Relationship between polyphenol intake and blood glucose response of normal and diabetic individuals.

Five leguminous and eight nonleguminous foods were analyzed for polyphenol concentration by the Prussian Blue and the Folin Denis methods and correlated with blood glucose response (glycemic index) in normal or diabetic volunteers. Polyphenol concentrations and intakes per 50 g available carbohydrate portions were higher in the leguminous foods than those in the nonleguminous foods. In both normal and diabetic individuals, a negative correlation was observed between glycemic index and the concentration or total intake of polyphenols. Polyphenols, especially the large polymeric type or condensed tannins, appear to be responsible in part for the reduced glycemic response to carbohydrate foods and in part to lower blood glucose response to legumes compared with cereal products.