Quercetin is found in a wide range of fruits, vegetables, herbs, and teas. It’s one of the most common plant pigments in the human diet, responsible for deep reds, yellows, and greens in produce. Most people get between 5 and 40 milligrams a day from food, but a diet heavy in fruits and vegetables can push that to 500 milligrams daily. The richest sources may surprise you.
Herbs With the Highest Concentrations
Fresh herbs top every quercetin database by a wide margin. Lovage leads at 170 milligrams per 100 grams of fresh weight, more than double the next highest source. Fresh dill follows at about 55 mg, fresh fennel leaves at 47 mg, and fresh angelica at around 42 mg. Dried Mexican oregano also clocks in at 42 mg per 100 grams.
These numbers are striking, but context matters. You rarely eat 100 grams of fresh lovage or dill in one sitting. A generous handful of fresh herbs in a salad or soup might weigh 10 to 15 grams, delivering roughly 8 to 25 mg of quercetin depending on the herb. Still, regularly cooking with fresh herbs is one of the simplest ways to boost your intake.
Capers Are a Standout
Raw capers contain about 234 mg of quercetin per 100 grams, making them the single most concentrated common food source in the USDA flavonoid database. Even canned capers, which lose some during processing, still deliver around 173 mg per 100 grams. A tablespoon of capers weighs roughly 9 grams, so sprinkling them on a dish adds about 15 to 21 mg of quercetin with almost no effort.
Onions, Especially Red and Yellow
Onions are the most-studied quercetin source, largely because people eat them in meaningful quantities. Yellow and red onions contain between 54 and 286 mg per kilogram of fresh weight (roughly 5 to 29 mg per 100 grams), with some yellow varieties scoring highest. White onions contain only trace amounts.
The outer layers and skin hold the highest concentrations. Research from the American Society for Horticultural Science found that whole-onion analyses consistently show higher quercetin levels than analyses of just the edible inner flesh, which is what most people actually eat. So if you peel away several layers, you’re discarding a meaningful share of the quercetin. The dry papery skin itself isn’t edible, but keeping the first fleshy layer beneath it helps.
Apples and Other Fruits
Apples are probably the most commonly eaten quercetin source worldwide. The catch: nearly all of the quercetin sits in the peel. Research published in the Journal of Agricultural and Food Chemistry confirmed that flavonols (the class quercetin belongs to) are found exclusively in apple skin, not the flesh. Peeling an apple removes essentially all of its quercetin.
Other fruits with notable quercetin levels include black elderberries (about 42 mg per 100 grams), cranberries, blueberries, and cherries. Citrus fruits contain relatively little. Berries in general are reliable sources, though their concentrations vary with ripeness, growing conditions, and variety.
Leafy Greens and Vegetables
Red lettuce delivers a surprisingly high 40 mg per 100 grams, putting it in the same range as elderberries and dried oregano. Pak choy (bok choy) comes in at about 39 mg per 100 grams. Other notable vegetable sources include broccoli, kale, and green beans, though at lower concentrations.
Because you can easily eat 100 to 200 grams of leafy greens in a salad, these foods often contribute more total quercetin to your diet than the ultra-concentrated herbs you only use in small pinches.
Tea as a Daily Source
Brewed green tea contains about 2.5 mg of quercetin per 100 grams (roughly half a cup). Black tea is similar at about 2 mg per 100 grams, and oolong comes in slightly lower at 1.3 mg. These numbers sound small, but a few cups of tea per day adds up to 10 to 15 mg without any special effort. Interestingly, decaffeinated versions of both green and black tea contain slightly more quercetin than their caffeinated counterparts, likely due to concentration effects during processing.
How Cooking Affects Quercetin Levels
Not all cooking methods are equal when it comes to preserving quercetin. Research on onions found that baking and sautéing actually increased quercetin concentration by 7 to 25 percent, likely because water evaporates and the compound becomes more concentrated in the remaining tissue. Boiling, on the other hand, decreased levels by about 18 percent, as quercetin leaches into the cooking water. Even so, a five-minute boil still retained just over 80 percent of the original flavonol content.
The practical takeaway: roasting, baking, and sautéing preserve quercetin well. If you boil quercetin-rich vegetables, keeping the cook time short helps. Using the cooking liquid in a soup or sauce recaptures what leached out.
What Helps Your Body Absorb It
Quercetin dissolves in fat, not water, so eating it alongside dietary fat improves absorption. Adding olive oil to a salad or cooking onions in butter isn’t just tastier; it genuinely helps your body take in more quercetin. Fiber also plays a role. Research shows that prebiotics like fructooligosaccharides (a type of plant fiber found in onions, garlic, and bananas) improve quercetin bioavailability.
The food matrix matters too. One study found that quercetin baked into a cereal bar was absorbed better than the same amount taken as a capsule, probably because the manufacturing process dispersed it evenly among fats and fibers. This suggests that getting quercetin from whole foods, where it’s naturally embedded in a complex mix of fiber, fat, and other nutrients, gives your body a better shot at absorbing it than taking it in isolated form.
Food Sources Versus Supplements
Most quercetin supplements contain 500 to 1,000 mg per daily dose, far more than even a produce-heavy diet typically provides. Quercetin from food is generally recognized as safe with no established upper limit. Supplemental doses up to 1,000 mg per day for 12 weeks have shown no evidence of toxicity in clinical studies, but long-term safety data at those levels is limited.
For most people, a diet that regularly includes onions, apples (with skin), berries, leafy greens, capers, fresh herbs, and tea covers a meaningful amount of quercetin without supplements. The combination of these foods with dietary fat and fiber also creates the conditions for better absorption than a pill taken on an empty stomach.