Snacking, moving can decrease risk of flight-related blood clots

NEW ORLEANS, Louisiana (CNN) -- Take your next airplane flight with a little food and drink, doctors advise. A snack or small meal and nonalcoholic beverage may decrease the risk of what is being called "economy class syndrome," or clot formation in the deep leg veins.

"A lot of people would not be likely to eat or drink because of anxiety," Dr. David Frid, a cardiologist at the Ohio State University Medical Center in Columbus, said last week at a conference of the American Heart Association.

Japanese researchers have found that in an airplane cabin environment, food and nonalcoholic beverages improved oxygen levels in the body by 21 percent and oxygen to the brain by 48 percent.

"After eating and drinking, blood volume may be increased," added Dr. Makoto Matsumura, assistant professor of cardiovascular surgery at the Saitama Medical School north of Tokyo, Japan.

Increased blood volume helps to keep circulation going, lessening the chance that blood can pool in the legs to form clots. Such clots become a danger when they travel to the brain or heart, causing stroke or heart attack.

Sitting too long in cramped seats -- whether on a plane or in a car -- can lead to what is being called "economy class syndrome," or clot formation in the deep veins of the legs.

An apparently healthy 28-year-old British woman died just last month from suspected economy class syndrome. She collapsed at Heathrow Airport after a 20-hour flight from the Sydney Olympics in Australia to London, England.

"Sometimes people get blood clots that go from their legs to their lungs -- pulmonary emboli," said Dr. Gerald Fletcher, a cardiologist at the Mayo Clinic in Jacksonville, Florida. "This is a risk, and it's been fairly well documented as a slight problem in the literature."

Dutch scientists recently concluded that there is no increased risk for most travelers on trips averaging 8 hours. However, they said more research is needed to determine the effects of traveling more than 15 hours, especially for people who are already at increased risk for thrombosis.

Eating too much before a flight may be less effective than eating just a bit, however, doctors said. This is because a big meal could divert blood flow to the digestive tract.

"The fact that you're sitting on an airplane for maybe 2, 3, 4, 6 hours -- that's enough to really impede some of the blood flow and maybe increase your risk for having a deep vein thrombosis," said Frid.

Fletcher and other physicians recommend that travelers get up for a walk periodically to keep circulation humming. Some even wear support stockings when flying.

If you can't move easily, at least flex your feet and ankles and shift your position in your seat now and again, doctors said.

The Air Transport Association agrees that passengers should move around periodically during flight, eat lightly and drink plenty of fluids, but limit alcohol and caffeine intake.

CNN Medical Correspondent Rhonda Rowland contributed to this report.

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American Heart Association
Air Transport Association
The Mayo Clinic
Ohio State University Medical Center
Saitama Medical School -- Japanese language site

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