Japanese Knotweed Extract comes from the root of Polygonum cuspidatum, a plant called Hu Zhang in traditional Chinese medicine. People use it mainly as a botanical source of resveratrol and related polyphenols. These compounds have antioxidant properties.
The extract is often taken for cardiovascular support. Some take it for occasional joint comfort or to help maintain healthy blood sugar levels. Keep in mind the evidence for those additional uses is limited.
You can find it as a capsule or tincture. Take it with a meal and follow the label for dosing. A typical daily intake provides 100 to 500 mg of resveratrol, but concentration varies by product.
Resveratrol may interact with blood thinners and could lower blood pressure. Long-term safety data are scarce. Check with a healthcare professional before taking it if you use medication or have a medical condition.