Polygonum Cuspidatum Root Extract
INCI: Japanese knotweed
Reviewed by Rosie · Last updated 18 Aug 2026
Also known as: Mexican bamboo, Hu Zhang
EWG Safety Score
What Is Polygonum Cuspidatum Root Extract?
Polygonum cuspidatum root extract is a plant whose root is a good source of the potent polyphenolic antioxidant trans-resveratrol, which is considered the most bioavailable form of resveratrol.
Also known as Japanese knotweed, Mexican bamboo, and, in Traditional Chinese Medicine as Hu Zhang, this plant not only helps thwart free radicals before they can damage skin, it also reduces signs of irritation.
Research has also shown this plant extract can inhibit the formation of advanced glycation end-products, or AGEs. These are collagen-damageing proteins and fats that form in skin as a reaction from exposure to sugars. Left unchecked, AGEs can contribute to wrinkles and loss of firmness.
Trans-resveratrol has been shown to fade hyperpigmentation when used in amounts of 1% or more; lower levels of Polygonum cuspidatum root in skin care remain viable for antioxidant, soothing, and other benefits.
Benefits for Your Skin
Clinical Evidence & References
- Evidence-Based Complementary and Alternative Medicine, April 2020, ePublication
- Food and Science Nutrition, June 2019, pages 2,006-2,016
- Biomedicines, September 2018, ePublication
- Evidence Based Complementary and Alternative Medicine, September 2013, ePublication
- International Journal of Preventive Medicine, April 2013, Supplement 1, pages S1-S4
- Journal of Inflammation, February 2008, ePublication
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