|One serving of most commercial micellar casein products contains 400mg of highly bioavailable calcium.|
The reason Gonzales et al.'s study made the cut is that it was the first study to assess the joint and individual effects of protein and calcium in a preload on subsequent compensation of energy intake while assessing both subjective and objective measures of appetite.
More specifically, the scientists recruited 20 normal and overweight subjects (12 men and 8 women | BMI between 18.5 and 29.9 kg/m²) who arrived at the laboratory for each of the actual testing sessions after an overnight fast.
"An intravenous catheter was inserted into an antecubital vein and, after a baseline blood sample and visual analog scale (VAS), participants consumed one of 4 preloads (CON, PRO, CAL, or PROCAL). A timer was started when participants consumed the first mouthful of the preload, after which blood samples and a VAS were taken at 15, 30, 45, and 60 min post-preload. Food intake was then assessed (60 min after preload ingestion) by providing participants with a homogenous pasta meal, which they were asked to consume until "comfortably full."
Table 1: Nutritional composition of preloads | CAL, high-calcium preload; CON, low-calcium and lowprotein control preload; PRO, high-protein preload; PROCAL, high-protein and highcalcium preload (Gonzalez. 2015).
The mass of food consumed was then converted into energy intake taking into account water losses from reheating. The time frame after the preload was based on our previous findings in which appetite sensations after a high-calcium breakfast were divergent within the first 60 min of the postprandial period (Gonzalez. 2013 & 2014). Participants were initially served a subserving of the whole portion, which was augmented at regular intervals. This method prevents participants from feeling overwhelmed by a whole, large portion of pasta while never allowing the serving bowl to be empty, thus preventing participants from stopping eating because they reached the end of a ‘‘portion.’All preloads contained instant porridge oats (Oatso Simple Golden Syrup, Quaker Oats UK) and water to provide 0.5 g carbohydrate/kg body mass. These were cooked in a microwave for 2 min at 1000 W and cooled for 5 min before being served.
- For CAL trials, a milk-extracted calcium powder [Capolac, Arla Foods Ingredients; from the same batch that was validated independently previously (18)] was added to the porridge to increase the calcium content by 15 mg/kg body mass.
- For PRO trials, milk protein concentrate (MyProtein.co.uk) was added to increase the protein content of the porridge by 0.35 g/kg body mass.
|Figure 1: Appetite scores and energy compensation =""less energy intake relative to the energy in the preload" and thus probably a lower total food intake in a real world scenario (Gonzalez. 2015).|
|Figure 2: Plasma insulin (left), GIP1–42 (right) postprandial time-averaged (60 min) AUCs after CONs, PROs, CALs, or PROCALs consumed by healthy adults (Gonzalez. 2015).|
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- Gonzalez, Javier T., Penny LS Rumbold, and Emma J. Stevenson. "Appetite sensations and substrate metabolism at rest, during exercise, and recovery: impact of a high-calcium meal." Applied Physiology, Nutrition, and Metabolism 38.12 (2013): 1260-1267.
- Gonzalez, Javier T., and Emma J. Stevenson. "Calcium co-ingestion augments postprandial glucose-dependent insulinotropic peptide1–42, glucagon-like peptide-1 and insulin concentrations in humans." European journal of nutrition 53.2 (2014): 375-385.
- Gonzalez, Javier T., et al. "Calcium Ingestion Suppresses Appetite and Produces Acute Overcompensation of Energy Intake Independent of Protein in Healthy Adults." The Journal of Nutrition (2015): jn-114.
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