Apples May Help Fight Obesity
A recent study carried out by the University of Iowa, USA revealed that Ursolic acid, a compound found in apple peels may have the ability to fight off obesity but before going any further, we shall first get to learn a bit about what Ursolic acid is all about to better understand how it aides in burning calories.
What is ursolic acid?
Ursolic acid is a pentacyclic triterpene acid that is used in cosmetics and that is also capable of inhibiting various types of cancer cells by inhibiting theSTAT3 activation pathway and human fibrosarcoma cells by reducing the expression of matrix metalloproteinase-9 by acting through the glucocorticoid receptor. It may also decrease proliferation of cancer cells and induce apoptosis.
Ursolic acid is present in many plants, including apples, basil, bilberries, cranberries, elder flower, peppermint, rosemary, lavender, oregano, thyme, hawthorn, and prunes. Apple peels contain large quantities of Ursolic acid and related compounds.
Ursolic acid can serve as a starting material for synthesis of more potent bioactive derivatives, such as antitumor agents. It has been found to reduce muscle atrophy and to stimulate muscle growth in mice. Ursolic acid has potential use as a cardioprotective compound.
Ursolic acid has been shown to increase the amount of muscle and brown fat and decrease obesity and associated conditions when added to diets fed to mice. Other names for Ursolic acid include 3-beta-3-hydroxy-urs-12-ene-28-oic-acid, 3-β-hydroxy-urs-12-en-28-oic acid, urson, prunol, and malol.
(Source: http://en.wikipedia.org/wiki/Ursolic_acid)
In the Iowa study, mice that consumed a high fat diet over a couple of weeks inclusive of Ursolic acid developed more muscle mass and more calorie-burning brown fat than mice that ate the same diet without the Ursolic acid.
“Since muscle is very good at burning calories, the increased muscle in Ursolic acid-treated mice may be sufficient to explain how ursolic acid reduces obesity,” said study researcher Dr. Christopher Adams, an associate professor of internal medicine at the University of Iowa. However, the increase in brown fat, an unexpected finding, may also help protect against obesity, Adams went on to say, noting that researchers don’t know how the compound might exert this effect on brown fat.
Previous studies had revealed that Ursolic acid increased muscle mass and strength in healthy mice though in their new study, they tested the compound in mice likely to develop obesity and metabolic syndrome. In humans, having metabolic syndrome means having at least three major risk factors for heart disease such as too much abdominal fat, high triglycerides and high blood pressure.
The researchers found that the mice that consumed Ursolic acid gained less weight and were less likely to develop conditions similar to pre-diabetes and fatty liver disease despite the fact that they ate more food than the mice that did not consume the compound. There was however no difference in physical activity between the groups, the researchers said. 
The researchers have not tested the compound in humans and research in rodents often doesn’t produce the same results in humans; “We don’t know if Ursolic acid will benefit people,” Adams said.
Still, Adams noted that it’s possible the compound could someday be used as treatment for muscle wasting, a condition which occurs in healthy people during aging and also in some conditions such as cancer.
Some studies have linked increased levels of brown fat with lower levels of obesity and healthier levels of blood sugar and fats, according to the researchers. The researchers went ahead and measured the mice’s energy expenditure and found that those which fed on Ursolic acid burned more calories than mice that didn’t consume the chemical.
Some evidence suggests that brown fat may be helpful in preventing obesity and diabetes, something that Adams backed up by stating, “Brown fat is beneficial and people are trying to figure out ways to increase it”. “Our next step is to determine if Ursolic acid can help patients.”
The study was published June 20 in the journal PLoS ONE, and was funded by the Fraternal Order of Eagles Diabetes Research Center at the University of Iowa, the National Institutes of Health, the Department of Veterans Affairs and the University of Iowa Research Foundation.