John Smoltz says a Zagnut bar cost him a no-hitter nearly two decades ago ... and the Hall of Fame pitcher says he straight-up hasn't eaten the candy since!!!
The story is hilarious ... Smoltz -- who was talking about Zack Greinke's possible no-hit bid on MLB Network Wednesday night -- says back in 1990, he had some magic stuff going on as well.
He was carrying a no-hitter into the ninth inning of a Braves game against the Phillies ... but he ran into a problem -- he was STARVING.
The former ace says he hadn't eaten anything all day .