April 2008 - Red wine has been shown to protect people from heart disease, even when they follow a diet high in saturated fat, and the healing powers of tea are becoming the stuff of legend. Now, researchers at the University of Massachusetts Amherst have shown that these beverages may hold promise for regulating the blood sugar of people with type 2 diabetes.
Results have been published in the Journal of Food Biochemistry. Researchers include food scientists Kalidas Shetty, Young-In Kwon and Emmanouil Apostolidis.
"Levels of blood sugar, or blood glucose, rise sharply in patients with type 2 diabetes immediately following a meal," says Shetty. "Red wine and tea contain natural antioxidants that may slow the passage of glucose through the small intestine and eventually into the bloodstream and prevent this spike, which is an important step in managing this disease."
One of the main challenges in managing diabetes is keeping blood sugar levels as normal as possible with few major fluctuations, which can prevent the disease from contributing to heart disease and high blood pressure as well as damaging the eyes, kidneys, nerves and blood vessels.
Both red and white wines were tested in the laboratory using in vitro enzyme studies to determine how well they could inhibit the activity of a target enzyme called alpha-glucosidase, responsible for triggering the absorption of glucose by the small intestine. Red wine was the winner, able to inhibit the enzyme by nearly 100 percent. Values for white wine hovered around 20 percent.
This was clearly related to the amount of a specific type of antioxidants, called polyphenolics, found in the wines. "Our testing showed that red wine contains roughly ten times more polyphenolics than white wine," says Shetty. "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."
Alpha-glucosidase is the target for current drugs used to treat type 2 diabetes and the development of new drugs.
The team also tested four kinds of tea, including black, oolong, white and green teas. Water extracts of black tea had the highest effect on inhibiting the activity of alpha-glucosidase, followed by white tea and oolong tea.
Wine and tea had no effect on a pancreatic enzyme called alpha-amylase that breaks down starch, which could help patients avoid the side effects of medications used to control blood sugar.
"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," says Shetty. "Tea and wine had no effect on the breakdown of starch by alpha-amylase, which could potentially help patients avoid these side effects."
Another benefit is that the polyphenolics in wine and tea could also help in protecting the rest of the body from the additional complications of diabetes such as high blood pressure and heart disease. Diabetes places a stress on the entire body by increasing the production of free radicals, including molecules that react with oxygen, which degrade cellular function. Both red wine and tea contain antioxidants with proven health benefits, and have the potential to manage heart disease, high blood pressure and perhaps contribute to the prevention of cancer, which are all linked to free radicals.
"These results provide strong evidence for further studying the use of wine and tea to manage some stages of type 2 diabetes using animal models and clinical studies, and point to the importance of an antioxidant-rich diet as part of an overall management strategy," says Shetty. "This concept is not new, but we are finding clear cellular targets for the functions of dietary polyphenolics. Using specific beverage combinations could generate a whole food profile that has the potential to manage type 2 diabetes and its complications, especially in the early stages."
Source: University of Massachusetts Amherst