Known as a flavonoid, quercetin stands out for its robust antioxidant properties. Antioxidants play a critical role in protecting our cells from oxidative stress, which occurs when harmful molecules called free radicals accumulate in the body. Over time, this oxidative stress can contribute to ageing and health concerns, including chronic conditions. [1] [2] 

Quercetin As a Natural Antioxidant 

Among flavonoids, quercetin stands out as one of the most powerful in protecting the body from reactive oxygen species, which can harm cells. Similar to other compounds like myricetin, quercetin has features that make it excellent at preventing the oxidation of fats in the body. It works by stopping the initial steps of oxidation and breaking the chain reactions that lead to further damage.  [2] [4] 

Quercetin’s antioxidant power also helps reduce the impact of free radicals during allergic responses, protecting cells from injury. Additionally, it supports the body’s repair systems, including enzymes that restore damaged DNA, proteins, and cell membranes, ensuring tissues can recover and maintain their health. [3] 

Quercetin: An Inflammation Fighter   

Inflammation is the body’s natural defense mechanism, triggered when the immune system detects injury or infection. In the short term, inflammation is helpful- it aids healing and protects against harm. However, when inflammation persists without a clear cause, it can lead to ongoing discomfort and health challenges. [5] 

What sets quercetin apart is its dual role as both an antioxidant and an anti-inflammatory agent. While it neutralises free radicals to prevent cellular damage, quercetin also tackles inflammation at its root, helping to calm the body’s immune responses. Quercetin’s anti-inflammatory properties work by reducing the production of inflammatory cytokines and enzymes, making it a valuable natural option for managing various inflammatory conditions.

Additionally, it offers cardiovascular benefits, such as improving the health of blood vessel linings (endothelial function). These qualities make quercetin a promising compound for supporting heart health and addressing cardiovascular concerns. [6] 

What are the Benefits of Quercetin? 

Supports Immune Function 

Quercetin has a remarkable ability to fine-tune the immune system. It can either activate or suppress immune responses based on the body’s needs, a balancing act known as immunomodulation. For example, if the immune system is overactive- such as during allergies or chronic inflammation- quercetin helps calm it down. On the other hand, if the immune system needs a boost to fight off illness, quercetin supports its activity. This unique property ensures that the immune system functions optimally. [8]  

Quercetin boosts the immune system in many ways. It encourages the production of immune-supporting proteins like interferon-γ (IFN-γ) while reducing others, like IL-4, that may contribute to inflammation. This advanced effect helps maintain a healthy balance in immune function, which is essential for fighting off infections while avoiding unnecessary inflammation. [9] 

A study testing 1,000 mg of quercetin daily for two weeks in young, untrained men found that it reduced inflammation and oxidative stress after exercise and improved the activity of certain immune cells. Quercetin also helped lower the rates of illness in athletes under physical stress while strengthening their natural immune defenses. [8] 

May Support Gut Health   

The digestive system plays a key role in immune health, as it houses a significant portion of the body’s immune cells. Quercetin helps stabilise mast cells, which are immune cells involved in allergic responses and gut inflammation. When mast cells become overactive, they release substances like histamine that can lead to discomfort and digestive issues. By calming these cells, quercetin can protect the gut lining and promote a healthy digestive environment, reducing the risk of irritation or imbalance. [8] 

May Block Inflammatory Signals   

At a molecular level, quercetin may target and disrupt pathways that drive inflammation. It blocks the activity of key enzymes like COX and LOX according to an invitro study on various cell lines, COX and LOX are responsible for producing inflammation-promoting substances in the body, which can cause pain, discomfort, and even harm if it occurs in healthy tissues or lasts too long.   [8] [5] 

Can Quercetin Help Relieve Allergy Symptoms? 

Polyphenols, natural compounds found in plants, are powerful agents in managing allergies due to their ability to influence immune responses. Quercetin, a type of polyphenol, is particularly effective at stabilising mast cells, which play a key role in releasing histamine and other substances that trigger allergic symptoms. By preventing the release of these mediators, quercetin can help alleviate common allergy symptoms. It also balances immune cell activity, improving the ratio of Th1 and Th2 cells- immune cell types involved in allergic responses- and reducing the production of IgE antibodies, which are also associated with allergy symptoms.  [9] 

Quercetin’s anti-inflammatory effects further enhance its role in managing allergic and inflammatory conditions. It blocks the activity of enzymes and proteins that drive inflammation, including histamine, cytokines like IL-4, and inflammatory molecules like leukotrienes. Additionally, quercetin regulates immune signaling pathways, stabilising cell membranes and preventing the overactivation of mast cells and basophils, which are key players in allergic reactions. [9] 

As ongoing research uncovers more about quercetin’s benefits, it remains a promising natural option for reducing inflammation, protecting against oxidative stress, and supporting allergy symptoms. Adding quercetin-rich foods like apples, onions, and berries to your diet- or considering taking it in supplement form- could be a simple way to enhance your health.  

Remember to always consult your healthcare practitioner when starting a new supplement regimen.