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Het goede van de schil van de appel*
Uit een Amerikaanse studie blijkt dat bioactieve stoffen in de schil van appels het verlies aan spiermassa tegengaan. Het verlies aan spiermassa overkomt iedereen vroeg of laat door ziekte of gewoon het ouder worden. Het gevolg van verlies van spiermassa is een langere hersteltijd bij een ziekte en hogere bloedwaarden cholesterol en glucose. De bioactieve stof is ursolzuur. Veruit het meeste ursolzuur wordt gevonden in de schil van appels verder nog in ander fruit zoals basilicum, bosbessen, cranberry’s, vlierbes, pepermunt, rozemarijn, lavendel, oregano, tijm, meidoorn en pruimen. In de studie weliswaar nog met muizen kregen deze een paar weken extra ursolzuur in de voeding. Hun spiermassa groeiden, ze verloren gewicht, bloedwaarden glucose, cholesterol en triglyceriden daalden. De onderzoekers gaan nu een studie opzetten met mensen en kijken of die resultaten ook gehaald worden en welke hoeveelheden ursolzuur nodig zijn.
Compound in apple peels found to prevent muscle wasting from aging and illness
As we get older -- or if we stop working out due to illness -- muscles can get weaker and smaller. But now comes news that a natural compound in apple peels could be the key to preventing this muscle wasting. What's more, it may also reduce body fat and lower cholesterol levels.
"Muscle atrophy causes big problems. It's also very common -- it affects most people at some point in their lives, during illness or aging. But, there's no medicine for it," says Christopher Adams, M.D., Ph.D., University of Iowa (UI) endocrinologist and senior author of the new study recently published in the journal Cell Metabolism. "We studied muscle gene activity in people with atrophy and used that information to find chemicals that might block atrophy. One of those chemicals was especially interesting. It's called ursolic acid and it's particularly concentrated in apple peels."
Dr. Adams and colleagues tested ursolic acid in mice and found that the natural compound increased both the size and strength of their muscles. "It did this by helping two hormones that build muscle: insulin-like growth factor-1 (IGF1) and insulin. Because ursolic acid increased muscle, it reduced muscle atrophy," he explained. "Surprisingly, it had some other beneficial effects in mice: for example, it reduced body fat, and lowered blood glucose and cholesterol."
Dr. Adams and his research team zeroed in on ursolic acid by using a relatively new research technique called connectivity maps. It allowed them to compare gene expression patterns in cells under different conditions. The scientists were able to figure out which genes are turned on or off in human muscle during atrophy and compared that pattern with gene expression patterns in cultured cell lines treated with a long list of different compounds.
This method revealed ursolic acid from apple peels causes a pattern of gene expression that is the opposite of the pattern caused by muscle wasting, indicating the natural compound could reverse muscle atrophy.
Next, the researchers fed mice ursolic acid in lab experiments and found the apple compound protected the animals from muscle atrophy caused by both fasting and nerve damage. Furthermore, healthy mice that ate ursolic acid developed larger, stronger muscles than mice that didn't receive the substance.
In addition, even though ursolic acid increased muscle weight in mice that ate it, it did not increase total body weight. In fact, the scientists found that mice fed ursolic acid had less body fat than mice who didn't receive the apple peel compound.
The scientists are planning human trials and already talking about finding a way to turn the natural apple peel compound into a Big Pharma drug. For now it makes sense if you want to keep your muscles strong and your body lean, to simply follow the old adage about "an apple a day keeping the doctor away". Just look for organic apples and make sure you eat the peel. (Juni 2011)