From the state that leads the nation in apple production, and where the annual gridiron contest between the top two universities is the "Apple Cup," comes research saying a green apple a day could keep obesity away.

Scientists at Washington State University have determined non-digestible compounds in apples -- specifically, Granny Smith apples -- may help prevent conditions associated with obesity.

The study, believed the first to assess the compounds in cultivated apple varieties grown in the Pacific Northwest, appears in the October print edition of the journal Food Chemistry.

"We know that, in general, apples are a good source of these non-digestible compounds but there are differences in varieties," food scientist Giuliana Noratto, the study's lead researcher, said in a news release. "Results from this study will help consumers to discriminate between apple varieties that can aid in the fight against obesity."

The balance of bacterial communities in the colon of obese people is disturbed, leading to the presence of microbial byproducts that can cause inflammation and influence metabolic disorders associated with obesity, Noratto said.

"What determines the balance of bacteria in our colon is the food we consume," she said, so re-establishing a healthy balance of bacteria in the colon stabilizes metabolic processes that influence inflammation and the sensation of feeling satisfied.

The researchers observed the tart green Granny Smith variety appears to benefit the growth of friendly bacteria in the colon, due to their high content of non-digestible compounds that include dietary fiber and polyphenols, as well as a low carbohydrate content.

Despite being chewed and then being subjected to stomach acid and digestive enzymes, such compounds remain intact when they reach the colon -- where they are then fermented by bacteria, which, in turn, promotes the further growth of friendly gut bacteria.

The study discovered Granny Smith apples surpass Braeburn, Fuji, Gala, Golden Delicious, McIntosh and Red Delicious in the amount of non-digestible compound content.

"The non-digestible compounds in the Granny Smith apples actually changed the proportions of fecal bacteria from obese mice to be similar to that of lean mice," Noratto said.

The find could help prevent some of the disorders associated with obesity, like the low-grade, chronic inflammation that can lead to diabetes.