A material with opioid activity in bovine milk and milk products.

Chloroform-methanol extracts of lyophilized milk, of commercially available dried milk or baby food and of casein digests were tested for opioid activity on the guinea-pig ileum longitudinal muscle-myenteric plexus preparation. Compounds with opioid activity--which proved to be resistant to peptidases--were detected in certain batches of baby food, casein digest, and cow milk in considerably varying amounts.