Aescin, the active ingredient in Horse Chestnut seed, tones up the walls of the veins thus improving the flow of blood back to the heart. It also relieves swelling by stopping excessive leakage through the walls of the capillaries (the tiny vessels that deliver blood to the tissues).
Kosher Horsechesnut Seed [Kof K]
Horse Chestnut's ability to relieve swelling in the legs has been confirmed in several rigorous clinical trials. In one it proved to be as effective as the uncomfortable compression stockings that are often prescribed for the problem.