Blueberry Skins May Lower Cholesterol

WASHINGTON - Mar 26/07 - SNS -- USDA researchers are encouraging by tests with rodents which indicate blueberry skins may help control cholesterol levels.

Agricultural Research Service (ARS) chemist Agnes Rimando and collaborators found that feeding hamsters a diet extremely high in cholesterol, but supplemented with freeze-dried skins of rabbiteye blueberries, produced plasma total cholesterol levels 37% lower than those of hamsters fed a control diet.

Levels of LDL—or "bad"—cholesterol were 19% lower in the blueberry-supplemented hamsters.

In addition, Rimando, in the ARS Natural Products Utilization Research Unit at Oxford, Miss., found that hamsters eating the blueberry-enhanced food fared better than hamsters fed the high-cholesterol diet augmented instead with the lipid-lowering drug ciprofibrate. Animals in that group exhibited 17% less total cholesterol—and 2% less LDL cholesterol—than the control group.

The results may be linked to constituents in blueberry skins that can activate a protein involved in the breakdown and import of fats, according to Rimando. Among these constituents are resveratrol and pterostilbene, which have been cited for their antioxidant properties.

Her main collaborator in the study was chemist Wallace H. Yokoyama of the ARS Processed Foods Research Unit in Albany, Calif. The researchers used 10 hamsters per treatment group, as well as a control diet containing the high amounts of cholesterol, but no supplements.

Supplemented diets consisted of either 7.6% blueberry skins or 25 milligrams of ciprofibrate per kilogram of diet.

Rimando collaborated in another study, also described at Sunday's meeting, which demonstrated pterostilbene's potential to fight colon cancer.

In that research, led by Rutgers University scientist Bandaru S. Reddy, nine rats fed a diet supplemented with 40 parts per million of pterostilbene showed 57% fewer induced colon lesions than nine other rats fed an unsupplemented diet.