The five-second rule is legit, according to science

4 Feb 2016

It turns out you’re right to live by the five-second rule, eating everything and anything moments after it lands on the floor. If anything, you have even longer.

A new video for a Discovery Science show called The Quick and the Curious – hosted by former NASA engineer Mark Rober – goes into detail, with passersby encouraged to eat a cookie that’s just landed on the ground.

The segment, which is presented by NASA’s Mike Meacham, is as basic as it is fun. It turns out that, far from five seconds being the cut-off point (often followed by blessing your crumbling biscuit), you’re actually golden for half a minute.

Well, half a minute depending on the environment. And, surprisingly, dropping food on a rug actually gives you more time to pick it back up than if you drop it on the lino in your kitchen. This is because rugs have less surface area touching the food.

This gives you time, you see.

“When any food flops on the floor, certain small amounts of bacteria will jump aboard immediately,” explains Rober, who narrates the segment. However, it takes a while before your favourite snack is compromised.

That is because bacteria moves incredibly slowly. But, obviously, time is against you. For example, food with moisture when left for more than 30 seconds on the floor picks up more than 10 times the bacteria than when it is picked up in three seconds or less.

“E-coli, salmonella and listeria love wet environments. They absorb water for the nutrients they need to grow and multiply.”

So 30 seconds is grand, within reason. But it’s probably best to stick to the five-second rule. Other researchers agree.

Dropping food image, via Shutterstock

Gordon Hunt was a journalist with Silicon Republic