From The associated Press’ Tim Booth, reporting today from spring training in Peoria, Ariz.:

Franklin Gutierrez doesn’t sound concerned yet, even if everyone with the Seattle Mariners is becoming more watchful of their center fielder and his lingering stomach problems.

For nearly a year now, the discomfort in Gutierrez’s troublesome tummy hasn’t completely gone away. it comes in waves. sometimes he can eat whatever he wants and be the Gold Glove winning center fielder for the Seattle Mariners.

Other times, he doesn’t even want to look at food.

“I’m trying not to think about it,” Gutierrez said. “I’m trying to be optimistic.”

Gutierrez returned to Seattle earlier this week to go through a bevy of tests when the discomfort returned right at the start of spring training. He spent all day Thursday getting poked and prodded to see if doctors can finally make a determination on what is causing Gutierrez his problems.

The Mariners are trying to be proactive with their young outfielder in an attempt to avoid the same second-half swoon Gutierrez went through in 2010.

The biggest question to solve: what’s causing it?

He thinks it might be food related, joking on Saturday morning that maybe it’s time to give up eating ice cream. it might be the most plausible explanation, even if a solution remains mysterious. Gutierrez hasn’t tried changing his diet, although that might be the next option.

“I’ve got no answers at all. but the good thing is I feel OK,” Gutierrez said. “because it’s early in spring training, I wanted to make sure everything was fine and not be an issue during the season.”

Last year taught Gutierrez all too well how difficult it is to manage this stomach problem in the middle of the year.

His symptoms first developed in the late spring, a general feeling throughout his stomach, not just in one specific location. Not surprisingly, early June was about the time his numbers — especially at the plate — started to take a dramatic fade.

After going 2 for 4 with a double against the Angels on June 4, Gutierrez was hitting .294. by the All-Star break, just over a month later, his average was down to .256. For the final two months of the season, Gutierrez never climbed above .253 and finished the year at .245 — the lowest of any season in his career in which he played more than 100 games.

Gutierrez didn’t want to blame his down season at the plate on his stomach problems, but admitted when he didn’t feel like eating it impacted his energy level.

“when I have those days where it doesn’t feel right, obviously you’re not eating like you are supposed to eat. You’re not getting your energy,” he said. “I’m not going to blame it on that, but I guess it was a little bit a part of that. I needed to get energy to play (my) game. you get that energy with your food.”

Remarkably, while Gutierrez was struggling at the plate, he remained one of the top defensive outfielders in baseball. He joined teammate Ichiro Suzuki in winning a Gold Glove, becoming the third Seattle center fielder — Ken Griffey Jr. and Mike Cameron the others — to win the award.

New Seattle manager Eric Wedge had Gutierrez in Cleveland at a time when Grady Sizemore was implanted in center field and Gutierrez was shuttled around the corner outfield positions just to get him in the lineup. Wedge said the coaching staff saw Gold Glove potential in Gutierrez with the Indians.

What he needs to see this spring training is consistency at the plate and more of how Gutierrez played in 2009 when he hit .283 with 18 homers and 70 RBIs.

“I need to see him a little bit more. I saw a natural progression in Cleveland,” Wedge said. “I’m anxious to see him more consistently this spring. He should be a good offensive player and a productive offensive player for us, I do believe that. to what degree, I don’t know.”

Notes: LHP Erik Bedard will start Seattle’s game on Sunday against San Diego. RHP Doug Fister is scheduled to pitch on Monday and LHP Nate Robertson is scheduled to start on Tuesday. Other pitchers scheduled to throw on Sunday include LHP Luke French and RHP Manny Delcarmen. … Sunday’s game is the first of 16 home games for the Mariners this spring.