A supplement derived from French maritime pine bark may help reduce the risk of developing leg clots during long air flights. Deep vein thrombosis (DVT) occurs as a result of the blood’s circulation being restricted. Long periods of inactivity or immobility, dehydration, and low humidity and low cabin pressure that occur during air flights also cause DVTs. Because leg room and seating on airplanes is cramped DVT is frequently called economy-class syndrome. Researchers show that the French maritime pine bark extract called Pycnogenol reduces leg swelling (edema) caused by lack of movement, which can increase the risk of DVTs during airplane flights lasting seven to 12 hours.