Effects of physical form of -lactoglobulin and calcium ingestion on GLP-1 secretion, gastric emptying and energy intake in humans: a randomised crossover trial.

The aim of this study was to assess whether adding Ca to aggregate or native forms of -lactoglobulin alters gut hormone secretion, gastric emptying rates and energy intake in healthy men and women. Fifteen healthy adults (mean ± sd: 9M/6F, age: 24 ± 5 years) completed four trials in a randomised, double-blind, crossover design. Participants consumed test drinks consisting of 30 g of -lactoglobulin in a native form with (NATIVE + MINERALS) and without (NATIVE) a Ca-rich mineral supplement and in an aggregated form both with (AGGREG + MINERALS) and without the mineral supplement (AGGREG). Arterialised blood was sampled for 120 min postprandially to determine gut hormone concentrations. Gastric emptying was determined using C-acetate and C-octanoate, and energy intake was assessed with an meal at 120 min. A protein × mineral interaction effect was observed for total glucagon-like peptide-1 (GLP-1) incremental AUC (iAUC; < 0·01), whereby MINERALS + AGGREG increased GLP-1 iAUC to a greater extent than AGGREG (1882 ± 603 . 1550 ± 456 pmol·l·120 min, < 0·01), but MINERALS + NATIVE did not meaningfully alter the GLP-1 iAUC compared with NATIVE (1669 ± 547 . 1844 ± 550 pmol·l·120 min, = 0·09). A protein × minerals interaction effect was also observed for gastric emptying half-life ( < 0·01) whereby MINERALS + NATIVE increased gastric emptying half-life compared with NATIVE (83 ± 14 . 71 ± 8 min, < 0·01), whereas no meaningful differences were observed between MINERALS + AGGREG . AGGREG ( = 0·70). These did not result in any meaningful changes in energy intake (protein × minerals interaction, = 0·06). These data suggest that the potential for Ca to stimulate GLP-1 secretion at moderate protein doses may depend on protein form. This study was registered at clinicaltrials.gov (NCT04659902).