Botanical
Japanese Knotweed
Japanese knotweed (Polygonum cuspidatum) is a fast-growing perennial plant from East Asia. Its root is a main commercial source of resveratrol.
Also listed as Hu zhang, Polygonum cuspidatum, Bambou Japonais, Japanese Knotwood
Extract weight and resveratrol content differ
The trial used 200 mg of extract daily, standardized to 20% trans-resveratrol, supplying 40 mg of that compound. An unstandardized root powder is not the tested preparation. These quantities describe the experiment, not a recommended daily dose. 1
What does the European safety assessment cover?
EFSA assessed synthetic trans-resveratrol of at least 99% purity and found no safety concern at the proposed 150 mg daily intake for adults. That conclusion concerns the specified ingredient and conditions of use; it does not establish a safe dose for every knotweed extract. 2