The woman who stuck pins, needles and nails in food at a Calgary Co-op has lost her appeal.

Tatyana Granada was convicted of four counts each of trespassing and mischief last year.

In early 2010, the sharp objects were found in food for sale on four occasions at the Oakridge Co-op.

The Calgary mother was originally arrested for shoplifting from the same store a few months earlier.

Granada appealed the mischief charges, arguing the trial judge had erred when considering expert testimony.

A three-member appeal panel of judges dismissed that argument.

Granada will remain in custody until she finishes serving her three-year sentence.