin is concentrated in the outer layers and skins of fruits and vegetables like apples and onions. Avoiding peeling can drastically increase your intake.
Eat Raw When Possible: For foods like red onions and capers, consuming them raw is the best way to preserve their quercetin content.

A Comparison of High-Quercetin Foods (mg/100g)


Food Source	Approximate Quercetin Content (mg/100g)	Notes
Capers	234	The most concentrated source.
Ancho Pepper	27.6	A surprisingly high amount for a spice.
Red Onions (raw)	22–39	Highest among common vegetables, especially in outer layers.
Cocoa Powder	20	A pleasant source for chocolate lovers.
Cranberries	14–15	Excellent berry source, often found in sauces and juices.
Raw Kale	7.7	A nutrient-dense leafy green.
Cooked Asparagus	7.6	Levels slightly increase upon cooking.
Blueberries	5.0	A classic superfood with decent levels.
Apples (with skin)	4.4	The peel contains the majority of the quercetin.
Raw Broccoli	3.2	A solid everyday source.

Conclusion: Capers are the Quercetin Champion

While a variety of plants offer quercetin, the undisputed champion for concentration is the caper. Adding these small but mighty buds to your diet can provide a powerful dose of this beneficial flavonoid. However, since bioavailability is also important, incorporating a diverse range of fresh and lightly cooked produce like red onions, kale, and berries is the most effective approach for a sustained and healthy intake. By focusing on whole foods and smart preparation, you can easily enhance your dietary quercetin and support your overall well-being. For more detailed information on flavonoids and their health impacts, consult authoritative sources on nutrition and food chemistry, such as the National Institutes of Health.

Frequently Asked Questions

The single highest food source of quercetin is capers, which can contain exceptionally high concentrations, often exceeding 200 mg per 100 grams, making them far more potent than other common sources.

Red onions typically contain the highest levels of quercetin among onion varieties. The concentration is particularly high in the outer, colored layers.

Cooking methods that use high heat or boiling can significantly reduce quercetin levels. Boiling is particularly detrimental, as quercetin can leach into the cooking water.

Yes, it matters significantly. A substantial amount of an apple's quercetin is concentrated in its skin, so eating apples with the skin on is the best way to maximize your intake.

Aside from onions, good vegetable sources of quercetin include kale, broccoli, and asparagus. Incorporating these into your diet regularly can help boost your overall consumption.

Pairing quercetin-rich foods with healthy fats, such as olive oil in a salad dressing, can help improve absorption, as can eating certain foods, like onions, which contain more easily absorbed forms.

Concentration can increase with dehydration. However, the final content is highly dependent on processing. Freeze-dried or mildly processed foods may retain more, while high-heat drying can cause losses.