Quercetin for Hay Fever, Viruses, Cancer, and More

Uncategorized Mar 17, 2023

You've heard the expression, "An apple a day keeps the doctor away".  If this is true, one reason may be because of its quercetin content.

So what is quercetin?   It is polyphenol, flavonoid, and antioxidant all rolled into one, making this plant compound very health-beneficial and deserving of the attention it is receiving these days.


1. Anti-cancer - As a powerful antioxidant, quercetin cleans up free radicals by pairing with their single electrons and in so doing, protects from damage to DNA.  It inhibits proliferation of cancer cells by causing cell death and stopping cells from growing. 

In addition, quercetin shows particular promise in breast cancer treatment. It inhibits the expression of mutant P53 genes and can bind to estrogen receptors to inhibit the growth of breast cancer cells. 

2. Anti-inflammatory - Quercetin inhibits various enzymes that cause inflammation.  By inhibiting histamine release and decreasing pro-inflammatory cytokines it has been known to give certain anti-allergic drugs a run for their money. It is found to be effective against bronchial asthma responses, allergic rhinitis (aka hay fever) and restricted peanut-induced anaphylactic reactions.

3. Anti-viral - Quercetin's ability to inhibit the initial stages of virus infection, to interact with proteases important for viral replication, and to reduce inflammation caused by infection makes it a valuable anti-viral aid.  According to one study "quercetin has a theoretical, but significant, capability to interfere with SARS-CoV-2 replication, with the results showing this to be the fifth best compound out of 18 candidates."

4. Heart Health - Quercetin supports the cardiovascular system by lowering blood pressure and cholesterol, relaxing blood vessels, and improving circulation. 

5. Brain Health -  By improving circulation and reducing inflammation, while functioning as an anti-oxidant, quercetin supports neurological health.


While small amounts of quercetin may be founds in many fruits and vegetables, some of the richest sources are unpeeled apples, (applesauce, apple cider vinegar); onions (especially red); and capers, the condiment frequently used in Mediterranean cuisine.  It is even found in herbs such as ginger and dill weed.

Quercetin is also available as a supplement, liposomal form showing to be the most bioavailable.   Because it affects liver detoxification systems, supplemental quercetin may interact with certain medications including chemotherapy, making some more effective and some less effective.  If you are on medication, please consult a health care practitioner familiar with natural therapies and their interactions with drugs before using quercetin for therapeutic purposes.

Besides, food --  and not only apples -- but a wide variety of foods supplying a wide variety of nutrients, is still our best way to keep the doctor away!



1.  https://pubmed.ncbi.nlm.nih.gov/34709675/

2.   https://pubmed.ncbi.nlm.nih.gov/27187333/


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