Quercetin: Potent Wound-Healing, Antiviral and Anti-Aging Agent

Scientific evidence indicates that quercetin contains strong antioxidant, anti-inflammatory and anti-ageing properties.  Although it is the most abundant flavonoid in the human diet, the concentration of quercetin in a food depends very much on how it has been cultivated.  

Today we will learn what quercetin is, its benefits to the human body and how to obtain it from food or as a supplement.

Quercetin is a plant pigment of the flavonoid group found in polyphenolic compounds in plants, and in a wide variety of vegetables and fruits.  But let's look at how quercetin acts in the human body.

Quercetin has a Dual Antioxidant Mechanism:

As a direct antioxidant by scavenging reactive oxygen species (ROS) and reactive nitrogen species (RNS) that are generated during metabolic processes or also from pollution, radiation, cleaning products that accumulate in the body and cause oxidative damage to our DNA, proteins, and lipids.

As an indirect antioxidant by activating antioxidant enzymes while inhibiting oxidative enzymes. Oxidative damage contributes to ageing as part of chronic and degenerative diseases. In this respect, quercetin may reduce the risk of acquiring age-related diseases, including heart disease.

Benefits of Quercetin in the Human Body

Quercetin Action Against Inflammation:

Quercetin exerts its anti-inflammatory activity by inhibiting inflammatory enzymes such as cyclooxygenase-2 (COX-2) and lipoxygenase by decreasing inflammatory mediators such as prostaglandins and leukotrienes (molecules involved in chronic inflammation processes, increasing vascular permeability, and thus favouring oedema in the affected area).

Quercetin's anti-inflammatory and antioxidant properties should be effective in preventing chronic diseases such as cardiovascular disease, obesity, and rheumatoid arthritis.

Antioxidant Action Against High Blood Pressure

Untreated hypertension can lead to heart disease and stroke.  Preclinical results suggest that quercetin contributes its antioxidant action to promote cardiovascular health (study).

Quercetin Effective in Wound Healing:

Wounds need to heal quickly to prevent infection. However, if they heal too quickly, excessively fibrous tissue forms.  This process, known as fibrosis, leads to scarring, which causes both functional and aesthetic problems.  Quercetin has anti-fibrotic properties and some studies have shown quercetin's potential to improve wound healing and reduce scar formation. (study)

Onion extract containing quercetin, as well as other phenolic compounds, is an ingredient present in many commercial wound healing gels.  A meta-analysis of 13 studies involving 600 people who used healing gels found that methodologies differed markedly with follow-up periods ranging from 10 weeks to 6 months.

There were different results probably due to the use of different formulations or the amount of quercetin contained in the products.  More tests with standardised methods are needed to confirm whether quercetin actually has healthy healing effects in humans. (study)

Quercetin Against Viral Infections:

One mechanism by which quercetin exerts beneficial effects rests in its ability to serve as an ionophore.  An ionophore is a compound that can transport ions across the semi-permeable lipid bilayer surrounding cells.

Of particular relevance in viral disease is the activity of zinc, an essential nutrient that inhibits the action of RNA-dependent RNA polymerase (RdRp), the critical enzyme for the replication of SARS-CoV-2 type RNA viruses.

Essentially, what zinc does is block the ability of viruses to replicate.  However, zinc is a positively charged ion that cannot enter cells to perform its function without the help of a transporter.  Quercetin is a well-known ionophore.

Quercetin as an Anti-Ageing Agent

Senescence is a condition or process of cell deterioration that occurs with age.  Senescent cells accumulate in the body over time and have properties that distinguish them from normal cells.  For example, they do not replicate and instead of dying, they secrete dangerous molecules that damage or kill neighbouring cells. (Study)

Research indicates that certain substances known as senolytic compounds may help treat age-related diseases.  One example is that directly targeting senescent cells could benefit chronic conditions that reduce health and lifespan such as obesity and diabetes, as senescent cells accumulate in the fat and other tissues of people with these conditions. (study)

Obesity causes an early programme of senescence in the fat cells of obese people.  Elimination of these cells could alleviate the complications of these conditions and increase insulin sensitivity.  In addition, the decrease in senescent cells should reduce age-related frailty.

Quercetin is one of the first senolytic compounds discovered to be beneficial against the effects of ageing.  Although quercetin alone cannot eliminate senescent cell types, it does act together with another agent and is usually applied with Dasatinib, an anti-cancer drug and whose combination is known as DQ.

Together with the drug Dasatinib, quercetin could also act to combat osteoporosis, pulmonary fibrosis and even kidney disease as a consequence of diabetes, hypertension and obesity itself.

Where Quercetin can be Found

Quercetin found in food is in the form of glycosides, bound to a sugar molecule, while the supplemental form of quercetin is usually in the form of an aglycone.  Quercetin aglycone can passively diffuse through the wall of the small intestine or be transported by the sodium/glucose cotransporter 1.  Once absorbed, quercetin undergoes extensive biotransformation in the liver and as a consequence, the product delivered to cells is often markedly different from the original. (study)

Back to food sources containing quercetin, some known quercetin-containing foods are listed in the table below:

The bioavailability, or how much quercetin enters the bloodstream, is not very much, as its absorption is influenced by several factors such as dosage, planting protocol, harvesting and formulation, but also the metabolic individuality of the person consuming it, as the state of the intestinal flora depends on how well or poorly quercetin is absorbed.

The benefits of quercetin are highly promising, but the best strategy for now is to consume organic foods with a high quercetin content and maintain a healthy colon to obtain all the benefits it provides.