Time Courses of Gastric Volume and Content After Different Types of Casein Ingestion in Healthy Men: A Randomized Crossover Study
Yasuyuki Sakata, The Journal of Nutrition, 22 July 2022
Background
Few studies have evaluated differences in the curd-forming ability of casein on gastric volume and content directly after ingestion in humans.
Objectives
This study evaluated the time course of gastric volume and curd conditions in the stomach after protein ingestion.
Methods
This was an open-labeled, randomized crossover trial. Ten healthy men (age: 33.4 ± 7.3 y; body mass index: 21.9 ± 0.9 kg/m2) received 350 g of three isonitrogenous and isocaloric protein drinks containing 30 g of micellar casein (MCN), sodium caseinate (SCN), or whey protein concentrate (WPC). The gastric antrum cross-sectional area (CSA) and curd in the stomach were measured using ultrasonography within 5 h after ingestion. The differences between test foods were tested using the MIXED model and post-hoc tests using Fisher's protected least significant difference.
Results
The incremental area under the curve of the gastric antrum CSA after MCN ingestion was 1.3-fold and 1.5-fold higher than that after the ingestion of SCN and WPC, respectively (both P < 0.05), but not different between SCN and WPC. The number of participants with curds of ≥ 20 mm with a high echogenicity clot observed in the stomach within 5 h after MCN ingestion was significantly greater than that after the ingestion of other proteins (n = 9 for MCN, n = 2 for SCN, and n = 0 for WPC, both P < 0.01). The regression line slopes on total plasma amino acid concentration and gastric antrum CSA were significantly different between the participants with and without curds.
Conclusion
In contrast to SCN and WPC, MCN ingestion resulted in slow kinetics of gastric antrum CSA. Differences in curd formation in the stomach affect gastric emptying and plasma amino acid absorption kinetics after casein ingestion in healthy men.