From the mid 1970s to the mid ‘80s, red M&M’s disappeared. American consumers had become worried about the safety of red food coloring after some questionable Russian studies prompted the FDA to look into whether one particular dye might be causing cancer in rats. But years later, the red M&M made a triumphant return, thanks in part to a college kid in Tennessee and an inside joke that took on a life of its own.Sign up for our newsletter: http://newsletter.businessinsider.com/join/brought-to-you-by