The 'five-second rule' that many of us secretly adhere is an actual scientific measure of how long your food is safe to eat for, according to a group of biologists.

Final-year students at Birmingham’s Aston University found there is a "significant time factor" on the transfer of bacteria from the floor to food - basically, you have five second window to pick it up before it stops being safe to eat.

The students placed toast, pasta, biscuits and a sweet on the floor to determine that food picked-up straight after being dropped is less likely to contain common bacteria such as E. coli.

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They also determined that bacteria is least likely to transfer from carpeted surfaces, and most likely to transfer from laminate or tiled surfaces to moist foods which made contact with the floor for more than five seconds.

Meanwhile, 87 per cent of people said they would eat food they dropped on the floor regardless, a survey by the same researchers discovered. Women are the biggest believers in the five-second rule, with 81 per cent admitting to following it.

"Consuming food dropped on the floor still carries an infection risk as it very much depends on which bacteria are present on the floor at the time; however the findings of this study will bring some light relief to those who have been employing the “five-second rule” for years, despite a general consensus that it is purely a myth," Professor Anthony, who led the study, said.

"We have found evidence that transfer from indoor flooring surfaces is incredibly poor with carpet actually posing the lowest risk of bacterial transfer onto dropped food."