10 Foods High in Quercetin (+ 5 Benefits)

We have all heard the health pitch, "an apple a day keeps the doctor away," but do we know why? In addition to being a great source of fiber and vitamins, apples are a great source of health-promoting polyphenols like quercetin.

If you haven't heard of quercetin, you're certainly not alone; zinc and vitamins C and D tend to get all the credit when it comes to immune health support. Strange name notwithstanding, however, quercetin might be the most underrated nutrient in your diet. And its benefits go well beyond shoring up your body's natural defenses.

So what is quercetin—and aside from apples, what other foods can you find it in?

What is quercetin?

Quercetin belongs to a group of plant compounds known as dietary flavonoids, which are a type of polyphenol that makes up the basis for pigments of many different plants. That's why you always hear advice to "eat the rainbow"—those brightly colored fruits and vegetables get their bold hues from health-promoting flavonoids. Quercetin is a true stand-out among other flavonoids, though, because it has many unique—and beneficial—biological properties.

Like vitamin C, quercetin is an antioxidant, which means it helps fight off free radicals which can cause oxidative stress...and if there's one thing we all need less of to maintain our health, it's free radicals!

5 quercetin benefits

How, specifically, does quercetin benefit your health? Here are five important ways this flavonoid supports you from head to toe:

1. Healthy cells

   – Senescent cells are the old cells that accumulate with aging. Quercetin is increasingly achieving recognition as a senolytic, meaning it helps remove these undesired cells—leaving the healthy, youthful, properly functioning cells to do their jobs.

2. Immune system health

   – Quercetin is an antioxidant which certainly belongs on our list of immune supporting supplements. In a large randomized-controlled trial, 12 weeks of quercetin intake (1000 mg daily) compared to placebo, produced beneficial effects including a smaller number of days of experiencing immune challenges related to the upper respiratory tract.

3. Promotes a healthy inflammatory response

   – Inflammation is a normal part of the human experience; what matters is whether your body responds in a healthy way…and quercetin appears to promote exactly that. In a meta-analysis of clinical trials, quercetin supplementation in a subgroup was associated with maintaining already-healthy levels of cytokines such as C-reactive protein.

4. Already-healthy blood sugar support

   – A separate study found that this same dosage of quercetin also supported already-healthy blood sugar levels.

5. Supports already-healthy blood pressure

   – A meta-analysis of clinical trials found that supplementing with 500 mg or more of quercetin helped maintain blood pressure in healthy ranges.

10 Foods High in Quercetin

So now that you know how many health benefits quercetin can deliver, the question is—how can you get more of this dietary flavonoid on your plate? Check out our food list below and discover some delicious ways to increase your intake of the most underrated nutrient we can think of! (Note that as is always the case with produce, the amount of nutrients per serving will vary according to the crop.)

Fruits high in quercetin

1. Dark-colored grapes

   – 3 mg per 100 grams (a typical bunch). These fruits are great sources of many polyphenols, most famously resveratrol, which may target anti-aging pathways. Red wine contains roughly 3 mg of quercetin per 100 ml, which is just under half a cup. Shiraz, however, may contain higher amounts. White wine, which comes from green grapes, has on average fewer polyphenols (including quercetin) than red wine.

2. Apples

   – 5 mg per 100 grams (roughly half an apple). Apples are probably the most common food that's a good source of quercetin. (And, if there's any food on our list that's likely already in most people's diets, it's an apple!)

3. Berries

   – Depending on variety, flavonoid-rich cranberries could have as many as 22 mg per 100 g and blueberries have 7-14 mg per 100 g (which equals about a cup). Berries are also great sources of antioxidants (look out, free radicals!) as well as polyphenols called anthocyanins, which provide wide-ranging health benefits.

Vegetables high in quercetin

4. Kale

   – 8 mg per 100 grams (about a cup). Like broccoli, kale is a great leafy green that supports cell health. In addition, kale is a great source of the carotenoid's lutein and zeaxanthin, which are concentrated in the retina and support healthy vision.

5. Red onions

   – 39 mg per 100 g (roughly a small onion). All onions contain quercetin; but due to their pigment, red onions have the highest flavonoid content, including quercetin. The way of cooking can reduce quercetin content. So, hold back on boiling and frying to get the maximum flavonoid intake from these pungent vegetables.

6. Broccoli (raw)

   – 3 mg per 100 grams (a small bowl). Broccoli and other cruciferous vegetables are a rich source of vitamins and minerals in addition to healthy cell promoting compounds, such as sulforaphane and indole-3-carbinol. And, they're also a good source of additional antioxidants…all the more reason to add them to your diet.

Other food sources of quercetin

7. Buckwheat

   – Up to 36 mg per 100 grams (about a cup full). Not only is buckwheat a good way to increase your quercetin intake, but it's a great substitute for wheat if you are eating gluten free. (It may have the word "wheat" in it, but don't be fooled!) Buckwheat works great as a base in bowls of mixed foods. Try a stir-fry of other plant foods if you're craving something savory or throw in sweeter quercetin-rich foods like berries or other fresh fruit, for a breakfast porridge worth waking up for.

