Granny Smith apples – your gut’s best friend?

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

What Noratto and colleagues found was that tart, green Granny Smith apples benefit the growth of friendly bacteria in the colon due to their high content of non-digestible compounds, including dietary fiber and polyphenols, and low content of available carbohydrates.

Despite being subjected to chewing, stomach acid and digestive enzymes, these compounds remain intact when they reach the colon. Once there, they are fermented by bacteria in the colon, which benefits the growth of friendly bacteria in the gut.

The study at Washington State University showed that Granny Smith’ss surpassed Braeburn, Fuji, Gala, Golden Delicious, McIntosh and Red Delicious in the amount of non-digestible compounds they contain.

According to the researchers 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.

The discovery could point the way towards preventing some of the disorders associated with obesity – such as low-grade, chronic inflammation – that can lead to diabetes.

Studies show that in people who are obese, the balance of bacterial communities in the colon is disturbed. This results in microbial byproducts that lead to inflammation and influence metabolic disorders associated with obesity.

“What determines the balance of bacteria in our colon is the food we consume,” Noratto said.

Re-establishing a healthy balance of bacteria in the colon stabilizes metabolic processes that influence inflammation and the sensation of feeling satisfied, or satiety, she added.

The study appears in the journal Food Chemistry.