Five-Second Food Rule: Irrelevant Common Sense

Five-second food rule

An interesting science experiment conducted by a microbiology professor and his students lent some common sense support to the five-second food rule but, in the big picture, the rule seems almost irrelevant. Why? Because eating off the floor poses less of a risk to health than everyday encounters with familiar objects, routinely perceived as innocuous.

The premise for the rule is that the longer a dropped piece of food stays on the floor, the more germs it accumulates and the less dangerous it is to one’s health. So dropped food is considered safest if picked up and eaten in a split second.

Anthony Hilton and his students at Aston University in the U.K. took a variety of foods including toast, pasta, cookies, and a sticky candy and tested for the amount of bacterial growth on each, in response to various floor surfaces and exposure times. They tested the food items on carpet and hard floors.

The researchers found that moist foods attract more bacteria than dry food and that carpets transferred less bacteria than hard floor surfaces. Of course, the longer food sat on the floor, the more bacteria it accumulated. Differences in bacteria types accounted for different rates of accumulation.

The results of the five-second food rule study are not that surprising considering the principles of surface area.  The drier the object, the more porous it becomes and the less surface area it has for direct contact with another surface (floor). And a hard flat floor offers more potential for direct contact with other objects (food).

Although the five-second food rule is consistent with modern common sense, the danger of eating food off of the floor altogether fades into irrelevancy when compared with everyday encounters with common objects. For example, the kitchen sink contains more potentially dangerous bacteria than the floor. And physical contact with handrails such as those on shopping carts, escalators, and public transportation also pose a greater threat.

Of course there is always some health risk associated with the consumption of foreign bacteria, but psychology does play an enhancing role when it comes to introducing substances into the body via the mouth. And people probably don’t realize that bringing their hands into contact with their mouths after touching foreign surfaces occurs on a daily basis, whereas the opportunity to consider the five-second food rule, to decide whether or not to eat food off of the floor, occurs very rarely.

Regardless, people do eat fallen food. When the researchers surveyed the public they found that 87 percent of  people polled would willingly eat dropped food from the floor. Women at 55 percent were more inclined to do so than men.

The five-second food rule is based on common sense regarding contact between surface areas, but falls into virtual irrelevancy within the larger view that includes surfaces with which people come into contact every day. This doesn’t mean that there is no risk in eating food off of the floor, because bacteria will always transfer; and the type of bacterial strain may make a difference in the likelihood of becoming ill.  So the practice of the five-second food rule is best avoided completely.

By Robert Wisnewski



The Los Angeles Times

The New York Times


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