Synopsis

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

Japanese knotweed (Reynoutria japonica, also known as Polygonum cuspidatum) has a history of traditional use in East Asian medicine, but its relevance as an antiviral for colds is increasingly supported by scientific investigation. The plant is notably rich in resveratrol and emodin, compounds with documented antiviral properties in vitro. Laboratory studies have shown that extracts from knotweed can inhibit the replication of several viruses, including influenza virus and some rhinoviruses, which are common causes of colds. The mechanism of action is believed to involve the inhibition of viral entry and replication, as well as modulation of the host’s immune response.

However, it is important to note that most of the scientific evidence comes from cell culture and animal studies; robust clinical trials in humans are lacking. The traditional use of knotweed in Chinese and Japanese medicine has focused more on its anti-inflammatory, antimicrobial, and circulatory benefits, with only indirect reference to its effects on respiratory infections. Thus, while the scientific rationale for its antiviral potential is promising, especially due to the presence of resveratrol, there is insufficient high-quality clinical evidence to strongly recommend knotweed for the treatment or prevention of colds at this time. Future research, particularly well-designed human trials, is needed to clarify its efficacy and safety for this use.

More about knotweed
More about Colds (antiviral)

Other ingredients used for Colds (antiviral)

Other health conditions supported by knotweed

Products containing knotweed

Metagenics PhytoGanix® Tropical Fruit
Integrative Therapeutics ProThrivers Wellness Flav Complex
Integrative Therapeutics Resveratrol Ultra HP 175mg