Quercetin is a flavonoid found in plants and food items such as green tea, onions, apples, berries, and Ginkgo biloba.

Quercetin’s health benefits come from flavonoids. Flavonoids are phytonutrients or plant chemicals that exhibit various biological activities including “antiallergenic, antiviral, anti-inflammatory, and vasodilating actions.” Quercetin has antioxidant and anti-inflammatory properties.

It has been used to aid in the treatment of cardiovascular conditions, chronic inflammation, arthritis, bladder infections, and diabetes. As an antioxidant, it protects the body against free radicals—unstable molecules that can damage living cells and healthy tissues.

Free radicals can be triggered by pollution, radiation, greenhouse gases, cigarette smoke, and chemotherapy. Quercetin can also help prevent neurodegenerative diseases like Parkinson’s or Alzheimer’s through its antioxidant properties. By fighting off free radicals, it can protect the body against oxidative stress. Oxidative stress is a factor in the development of these diseases.

Studies also suggest that flavonoids like quercetin have the potential to protect neurons from injury caused by neurotoxins. They also enhance cognitive functions as well as memory and learning. Quercetin can help manage chronic inflammation and relieve allergy symptoms.

It inhibits the release of histamine from mast cells and acts as a “natural antihistamine.” Mast cells are known to be an “immune gateway” to the brain, the environment, and emotional stress.

In 2016, a study by the American Heart and Stroke Association found that quercetin supplements “could be an effective way to reduce blood pressure.”

Other benefits include gastroprotective action attributed to its “free radical scavenging properties or its increased gastric mucus production.” It has been noted for its antibacterial properties against bacteria affecting particular systems including gastrointestinal, dermal, urinary and respiratory. Its antiviral characteristics have also been found to be effective against viruses like adenovirus, herpes simplex, Japanese encephalitis and respiratory syncytial.

Quercetin And Cancer

Medical and health professionals have also noted the promising anti-cancer properties of quercetin. One of these properties helps prevent the spread of cancer cells and tumor growth. One report(nature.com/articles/srep24049) highlighted this naturally occurring flavonoid’s potential in cancer treatment. Researchers noted that quercetin “induces cytotoxicity in cancer cells.”

Cytotoxicity refers to the ability to be toxic to cells. Chemotherapy is an example of cytotoxic therapy. The cytotoxic effect of quercetin was tested with ellagic acid—a micronutrient found in fruits and vegetables and that is also known for antioxidant properties.

Another key highlight of the study is that quercetin treatment “leads to apoptosis” or programmed cell death. It was also found to “activate the intrinsic pathway of apoptosis” by directly interacting with the DNA.