One hundred eighty-six people considered at high risk for deep vein thrombosis (DVT) who were undergoing a seven- to eight-hour plane flight were randomly assigned to receive Flite Tabs (Aidan, Tempe, AZ) or placebo at a dose of two capsules two hours before the flight and again six hours later. Each capsule contained 150 mg of a proprietary blend of Pycnogenol and nattokinase (proportions of each not specified). All participants were advised to engage in mild exercise during the flight and to drink 100 to 150 ml of water every hour. In the placebo group, DVT (determined by ultrasound scanning) developed in five subjects (5.4%), and superficial vein thrombosis developed in two subjects (total events: 7 in 92 subjects; 7.6%); all events were asymptomatic. No thrombotic events occurred in the active-treatment group (p < 0.025 for the difference in event rates between groups). Edema of the lower leg increased by a mean of 12% in the placebo group and decreased by a mean of 15% in the active-treatment group (p < 0.02 for the difference in the change between groups).
Comment: Prolonged air travel is associated with DVT, which can lead to pulmonary embolism. The increased risk of DVT during long flights may be due to in part to prolonged bending and compression of veins on the edges of the seat, leading to stasis and thrombosis. Other contributing factors may be immobility, relative hypoxia, decreased fluid intake, and dry air in airplanes. The risk of developing DVT is increased in people with a history of deep or superficial vein thrombosis, coagulation disorders, severe obesity, limited mobility, cancer within the previous two years, cardiovascular disease, or large varicose veins. Compression stockings have been shown to be effective for preventing DVT during long flights.
Nattokinase is a fibrinolytic enzyme purified from the fermented soy food Natto. When taken orally, nattokinase increases fibrinolytic activity in the blood, an effect that would be expected to reduce the risk of thrombosis. Pycnogenol is an extract of a tree bark that has been shown to inhibit platelet aggregation, increase capillary integrity, and decrease the severity of leg edema in people with venous insufficiency. The results of the present study demonstrate that supplementation with nattokinase and Pycnogenol can reduce the incidence of thrombotic events and prevent leg edema in high-risk individuals undergoing a long airline flight.
Cesarone MR, et al. Prevention of venous thrombosis in long-haul flights with Flite Tabs: the LONFLIT-FLITE randomized, controlled trial. Angiology 2003;54:531-539.
