An extract of black, green, and mulberry teas causes malabsorption of carbohydrate but not of triacylglycerol in healthy volunteers

Background: In vitro studies suggest that extracts of black, green, and mulberry teas could interfere with carbohydrate and triacylglycerol absorption via their ability to inhibit α-amylase, α-glucosidase, sodium-glucose transporters, and pancreatic lipase. Objective: We measured breath hydrogen and ¹³CO₂ to investigate the ability of an extract of black, green, and mulberry tea leaves to induce malabsorption of carbohydrate and triacylglycerol in healthy volunteers. Design: In a crossover design, healthy adult volunteers randomly ingested test meals with a placebo beverage or a preparation containing an extract of black (0.1 g), green (0.1 g), and mulberry (1.0 g) teas. One test meal contained 50 g carbohydrate as white rice, 10 g butter, and 0.2 g [¹³C]triolein, and the beverages contained 10 g sucrose. The calorie content of the second test meal consisted entirely of lipid (30 g olive oil and 0.2 g [¹³C]triolein). Breath-hydrogen and ¹³CO₂ concentrations were assessed hourly for 8 h, and symptoms were rated on a linear scale. Results: With the carbohydrate-containing meal, the tea extract resulted in a highly significant increase in breath-hydrogen concentrations, which indicated appreciable carbohydrate malabsorption. A comparison of hydrogen excretion after the carbohydrate-containing meal with that after the nonabsorbable disaccharide lactulose suggested that the tea extract induced malabsorption of 25% of the carbohydrate. The tea extract did not cause triacylglycerol malabsorption or any significant increase in symptoms. Conclusion: This study provides the basis for additional experiments to determine whether the tea extract has clinical utility for the treatment of obesity or diabetes.