Scientists from Washington State University in the US discovered that non-digestible compounds found in apples can help fight disorders associated with obesity - and that Granny Smiths contain the most.
The research revealed that the sour, green Granny Smith apples promote the growth of good bacteria in the colon, due to their high content of non-digestible compounds, including dietary fibre and polyphenols, and a low amount of available carbohydrates.
This means that, despite being chewed and subjected to stomach enzymes, these compounds are still intact when they reach the colon, where they are fermented by bacteria to benefit the growth of friendly bacteria colonies.
Scientists now understand that many people with obesity have an imbalance in the bacterial communities in their colon, and this can lead to inflammation and trigger disorders such as diabetes. The non-digestible compounds in apples can help to restore this balance and prevent some of the damage of obesity.
The scientists tested the content of the compounds in Granny Smiths, Braeburn, Fuji, Gala, Golden Delicious, McIntosh and Red Delicious apple varieties and found that Granny Smiths were superior.
“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 Giuliana Noratto, a food scientist and the lead researcher, in a press release.
By re-establishing a healthy balance of gut bacteria, people can help to stabilise metabolic processes that can lead to inflammation, and prevent the disorders associated with obesity.