Wine and tea compounds linked to diabetes benefits

By Stephen Daniells

- Last updated on GMT

Related tags Red wine Tea Blood sugar

Antioxidant-rich red wine and tea could help regulate blood sugar
levels in diabetics, suggests a new study from the University of

Red wine might inhibit the activity of alpha-glucosidase, an enzyme responsible for triggering the absorption of glucose by the small intestine, by almost 100 per cent, according to the new laboratory study (in vitro​) published in the Journal of Food Biochemistry​. The researchers also note that, out of four kinds of tea tested, black tea extracts showed the highest activity for inhibiting the enzyme. Importantly, the Massachusetts-based researchers report no effect on the activity of alpha-amylase, an enzyme responsible for starch metabolism, and an undesirable effect observed with some medications used to control blood sugar. "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,"​ said lead researcher Kalidas 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." Study details ​ Shetty, working with Young-In Kwon and Emmanouil Apostolidis, took four random samples of red and white wine, and extracts from four types of tea (black, oolong, white and green teas). Laboratory tests focussed on the alpha-glucosidase enzyme, already used as a target for some current drugs used to treat type-2 diabetes, and tested the wines and tea extracts. The same concentration was also tested for alpha-amylase activity. The researchers report that red wine inhibited alpha-glucosidase by almost 100 per cent, while inhibition of the enzyme by white wines was only about 20 per cent when 500 microlitres were used. A dose-dependent effect for the teas was observed, with black tea extracts possessing the highest effect on alpha-glucosidase inhibition (over 90 per cent at a concentration of 200 micrograms per millilitre), followed by white tea and oolong tea (87 and 80 per cent, respectively, at a concentration of 200 micrograms per millilitre). The effects were related to the concentration of polyphenolics, said the researchers. "Our testing showed that red wine contains roughly ten times more polyphenolics than white wine,"​ said 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.""The major phenolic components of red wine are caffeic acid, coumaric acid, gallic acid and quercetin, and of tea are protocatechuic acid, caffeic acid, coumaric acid and gallic acid,"​ stated the researchers. "These phenolic compounds were linked to high alpha-glucosidase inhibitory activity,"​ they added. Furthermore, small or negligible effects on alpha-amylase activity were recorded by the researchers. Take-home message "It is clear that some wine and tea types have high antioxidant activity and good inhibitory profiles on carbohydrate-modulating enzymes related to glucose absorption in the intestine,"​ stated the researchers. "The potential for managing both glucose absorption and cellular redox dysfunction for preventing postprandial hyperglycemia linked to type 2 diabetes and hyperglycemia-induced vascular complications leading to hypertension can be designed in part through food systems, and provides the basis for clinical studies." Independent comment ​ Dr Victoria King, research manager at Diabetes UK, told "This is an interesting study but it only looks at a limited sample of teas and red wines. It showed that in a 'test tube' situation some of those beverages were able to inhibit, to varying degrees, a protein called alpha-glucosidase, which is responsible for triggering the take-up of glucose by the small intestine. "It is too early to tell how this research would actually translate into clinical benefits for people with diabetes. We certainly wouldn't recommend that people with Type 2 diabetes increase their intake of tea and red wine to treat their condition. "However, eating a healthy balanced diet and taking regular physical activity will help people with diabetes control their blood glucose levels and reduce their risk of serious complications such as heart disease and stroke."​ An estimated 19 million people are affected by diabetes in the EU 25, equal to four per cent of the total population. This figure is projected to increase to 26 million by 2030. In the US, there are over 20 million people with diabetes, equal to seven per cent of the population. The total costs are thought to be as much as $132 billion, with $92 billion being direct costs from medication, according to 2002 American Diabetes Association figures. Source: Journal of Food Biochemistry​ (Blackwell Publishing) Volume 32, Number 1, Pages 15-31, doi:10.1111/j.1745-4514.2007.00165.x "Inhibitory potential of wine and tea against alpha-amylase and alpha-glucosidase for management of hyperglycemia linked to type-2 diabetes" ​Authors: Y.-I. Kwon, E. Apostolidis, K. Shetty

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