John Smoltz Says Candy Bar Cost Him 1990 No-Hitter, Hasn't Eaten It Since

John Smoltz says a Zagnut bar cost him a no-hitter nearly three 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 ... and claims he was going to pass out before he took the mound in the 9th if he didn't chow down on something.

So, Smoltz says he reached for a Zagnut candy bar ... and claims that doomed him.

"I go up in the clubhouse and the first thing I saw was a Zagnut, so I crush it real quick," Smoltz says. "And, one out in the ninth, I give up a 2-0 base hit to Lenny Dykstra."

So, how did Smoltz react to the candy? "I haven’t had a Zagnut since."

That's right, no delicious peanut brittle/coconut delight for Smoltz in 29 YEARS!!!