Development of a dynamic in vitro gastric digestion protocol for acid suppression and evaluation of starch and protein digestion in three protein-based meals.

Abstract

Acid suppression therapy alters gastric pH which may influence food digestion. However, its impact on the digestion behavior of food matrices with varying composition remains unclear. This study compared the in vitro digestion of three sandwiches with varying protein sources (whey, egg white, or almond) against bread as a control. To represent healthy adult conditions, simulated gastric juice pH was set to 0.8 with a secretion rate dependent on intragastric pH. For acid suppression conditions, gastric juice pH was set to 1.8 with a static secretion rate equivalent to 50% of the healthy adult secretion volume to maintain intragastric pH above 4. Overall, digestion kinetics were influenced by gastric condition. Gastric starch hydrolysis after 180 min was significantly higher (p = 0.0002) under acid suppression (53 ± 13%) compared to the healthy adult condition (38 ± 17%) across all meals. This likely reflects reduced salivary α-amylase inactivation due to elevated intragastric pH. Protein hydrolysis remained low during the gastric phase for all meals (average of protein meals was 8 ± 1%, bread meal was 23 ± 2% across both conditions). However, after static small intestinal digestion, total starch hydrolysis was similar between digestion conditions, whereas total protein hydrolysis was significantly higher (p = 0.0023) under the healthy adult condition (94.2 ± 8.1%) compared with acid suppression (84.7 ± 5.1%) average across all meals. These findings highlight the effects of acid suppression on in vitro digestion behavior, and the importance of including both gastric and small intestinal phases to understand overall nutrient hydrolysis.