Effects of physical form of β-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 calcium to aggregate or native forms of β-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 4 trials in a randomised, double-blind, crossover design. Participants consumed test drinks consisting of 30 g β-lactoglobulin in a native form with (NATIVE+MINERALS) and without (NATIVE) a calcium-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 13 C-acetate and 13 C-octanoate, and energy intake was assessed with an ad libitum meal at 120 min. A protein*mineral interaction effect was observed for total glucagon-like peptide-1 (GLP-1 TOTAL ) incremental area under the curve (iAUC; p <0.01) whereby MINERALS+AGGREG increased GLP-1 TOTAL iAUC to a greater extent than AGGREG (1882±603 vs 1550±456 pmol·L -1 ·120 min, p <0.01), but MINERALS+NATIVE did not meaningfully alter the GLP-1 iAUC compared with NATIVE (1669±547 vs 1844±550 pmol·L -1 ·120 min, p =0.09). A protein*minerals interaction effect was also observed for gastric emptying half-life ( p <0.01) whereby MINERALS+NATIVE increased gastric emptying half-life compared with NATIVE (83±14 vs 71±8 min, p <0.01), whereas no meaningful differences were observed between MINERALS+AGGREG vs AGGREG ( p =0.70). These did not result in any meaningful changes in energy intake (protein*minerals interaction, p = 0.06). These data suggest that the potential for calcium to stimulate GLP-1 secretion at moderate protein doses may depend on protein form. This study was registered at clinicaltrials.gov (NCT04659902).