Eating and drinking at the wheel can almost double the risk of a car crash, according to a new study.
Yet around 75 per cent of drivers drink and eat while driving, research from Privilege Insurance found.
Although drivers try to compensate for eating and drinking by driving more slowly and carefully, they are often unable to brake in enough time to avoid a collision, the study found.
The findings came following tests of motorists on a driving simulator.
The tests showed that drivers' mental workload was significantly higher when eating or drinking, suggesting that the consumption of refreshments reduces a motorist's ability to deal with other events.
So although drivers were slowing down and steering more consistently they were still not compensating enough to avoid a crash.
Participants were asked to drive an urban route once without eating, and once while eating from a bag of sweets or drinking from a bottle of water at two intervals, coinciding with a pedestrian stepping into the road.
The number of crashes doubled during the food and drink trial. Nine in ten occurred at the point the driver was eating sweets or sipping water, resulting in a collision with a pedestrian.
Dr Mark Young, a researcher lecturer from Brunel University in west London, who carried out the study on behalf of Privilege, said: "The results strongly indicate that eating or drinking while driving increases the risk of a crash.
"Drivers may not perceive the risk to be any higher than other menial in-car tasks, but the impaired reactions combined with the increased workload suggest drivers should exert caution."