If you have heard that chewing gum can help students with focus or performance - that is false.  A new study from Cardiff University in the UK says it actually does just the opposite.  The bottom line of the study was that chewing gum lessens our ability to memorize lists of letters and numbers.  The researchers did discover one exception with the chewing gum recall theory.  Subjects who chewed mint flavored gum did see temporary spike in memory.  However, as soon as the flavor wore off, their performance took a dive.