1. The aim of the present study was to determine whether oral ingestion of raw soya-bean flour, which contains trypsin inhibitors, alters the release of cholecystokinin (CCK) in man.
2. Eleven healthy volunteers ate two mixed meals: one with raw soya-bean flour and the other with soya-bean flour that had been heat-treated. The two flours inhibited 34 and 3 mg trypsin/g flour respectively.
3. CCK was measured in plasma using a bioassay based on the release of amylase (EC 184.108.40.206) from dispersed rat pancreatic acini.
4. The peak CCK response was 168 (SE 8.1) pmol/l with raw soya-bean flour but 4.9 (SE 2.8) pmol/l with heat-treated flour (P < 0.05).
5. We conclude that ingestion of raw soya-bean flour increases CCK release in man and that heat treatment which reduces the trypsin inhibitor content of the flour also diminishes its CCK-releasing effect.