I fucking warned you Brian...
Opioid drugs interact with three classes of opioid receptors: mu opioid receptors (MOR), delta opioid receptors (DOR) and kappa opioid receptors (KOR), but opioid drugs mostly target the MORs.
The µ-opioid receptors are activated in the wall of the stomach and the small and large intestine by both endogenous (e.g. enkephalins, endorphins and dynorphins) and exogenous (e.g. morphine, oxycodone, methadone) opioids and modify GI function.
Activation of opioid receptors in the submucosa inhibits water and electrolyte secretion into the gut lumen and increases fluid absorption from the intestine and blood flow in the gut wall.
Chymotrypsin and trypsin break proteins down to tripeptides, dipeptides, and individual amino acids. The cells that line the small intestine release additional enzymes that also contribute to the enzymatic digestion of polypeptides. Tripeptides, dipeptides, and single amino acids enter the enterocytes of the small intestine using active transport systems, which require ATP. Once inside, the tripeptides and dipeptides are all broken down to single amino acids, which are absorbed into the bloodstream.
Submucosal secretomotor neurons release acetylcholine and VIP, which activate muscarinic and VIP receptors on the basolateral surface of the enterocytes, which can activate epithelial cell chloride channels. Chloride moves from the enterocyte cytoplasm into the gut lumen. H2O follows chloride via an osmotic mechanism. Opioid drugs activating MOR and DOR on secretomotor neurons suppress acetylcholine and VIP release, resulting in a decrease in chloride secretion and osmotic water movement.
The resultant reduction of osmotic water movement has an inhibitory effect on the di and tripeptides being shuttled into the bloodstream
But wait....because you said it "slows digestion down" it absolutely means you absorb more nutrients. Idiot druggie