Cereal‐derived phenolic compounds, peptides, nonstarch polysaccharides, and lipids have been shown to inhibit α‐amylase and α‐glucosidase activities. The barley alpha-amylase/subtilisin inhibitor (BASI) can inhibit the barley alpha-amylase 2 (AMY2) and subtilisin-type serine proteases. BASI belongs to the Kunitz-type trypsin inhibitor family of the beta-trefoil fold proteins.