Having trouble remembering phone numbers or a professor's lecture? Try spitting out your chewing gum.

A new British study suggests that chewing flavorless gum can interfere with short-term memory.

The research, published in the Quarterly Journal of Experimental Psychology, challenges the prevailing notion that chewing gum -- at least when it's flavored -- is a performance enhancer that can boost brain power. It also provides further proof that human beings are woefully inept at completing two tasks at once.

Some argue that gum improves concentration by triggering an increase in blood flow through the brain, said lead author Michail Kozlov of Cardiff University. But his team found that an oral activity such as gum chewing can interfere with the process that's normally used to remember verbal content.

The researchers used classic short-term memory challenges, with and without gum. In one test, the volunteers were told to chew vigorously and asked to remember a sequence of randomly ordered letters. Another group repeated the experiment, but chewed naturally.

In a second test, students chewed the flavorless gum and tried to pick up the missing item in the sequence. It didn't matter whether the volunteers chewed vigorously or naturally. In both cases, "chewing has an overall adverse effect on serial recall," researchers wrote.

Flavor, however, is a still a wild card. It's what might contribute to the benefits of gum chewing, according to a 2002 study.

But because chewing gum loses its flavor in several minutes -- and unflavored gum is generally unpalatable -- "it seems advisable that chewing gum is only considered a performance enhancer as long as its flavor lasts," the researchers noted.

Or as long as you have money to buy more gum.