8. Green tea

   – 2.63 mg per 100 ml (just under half a cup). Green tea also provides high amounts of a polyphenol called EGCG which helps maintain cholesterol and glucose levels already within the normal range, supports brain and nerve health, and provides a broad array of cellular health support. If you're still not sold, green tea also has wonderful antioxidant properties...so drink up!

9. Dill

   – 55 mg per 100 grams (this may take 2-3 typical servings). This herb is in the same family as parsley and celery but has a feathery texture. Use it as a garnish not just for taste, but also to create a pleasant aroma.

10. Capers

    – 365 mg per 100 grams (this may take 2-3 typical servings). Capers are the richest food source of quercetin per gram! Capers are flower buds of the caper bush before they bloom. They are usually used as a seasoning, most commonly on salads and salmon. While not currently a popular food in the U.S., capers are considered a superfood and are garnering more interest.

Does quercetin have side effects?

Like many supplements, quercetin is not known to have side effects. The FDA considers quercetin as generally recognized as safe at levels up to 500 mg serving; however, dosages much higher than this have also demonstrated safety.

How to choose a high-quality quercetin supplement?

Quercetin on its own is not very bioavailable, meaning it is not easy to absorb. Research shows that combining quercetin with fibers from fenugreek seeds increases bioavailability: enhancing "free" quercetin up to 18x and delivering up to 62x better total bioavailability than your "standard" quercetin formulas. This results in a science-based quercetin supplement that far outclasses standard quercetin formulations.

Can I get enough quercetin from my diet?

On average, the American diet only provides around 6-18 mg of quercetin daily. Eating more foods rich in quercetin can help you beat the average intake and provide additional health benefits due to its antioxidant content, but to receive the most benefits, a good quercetin supplement will provide a clinically studied dose and delivery.

How much quercetin can I take?

In a clinical trial, quercetin intake of 2000 mg daily was safely used for a one-week duration. Always follow the dosage and directions on the bottle.

What other dietary supplements pair well with quercetin?

• Quercetin with zinc

  
  Zinc is well-known for its immune supporting properties, which may complement the immune benefits of quercetin. One study found that quercetin acts as a zinc ionophore, transporting zinc cations through the plasma membrane. This study suggests that quercetin may help increase zinc absorption.

• Quercetin with other senolytics

  
  There are certain immune supplements that work best together. Research suggests that taking quercetin with other senolytics such as fisetin, theaflavins and apigenin may result in a synergistic benefit on the removal of senescent cells.

• Quercetin with vitamin C

  
  Quercetin and vitamin C are often present together in many foods, especially citrus fruits, and a research review suggests that vitamin C and quercetin co-administration may exert a synergistic immune defense. Life Extension offers a supplement containing both vitamin C and quercetin to take advantage of these dual benefits.

References

• Chakrawarti, L et al. "Therapeutic effects of EGCG: a patent review." Expert opinion on therapeutic patents. August 2016. https://pubmed.ncbi.nlm.nih.gov/27338088/
• Coyle, D. "Sulforaphane: Benefits, Side Effects, and Food Sources." Healthline. February 2019. https://www.healthline.com/nutrition/sulforaphane
• Heinz, S et al. "Quercetin supplementation and upper respiratory tract infection: A randomized community clinical trial." Pharmacological research. May 2010. https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC7128946/
• Husam Dabbagh-Bazarbachi et al. "Zinc Ionophore Activity of Quercetin and Epigallocatechin-gallate: From Hepa 1-6 Cells to a Liposome Model." Journal of Agricultural and Food Chemistry. July 2014. https://pubs.acs.org/doi/abs/10.1021/jf5014633
  
• Kirkland, JL, and T Tchkonia. "Senolytic drugs: from discovery to translation." Journal of internal medicine. August 2020, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7405395/
• Kokotou, MG et al. "High resolution mass spectrometry studies of sulforaphane and indole-3-carbinol in broccoli." Food chemistry. December 2017.  https://pubmed.ncbi.nlm.nih.gov/28764036/
• Ostadmohammadi, V et al. "Effects of quercetin supplementation on glycemic control among patients with metabolic syndrome and related disorders: A systematic review and meta-analysis of randomized controlled trials." Phytotherapy research. May 2019, https://pubmed.ncbi.nlm.nih.gov/30848564/
• Serban, MC et al. "Effects of Quercetin on Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials." Journal of the American Heart Association. July 2016. https://pubmed.ncbi.nlm.nih.gov/27405810/
• Walsh, RP et al. "Variation in Carotenoid Content of Kale and Other Vegetables: A Review of Pre- and Post-harvest Effects." Journal of agricultural and food chemistry. November 2015. https://pubmed.ncbi.nlm.nih.gov/26477753/
• "Phenol-Explorer." http://phenol-explorer.eu/
• "Vitamin C – Summary," Linus Pauling Institute. https://lpi.oregonstate.edu/mic/vitamins/vitamin-C