By Mark Stillman
Fliers who wear compression stockings to stop the development of deep vein thrombosis (DVT) may be wasting their time.
For years the stockings have been up there alongside passport, travel insurance and airline tickets on every flight passengers' ticklist.
But a leading aviation medicine expert has said there is no evidence to support the link between them and DVT prevention.
The condition - sometimes known as "economy class syndrome" - has caused anxiety among holidaymakers, business people and frequent fliers recently.
And Professor David Gradwell, the UK's first professor of Aerospace Medicine, said that measures such as taking aspirin and wearing the high socks are not substantiated by scientific research.
Prof Gradwell, from King's College London said the fliers at the highest risk of getting DVT are those prone to blood clots, and that where you sit on the aircraft or how much alcohol you consume is irrelevant.
But he said all passengers, especially those on long-haul flights, should try to stay hydrated and exercise in their seat or in the aisle to reduce DVT risks.
Prof Gradwell said: "The evidence to support that that is necessary is really not there. There have been things like, 'everybody should take an aspirin'... But again, it's an area of study that is probably, as yet, incomplete. To cut a long story short, the jury's still out."
He said the debate is ongoing with a lots of ifs and buts. The professor said almost anybody should be able to fly on commercial aircraft.
The exceptions are, he said, those with active tuberculosis, people who cough up blood, those with severe anaemia or those who have had a recent acute psychotic event.
Prof Gradwell said: "Flying is safe. Millions of people do it every year without any issues at all."