The insulinogenic effect of whey protein is partially mediated by a direct effect of amino acids and GIP on β-cells.
Level 5 - mechanism / opinion, no new human data
In vitro laboratory study on isolated rodent islets using human serum samples
PubMed 22647249 · doi:10.1186/1743-7075-9-48
What was done
Isolated mouse Langerhans islets were incubated with postprandial serum collected from healthy individuals after consuming carbohydrate-equivalent meals of whey protein or white wheat bread. The researchers also tested the direct effects of specific amino acid combinations (isoleucine, leucine, valine, lysine, and threonine), GIP, and a GIP receptor antagonist ((Pro(3))GIP[mPEG]) on islet insulin release.
What was found
Whey ingestion produced higher postprandial amino acids, GIP, and GLP-1 responses than white wheat bread. Whey serum from 15 and 30 minutes postprandially increased islet insulin secretion by +87% and +139%, respectively, compared to control bread serum (P < 0.05). The 5-amino-acid mixture stimulated insulin secretion by +270% (P < 0.05), which increased to +558% with the addition of GIP (P < 0.05 vs. glucose). The GIP receptor antagonist reduced whey serum-stimulated insulin secretion by -56% at 15 minutes and -59% at 30 minutes (P < 0.05).
Why it matters
This study provides direct mechanistic evidence that postprandial hyperinsulinemia following whey consumption is mediated by the combined, direct action of elevated branched-chain/essential amino acids and GIP on pancreatic beta-cells.
Limits
The abstract does not report the number of human serum donors. The primary mechanistic findings are derived from in vitro static incubations of isolated mouse islets rather than intact human physiological systems or human islets.
Cited by
- supports Consuming large amounts of whey protein stimulates an insulin response driven by essential and branched-chain amino acids that suppresses ketosis.