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One serving of most commercial micellar casein products contains 400mg of highly bioavailable calcium. |
As a
SuppVersity reader you won't be surprised to hear that Gonzalez et al. found that the addition of
calcium to a meal suppresses appetite and reduces the energy intake on a subsequent meal. The fact that the latest study from the Northumbria University still made the
SuppVersity news is
not the appetite reducing effect per se.
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.
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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.
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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). |
"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."
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.
To
test the synergy of protein and calcium, the PROCAL was composed of
the addition of protein and calcium in identical absolute quantities to the PRO and CAL trials (Table 1). The calcium concentration of the
drinking water used to make the porridge was determined in duplicate
with the use of a photometric technique (Modular P, Roche Diagnostics).
This was determined as 0.82
+/- 0.01 mmol/L (given an atomic mass of
40.078 g/mol, this equates to 3.27
+/- 0.03 mg/dL) and was taken into
account in the calcium content of the preloads (Table 1).
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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). |
All the effort was obviously worth it: The results in
Figure 1 are interesting... to say the least. As you can see, the energy intake after the PROCAL (3419 +/- 345 kJ; P < 0.05) was significantly less than after the CON (4126 6 +/- 395 kJ), but not after the PRO (3699 +/- 304 kJ; P > 0.05) or CAL (3501 +/- 253 kJ; P > 0.05). More importantly, however, the energy compensation was significantly greater (overcompensation) with the CAL vs. the PRO (P < 0.01) (Figure 1) and tended to be greater with the PROCAL vs. the PRO (P = 0.06).
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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). |
The latter is significant, since a higher over-compensation (in this study) was defined as "
less energy intake relative to the energy in the preload" (Gonzalez. 2015) and does thus signify a greater usefulness during dieting. An effect that can easily be explained by the low insulin and GIP and levels the scientists observed in the CAL trial (
Figure 2).
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Read the previous SuppVersity Classic on the fat loss benefits of calcium: Higher Calcium Intake Greater Fatty Acid Oxidation!? True: Chronic & Acute Effect Size Comparable to Caffeine | read the full article |
Bottom line: Overall, the study results do thus confirm that it's the calcium content and not, as scientists have previously suspected the high protein content of many high calcium foods that affects the appetite and - more importantly - leads to relatively lower food intakes on subsequent meal. This effect is - that's at least what the hormonal response would suggest - mediated by reduced insulin and GIP responses to the high calcium meals and coincides with the subjective appetite response of the subjects. In addition it may be amplified by delayed gastric emptying (Shafer. 1985), and changes in other gastrointestinal hormones such as cholecystokinin (Nakajima. 2012), peptide YY (Mace.2012), and gastrin (Behar. 1977) as they have been observed in previous studies on high calcium foods.
Practically speaking, a higher calcium intake will thus help you to stick to your diet with higher protein intakes having no significant additive, but no inhibitory effect either |
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References:
- Behar, J., M. Hitchings, and R. D. Smyth. "Calcium stimulation of gastrin and gastric acid secretion: effect of small doses of calcium carbonate." Gut 18.6 (1977): 442-448.
- 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.
- Mace, Oliver J., Marcus Schindler, and Sonal Patel. "The regulation of K‐and L‐cell activity by GLUT2 and the calcium‐sensing receptor CasR in rat small intestine." The Journal of physiology 590.12 (2012): 2917-2936.
- Nakajima, Shingo, Tohru Hira, and Hiroshi Hara. "Calcium‐sensing receptor mediates dietary peptide‐induced CCK secretion in enteroendocrine STC‐1 cells." Molecular nutrition & food research 56.5 (2012): 753-760.
- Shafer, R. B., et al. "Do calories, osmolality, or calcium determine gastric emptying?." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 248.4 (1985): R479-R483.