A new study in mice finds that ursolic acid, a compound naturally present in apple peel, partially protected the animals against obesity and some of its harmful effects such as pre-diabetes and fatty liver disease.
Lead researcher Christopher Adams, of the University of Iowa (UI) in the United States, and colleagues, said although they found ursolic acid increased skeletal muscle and brown fat in the mice, which in turn led to increased calorie burning, they didn’t investigate the underlying biology, and so can’t say if the same would happen in humans.
The team writes about the findings in a paper published online in PLoS ONE on 20 June.
In their background information, they describe how they recently found “ursolic acid increases skeletal muscle Akt activity and stimulates muscle growth in non-obese mice”.
Akt is a protein that plays an important role in a number of cell processes, including burning glucose to make energy.
Muscle is an efficient burner of calories, so this might explain the reduced obesity in the mice treated with ursolic acid, suggest the researchers.
In a statement to the press, Adams, who is associate professor of internal medicine and a Faculty Scholar at the Fraternal Order of Eagles Diabetes Research Center at the UI, said this kind of research is important because it helps to develop ways to treat muscle wasting.
“In this study, we tested ursolic acid in mice on a high-fat diet – a mouse model of obesity and metabolic syndrome. Once again, ursolic acid increased skeletal muscle,” said Adams, adding that “Interestingly, it also reduced obesity, pre-diabetes, and fatty liver disease.”
Adams said they were surprised to find the compound also increased brown fat, another type of tissue that is very good at burning calories. This suggests another reason why ursolic acid may have helped protect the mice from obesity.
For the study, the team fed two groups of mice on the same high-fat diet for several weeks, except that one group was also fed ursolic acid supplement.