Abstract: The present invention relates to an ?-amylase activity inhibitor, and to food and beverages comprising the ?-amylase activity inhibitor. The ?-amylase activity inhibitor of the present invention exhibits remarkably excellent ?-amylase inhibitory activity as compared with guava extract. Accordingly, food and beverages containing the ?-amylase activity inhibitor are diet food and beverages suitable for people of high blood-sugar level or hyderlipidemia.

Abstract: The present invention relates to an &agr;-amylase activity inhibitor containing, as an effective component, polyphenols obtained through the following process: guava leaves and/or guava fruit are subjected to extraction with one or more solvents selected from among water and hydrophilic solvents; the resultant extract is subjected to ultrafiltration, to thereby remove substances having a molecular weight of less than 5,000; the remaining fraction is subjected to the butyl support hydrophobic chromatography. The elution (flow rate: 1 mL/min) of the sample was accomplished with the pH gradient by use of sodium dihydrogenphosphate and sodium phosphate solution (0.02 mol/L) and a fraction of the eluted substance is recovered, which fraction corresponds to the third single peak of an elution curve which is obtained when the absorbance of the substance is measured at 260 nm.