Dr. Hibberd's answer:
 

Extended plane flight or car travel is a risk factor for peripheral clot formation, especially for those over the age of 50. It is the prolonged immobility that poses your risks for blood clot development in your legs. Pre-trip diet and exercise seem to have little effect one way or the other, but weight management is important to keep your risks lower.
 

One baby aspirin (81 milligrams) taken daily for several days before your trip, and continuing until your return, will offer some protection. Be sure to stretch your legs hourly and get up and take a few steps around the cabin during your trip to reduce venous pooling and stasis. Sometimes support hose may be recommended, but if you do use these, be sure they are waist high and not cut off at the calf, knee, or thigh. The shorter lengths of support hose may actually increase your chances of clot development in areas above the stocking, especially when on long trips.
 

Stay well hydrated with water during your trip, and eat sensibly. A glass or two of wine would be fine, but I do not see this as a clot preventer for travel purposes. Always check with your personal physician for vaccine recommendations and medication guidance before your trip, as well as for ideas to reduce your personal risk of travel-associated blood clots. Enjoy your trip!