Calcium ingestion suppresses appetite and produces acute overcompensation of energy intake independent of protein in healthy adults

Background: Prior evidence suggests high-calcium intake influences postprandial appetite and insulinemia, possibly due to elevated incretins. In vitro and ex vivo models demonstrate extracellular calcium and protein synergistically enhance secretion of incretins. This is yet to be shown in humans. Objective: This study was designed to assess energy intake compensation in response to protein and calcium ingestion. Design: Twenty healthy adults (13 men; 7 women) completed 4 trials in a randomized double-blind, crossover design, separated by ≥ 48 h. During trials, participants consumed preloads which were low in protein and calcium (CON; 4 g and 104 mg, respectively), high in protein (PRO; 29 g), high in calcium (CAL; 1170 mg) or high in both protein and calcium (PROCAL). Blood samples were collected at baseline, and 15, 30, 45 and 60 min following preload ingestion, to determine insulin and incretin hormone concentrations. Energy intake was assessed by a homogenous test-meal 60 min after the preload. Visual analogue scales were completed immediately before blood sampling to assess subjective appetite sensations. Results: Relative to CON, PRO produced 100% (95% CI: 85, 115%) energy compensation, whereas CAL produced significant overcompensation 118% (95% CI: 104, 133%), which was significantly more positive than PRO (P < 0.05). PROCAL resulted in energy compensation of 109% (95% CI: 95, 123%), which tended to be greater than PRO (P = 0.06). The mean difference in appetite sensations relative to CON was not significantly different between PRO (-3; 95% CI: -8 to 3 mm), CAL (-5; 95% CI: -9 to 0) and PROCAL (-5; 95% CI: -10 to -1; P > 0.05). Conclusions: The addition of protein to a preload results in almost perfect energy compensation, whereas addition of calcium, with or without protein suppresses appetite and produces over compensation of subsequent energy intake. The role of circulating insulin and incretin concentrations in these responses however, remain unclear. Registered at clinicaltrials.gov: NCT01986036. Keywords: females; food intake; fullness; glucagon-like peptide-1; hunger; insulin; males; protein.