Improves Leg Veins and Circulation What It Is Used For: For centuries, horse chestnut seeds, leaves, bark, and flowers have been used for a variety of conditions and diseases. Horse chestnut seed extract has been used to treat chronic venous insufficiency (a condition in which the veins do not efficiently return blood from the legs to the heart). This condition is associated with varicose veins, pain, ankle swelling, feelings of heaviness, itching, and nighttime leg cramping. The seed extract has also been used for hemorrhoids.