Polyphenols from Wine and Tea May Help Regulate Blood Sugar in Type 2 Diabetics

Red wine and black tea were found to have significant alpha-glucosidase inhibitory activity while lacking alpha-amylase inhibitory activity, which suggests that they may be useful in treatments to regulate blood sugar levels in individuals with type 2 diabetes.

Investigators at the University of Massachusetts (Amherst, USA) used an in vitro enzymatic method to test red and white wines obtained from four random sources as well as four types of teas for alpha-amylase and alpha-glucosidase inhibitory potential.

They reported in the February 2008 issue of the Journal of Food Biochemistry that water extracts of black tea had the highest alpha-glucosidase inhibitory activity, followed by white tea and oolong tea. All the randomly selected red wines had significant alpha-glucosidase inhibitory activity compared to white wine. The alpha-glucosidase inhibitory activity of the tea and wines correlated to the phenolic content, antioxidant activity, and phenolic profile of the extracts. Further, these extracts had less or no alpha-amylase inhibitory activity, indicating potential to overcome the side effects of undigested starch.

"Our testing showed that red wine contains roughly ten times more polyphenolics than white wine,” said senior author Dr. Kalidas Shetty, professor of food science at the University of Massachusetts. "Laboratory results suggest that these compounds, found in many plant-based foods, may play a role in inhibiting alpha-glucosidase and slowing the passage of carbohydrates into the bloodstream. A major drawback of medications that control both enzymes is the bacterial fermentation of undigested carbohydrates, especially starch, in the colon, which can lead to side effects such as flatulence, bloating and diarrhea. Tea and wine had no effect on the breakdown of starch by alpha-amylase, which could potentially help patients avoid these side effects.”


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