Grapes Shown to Protect Against Diabetes

New study shows that grapes may slow the progression of Type I Autoimmune

Diabetes in lab mice

May 15, 2007, 01:00 ET from California Table Grape Commission

    FRESNO, Calif., May 15 /PRNewswire/ -- A new study appearing in the
 current issue of the peer-reviewed Journal of Nutrition(1) shows that
 consuming grapes protected against the destruction of insulin-producing
 cells (known as beta cells) in the pancreas, significantly reducing the
 incidence of diabetes in lab rodents. Naturally occurring antioxidants in
 grapes known as polyphenols are believed to be responsible for this
 beneficial impact.
     The results of this study showed that grapes reduced the infiltration
 of immune cells into the islets of Langerhans, the specific area of the
 pancreas where the insulin-producing beta cells reside, thus preventing
 their damaging effects on the beta cells. Grapes also reduced the levels of
 an inflammatory protein in spleen cells, known as TNF-alpha.
     Additionally, the researchers observed that the grape diet resulted in
 a significantly higher antioxidant capacity of the blood. Higher blood
 antioxidant capacity may potentially contribute to a reduction in oxidative
 stress in the islets of Langerhans and form yet another layer of
 protection; however, this was not directly tested. The powerful antioxidant
 activity of grape polyphenols is thought to be part of the mechanism of
 protection attributed to grapes.
     "The protective effect of grapes was quite significant and very
 exciting," said principal investigator Susan J. Zunino, Ph.D. of the USDA
 Agricultural Research Service's Western Human Nutrition Research Center in
 Davis, California where the study was conducted. "In this study we observed
 firsthand their effect on two of three critical components for the
 prevention of type I diabetes: the preservation of the beta cells and the
 inhibition of inflammation. Other studies have shown that quercetin and
 anthocyanins, which are phytonutrients present in grapes, enhanced insulin
 secretion and sensitivity, which is the third critical component. Clearly
 more studies need to be done to fully define the mechanisms of action for
 the grapes and their potential as a dietary intervention for diabetes."
     Leading health experts agree that to get the benefit of phytonutrients
 found in foods, such as the polyphenols in grapes, it is best to consume
 the whole fruit as opposed to a supplement. Fresh grapes provide an array
 of natural antioxidant compounds including polyphenols, such as
 resveratrol, and other biologically active compounds in their natural
 environment, all of which may either contribute to the beneficial effects
 or provide the optimal conditions for a certain phytonutrient to exert its
 particular individual benefit.
     "This study further reinforces the growing evidence that grapes have
 anti- inflammatory and antioxidant properties that appear to offer
 significant health benefits across a number of disease states," said
 Kathleen Nave, president of the California Table Grape Commission.
     In order to ensure the scientific validity of grape health studies, a
 representative sample of fresh California grapes was collected and freeze-
 dried into an edible grape powder which contains all of the biologically
 active compounds found in fresh grapes.
     The onset of Type 1 diabetes, also known as insulin dependent diabetes
 mellitus (IDDM) is characterized by the infiltration of activated T
 lymphocytes in to an area of the pancreas known as the islets of
 Langerhans. This causes inflammation and the progressive destruction of the
 body's only insulin-producing cells, the beta cells. The destruction of
 these cells leads to a severe depletion of insulin, which is critical to
 the body's metabolism. To survive, insulin must be delivered via injection
 or pump. Type I diabetes accounts for 5-10% of all diagnosed human cases of
 diabetes, according to the American Diabetes Association.
     This study was supported by the United States Department of Agriculture
 and the National Institutes of Health. No funding was provided by the
 California Table Grape Commission. For more information go to:
     (1) Journal of Nutrition, vol.137: 1216-1221, May 2007.

SOURCE California Table Grape Commission