skip to nav skip to content
You drop that delicious cookie, or that piece of pizza on the floor. Quick! Pick it up before 5 seconds and it won't have any germs on it. Right? Wrong!
A team of researchers at San Diego State University, however, has found that the germs do indeed attach themselves to edible items in less than 5 seconds. Doh! I should be dead by now. I have lived by the 5-second rule my whole life.
For the study, they used carrots which they dropped on a countertop, a kitchen sink, a table, and both a carpeted and tiled floor surface. The researchers found that the carrots were covered in germs within five seconds. The countertop was found to be dirtiest surface, with the carpeted and tiled floors in a close second and third place.
Got me to thinking. What other "rules" have I lived by that just aren't true? I found this list:
You should drink 8 glasses of water a day: The researchers who conducted the study could find no clinical evidence to support this notion. But they did dig up an article from the November 2002 American Journal of Physiology that documented the lack of evidence behind this popular recommendation. You do need to be well hydrated, but research suggests that the liquids most people drink daily - juice, milk, and decaffeinated beverages - will do the trick.
We use only 10 percent of our brains: This is a real oldie that traces its history back to Albert Einstein. Now that we know much more about neuroscience than we did 100 years ago, we can say for sure that we use much more than 10 percent of the brain, say the BMJ researchers. In fact, high-tech methods of studying the brain have not identified any inactive areas.
Reading in dim light ruins your eyes: You can get eyestrain and have trouble focusing, but there is no permanent effect on eyesight if you read in bad or low light. Consider this: rates of myopia are increasing and are higher now then they were centuries ago when people read by candlelight. What's more, the BMJ researchers found hundreds of expert opinions that conclude that reading in dim light doesn't permanently hurt your eyes.
Shaving causes your hair to grow back faster or thicker: Nope, it does not. Recent studies have confirmed that shaving has no effect on hair growth (or regrowth), write the BMJ investigators. They speculate that when shaved hair regrows, it lacks the fine taper seen at the end of unshaven hair, making it appear coarser. And the fact that it hasn't been exposed to light may make it seem darker than other hair.
Cell phones mess up hospital equipment: A Wall Street Journal article cited a medical journal report of more than 100 incidents of suspected electromagnetic interference with medical devices before 1993. But studies in England and the U.S. have found little in the way of interference and few serious effects. The BMJ reported on a survey of anesthetists that showed use of mobile phones by physicians was associated with a reduced risk of medical error or injury resulting from delays in communication. Let's see how long it takes hospitals to react to these findings and change their policies with regard to cell phone use.
Eating turkey makes you sleepy: Not so. Here, the myth is that the tryptophan in turkey causes the drowsiness. This amino acid is known to cause drowsiness, but the truth is that there's as much tryptophan in pork and cheese as there is in turkey. What's more, as the BMJ researchers noted that for tryptophan to promote sleep, you need to ingest it on an empty stomach (with no protein present) - something that's unlikely at Thanksgiving or Christmas dinner. Other factors are probably to blame for post-meal drowsiness: any big meal can make you sleepy because of a decrease in blood flow and oxygenation to the brain. And then, of course, there's the wine.