Since 1932 Standardized Extract Fresh Healthy Once Daily Dietary Supplement Our own laboratory analysis guarantees purity and freshness of all Thompson products. Horse chestnut seed extract was successfully revalidated as a phytomedicine in Germany in early 1994. Clinical trials support the venotonic, vascular protective, and antioxidant effects of horse chestnut seed extract standardized to escin, a saponin. The horse chestnut seed extract in this product is guaranteed to contain a minimum of 18% escin.Thompson