Clinical Research Directory

Milk Beta Caseins on Digestive Discomfort, Gastric Emptying

A1 and A2 β-casein are genetic variants of β-casein in cow's milk that differ by a single amino acid at position 67. Digestion of A1 β-casein may result in greater release of beta-casomorphin-7 (BCM-7), an opioid peptide that may influence gastrointestinal function. Previous work from our group in lactose maldigesters found differences in gastric emptying following consumption of A1/A2 milk compared with A1 protein-free (A1PF) milk. This randomized, masked, crossover study evaluated whether opioid receptor blockade with oral naloxone influenced gastric emptying following consumption of A1/A2 milk compared with A1PF milk in lactose maldigesters. Participants consumed each milk treatment with 2 mg oral naloxone during separate study visits. Gastric volume was measured using magnetic resonance imaging (MRI) over 120 minutes, and gastrointestinal symptoms were assessed. The study was designed to investigate whether opioid receptor signaling contributes to differences in gastric emptying between A1/A2 milk and A1PF milk.