4 Reasons to Love Quercetin in Allergy Season

Belonging to a group called flavonoids, quercetin is a naturally occurring compound found in a wide variety of fruits, vegetables, and herbs, including apples, red grapes, cocoa powder, green and black teas, broccoli, onions, and berries. It contains anti-inflammatory, anti-allergic and antioxidant properties that can help rid the body of free radicals and may even prevent some of the damage they cause!

Quercetin: a natural antihistamine

Best known for its anti-allergy and immune modulating effects, it is believed that quercetin may even provide support for those suffering from asthma and autoimmune disease! When you’re having an allergic reaction, your body shifts into protection mode and your mast cells release histamine in an effort to help expel those allergens from your body—sneezing, tearing up, or even itching. While our body’s ability to expel allergens is essential to survival, when it overreacts to those triggers, allergic reactions result and have us reaching for the closest antihistamine to block our immune response. Quercetin has been found to inhibit both the production and release of histamine and has an ability to stabilize mast cell membranes,^1,2 which may prevent many allergic inflammatory diseases including asthma, sinusitis, and rheumatoid arthritis. 

Respiratory benefits of quercetin

Animal studies have found that more than 25 percent of absorbed quercetin ends up being localized to the lungs, further adding benefit for asthmatic patients. In fact, quercetin is similar in structure to disodium cromoglycate, a drug used for asthma and bronchospasm.³ Quercetin even has an effect on the reduction of upper respiratory tract infections (URTIs). Individuals taking 1000 mg of quercetin daily for three weeks before, during, and two weeks after intensive three-day cycling training in the winter had markedly reduced incidences of URTIs. In addition, in a study with over 1000 subjects, a subgroup of individuals over 40 years old who rated themselves as physically fit reported a reduction in total sick days and URTI symptom severity with 1000 mg daily quercetin supplementation. The authors remark that the finding was interesting because “Contrary to our hypothesis, the strongest quercetin-URTI related effects were seen in a relatively low-risk group: older subjects who rated themselves as physically fit.”⁴

Quercetin and your immune system

Our T cells, which are produced by our thymus gland, are an important part of our adaptive immunity. Divided into two subsets—Th1 and Th2—their balance determines the progression of disease. While Th1-dominant responses are involved in many autoimmune diseases such as Crohn's and sarcoidosis, Th2 responses are involved in atopic disorders such as eczema, as well as allergies and parasitic infection. Quercetin has been shown to decrease Th2 cytokine production while increasing Th1 cytokine production, effectively shifting the Th1/Th2 balance in susceptible individuals.⁴ Further, healthy volunteers who took 500 mg twice a day for four weeks showed a reduction in the protein expression of BDCA-2, a molecule that figures prominently in the development of autoimmune disease.⁵ 

How quercetin improves blood pressure

Quercetin also has substantial influence on the cardiovascular system. In a systematic review and meta-analysis conducted in 2016, quercetin in doses greater than 500 mg was shown to significantly reduce both systolic and diastolic blood pressure.⁵ The benefits appear to be greater in certain populations with comorbidities such as diabetes or those who smoke, likely due to quercetin's antioxidant qualities. 

Dosing: Typical dosing is usually around 500 mg once or twice a day for the duration of symptoms. It has a fairly good safety profile, with minimal adverse effects reported. However, there still isn't much safety data available for long term use (beyond 12 weeks).⁶ 

Caution: It is not advised to supplement with quercetin if you’re pregnant or breastfeeding. Always speak to your healthcare provider before adding a new supplement to your routine to see if it’s right for you and your specific needs.

For references visit ecoparent.ca/TWF/SPR20