An apple a day keeps the doctor away — or so we thought.

New research from the University of Southern California suggests young non-smokers with fruit- and veggie-packed diets may face a higher lung cancer risk than those with less healthy habits.

“These counter-intuitive findings raise important questions about an unknown environmental risk factor for lung cancer related to otherwise beneficial food that needs to be addressed,” Dr. Jorge Nieva, a medical oncologist and lead investigator of the study, said in a press release .

A diet rich in fruits, vegetables and whole grains is still widely seen as a cornerstone of good health.…