http://news.bbc.co.uk/2/hi/uk_news/6535517.stmDiet clears drinking-arrest pilot
Virgin 747
The flight was delayed as a substitute pilot was found
A pilot arrested on suspicion of being over the alcohol limit has been cleared after tests found heavy dieting had caused his breath to smell like drink.
The Virgin Atlantic employee - held at Heathrow on 31 March before a flight to New York - had failed a breathalyser.
But samples taken from the 47-year-old prove his blood-alcohol level was consistent with a non-drinker.
Scientists say low-carbohydrate diets can produce acetone in the body, which may fool breath test equipment.
The long-serving pilot was said to have been on a heavy diet for a long period.
Acetone is a substance produced by the body as it tries to make up the glucose absent from low-carbohydrate diets.
Wayne Jones, a professor in experimental alcohol research at the University of Linkoping in Sweden, told the BBC breathalysers can sometimes fail to distinguish acetone from drink.
"Then there's a risk you get a false positive reading," he said.
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