Evidence supporting the use of: Knotweed
For the health condition: Hepatitis

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Synopsis

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

Knotweed, specifically Polygonum cuspidatum (also known as Japanese knotweed or Hu Zhang in Traditional Chinese Medicine), has a longstanding history of use in traditional medicine systems in East Asia, including for liver-related ailments such as hepatitis. Traditional Chinese Medicine (TCM) texts describe knotweed as having properties that "clear heat," "remove toxins," and "invigorate blood," which are interpreted as beneficial in the management of hepatitis and other inflammatory liver diseases. The root is particularly valued for these purposes.

From a scientific standpoint, knotweed contains several bioactive compounds, most notably resveratrol, which has recognized antioxidant and anti-inflammatory activities. Preclinical studies (in vitro and in animal models) have shown that extracts of Japanese knotweed and its constituents may have hepatoprotective effects, such as reducing liver inflammation and oxidative stress. Limited studies suggest potential antiviral properties, but robust clinical trials in humans with hepatitis are lacking. As a result, while traditional use is well documented, scientific validation for its efficacy specifically in hepatitis is still emerging and remains insufficient for strong recommendations. Therefore, knotweed’s use for hepatitis is justified primarily by tradition, with modest supporting evidence from laboratory research, but insufficient high-quality clinical evidence.

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