Synopsis

Source of validity: Scientific
Rating (out of 5): 2

Quercetin is a plant flavonoid found in foods like onions, apples, and berries, and has a history of use in traditional medicine, but its use for treating or supporting the common cold is primarily based on emerging scientific data rather than longstanding tradition. Laboratory studies have demonstrated that quercetin possesses antiviral properties, including the ability to inhibit the replication of several respiratory viruses, such as rhinovirus and influenza. Mechanistically, quercetin is thought to modulate immune responses, reduce viral entry into cells, and exert antioxidant effects that may help mitigate the inflammatory response associated with viral infections. Several animal studies suggest that quercetin supplementation can reduce the severity or duration of viral illnesses. A handful of small, randomized controlled trials in humans have investigated quercetin for cold prevention or symptom relief, with mixed results. For example, a study published in 2010 in Pharmacological Research found that quercetin supplementation reduced the incidence of upper respiratory tract infections in physically fit individuals under heavy stress. However, other studies have not confirmed a clear benefit in the general population, and systematic reviews have concluded that while quercetin shows promise, the evidence to support its use as a cold treatment or preventative is still limited and more high-quality clinical trials are needed. Overall, quercetin’s use for colds has some scientific rationale and preliminary evidence, but it is not yet strongly supported by robust clinical data.

More about quercetin
More about Colds (antiviral)

Other ingredients used for Colds (antiviral)

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