Scientists from the Washington State University discovered that the Granny Smith apple variety is abundant in non-digestible compounds.
"The non-digestible compounds in the Granny Smith apples actually changed the proportions of faecal bacteria from obese mice to be similar to that of lean mice," said food scientist Giuliana Noratto, the study's lead researcher.
The 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 fibre and polyphenols and low content of 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.
"Re-establishing a healthy balance of bacteria in the colon stabilises metabolic processes that influence inflammation and the sensation of feeling satisfied, or satiety," Noratto added.
The discovery could help prevent some of the disorders associated with obesity such as low-grade, chronic inflammation that can lead to diabetes.
The study appeared in the journal Food Chemistry.