Benjamin P. Green

Short communication: Patterns of dairy consumption in free-living children and adolescents

According to national survey data, dairy food consumption has fallen in recent years and declines further with age, especially from childhood to adolescence. Dietary surveys typically rely on retrospective dietary assessment methods and use broad age groupings (4-10 yr; 11-18 yr), making it challenging to differentiate between middle-childhood and adolescence. Consequently, there is a need to assess dairy food consumption during middle-childhood and adolescence using more robust dietary assessment tools. Therefore, the present study aimed to describe and compare patterns of dairy consumption throughout middle-childhood and adolescence. Dairy food consumption was assessed during school term-time over 4 consecutive days, including 2 weekdays and 2 weekend days, in a sample of free-living children (9-11 yr, n=40) and adolescents (15-18 yr, n=35). For children, free-living dairy intake was evaluated through parental-weighed food records, and for adolescents, a combined weighed self-reported food record and 24-h dietary recall technique was utilized. Food records were explored to determine types, amounts, and frequency of dairy food consumption, and were analyzed for differences between middle-childhood and adolescence using a between group 2×2 (age×sex) ANOVA. Descriptive data suggested that milk was the most popular dairy product consumed by both children and adolescents. Statistical analysis revealed a main effect for sex on total milk consumption (mL) and number of daily milk portions consumed. No interaction or main effect was present for any other variable. The present study indicates that independent of age, boys consumed greater amounts of milk compared with girls. Contrary to existing literature, findings suggest no difference in milk-based dairy consumption between middle-childhood and adolescence.

Calcium Ingestion Suppresses Appetite and Produces Acute Overcompensation of Energy Intake Independent of Protein in Healthy Adults

BACKGROUND Prior evidence suggests that high-calcium intake influences postprandial appetite and insulinemia, possibly due to elevated incretins. In vitro and ex vivo models demonstrate that 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. METHODS Twenty healthy adults (13 men; 7 women) completed 4 trials in a randomized, double-blind crossover design separated by ≥48 h. During the trials, each participant consumed a low-calcium and low-protein control preload [(CON); 4 g and 104 mg, respectively], a high-protein preload (PRO; 29 g), a high-calcium preload (CAL; 1170 mg), or a high-protein and high-calcium preload (PROCAL). Blood samples were collected at baseline and 15, 30, 45, and 60 min after preload ingestion to determine insulin and incretin hormone concentrations. Energy intake was assessed by a homogenous test meal 60 min after the preload. Visual analog scales were completed immediately before blood sampling to assess subjective appetite sensations. RESULTS Relative to the CON, the PRO produced 100% (95% CI: 85%, 115%) energy compensation, whereas the CAL produced significant overcompensation [118% (95% CI: 104%, 133%)], which was significantly more positive than with the PRO (P < 0.05). The PROCAL resulted in energy compensation of 109% (95% CI: 95%, 123%), which tended to be greater than with the PRO (P = 0.06). The mean difference in appetite sensations relative to the CON was not significantly different between the PRO (-3 mm; 95% CI: -8, 3 mm), CAL (-5 mm; 95% CI: -9, 0 mm), and PROCAL (-5 mm; 95% CI: -10, -1 mm) (P > 0.05). CONCLUSIONS The addition of protein to a preload results in almost perfect energy compensation, whereas the addition of calcium, with or without protein, suppresses appetite and produces overcompensation of subsequent energy intake. The role of circulating insulin and incretin concentrations in these responses, however, remains unclear. This trial was registered at clinicaltrials.gov as NCT01986036.

The Effect of a Dairy-Based Recovery Beverage on Post-Exercise Appetite and Energy Intake in Active Females.

This study was designed to assess the effect of a dairy-based recovery beverage on post-exercise appetite and energy intake in active females. Thirteen active females completed three trials in a crossover design. Participants completed 60 min of cycling at 65% V̇O2peak, before a 120 min recovery period. On completion of cycling, participants consumed a commercially available dairy-based beverage (DBB), a commercially available carbohydrate beverage (CHO), or a water control (H2O). Non-esterified fatty acids, glucose, and appetite-related peptides alongside measures of subjective appetite were sampled at baseline and at 30 min intervals during recovery. At 120 min, energy intake was assessed in the laboratory by ad libitum assessment, and in the free-living environment by weighed food record for the remainder of the study day. Energy intake at the ad libitum lunch was lower after DBB compared to H2O (4.43 ± 0.20, 5.58 ± 0.41 MJ, respectively; p = 0.046; (95% CI: −2.28, −0.20 MJ)), but was not different to CHO (5.21 ± 0.46 MJ), with no difference between trials thereafter. Insulin and GLP-17-36 were higher following DBB compared to H2O (p = 0.015 and p = 0.001, respectively) but not to CHO (p = 1.00 and p = 0.146, respectively). In addition, glucagon was higher following DBB compared to CHO (p = 0.008) but not to H2O (p = 0.074). The results demonstrate that where DBB consumption may manifest in accelerated recovery, this may be possible without significantly affecting total energy intake and subsequent appetite-related responses relative to a CHO beverage.

The influence of calcium supplementation on substrate metabolism during exercise in humans: a randomized controlled trial

Background/Objectives:High calcium intakes enhance fat loss under restricted energy intake. Mechanisms explaining this may involve reduced dietary fat absorption, enhanced lipid utilization and (or) reductions in appetite. This study aimed to assess the impact of 2 weeks of calcium supplementation on substrate utilization during exercise and appetite sensations at rest.Subjects/Methods:Thirteen physically active males completed two 14-d supplemental periods, in a double-blind, randomized crossover design separated by a ⩾4-week washout period. During supplementation, a test-drink was consumed daily containing 400 and 1400 mg of calcium during control (CON) and high-calcium (CAL) periods, respectively. Cycling-based exercise tests were conducted before and after each supplemental period to determine substrate utilization rates and circulating metabolic markers (non-esterified fatty acid, glycerol, glucose and lactate concentrations) across a range of exercise intensities. Visual analog scales were completed in the fasting, rested state to determine subjective appetite sensations.Results:No significant differences between supplements were observed in lipid or carbohydrate utilization rates, nor in circulating metabolic markers (both P>0.05). Maximum rates of lipid utilization were 0.47±0.05 and 0.44±0.05 g/min for CON and CAL, respectively, prior to supplementation and 0.44±0.05 and 0.42±0.05 g/min, respectively, post-supplementation (main effects of time, supplement and time x supplement interaction effect all P>0.05). Furthermore, no significant differences were detected in any subjective appetite sensations (all P>0.05).Conclusions:Two weeks of calcium supplementation does not influence substrate utilization during exercise in physically active males.

Agreement between fingertip-capillary and antecubital-venous appetite-related peptides

This study examined the agreement between fingertip-capillary and antecubital-venous measures of appetite-related peptides. Simultaneous fingertip-capillary and antecubital-venous blood samples were collected from 19 participants. The samples were obtained at baseline, 30, 60, 90, and 120 min following breakfast for the determination of plasma GLP17-36, glucagon, insulin and leptin. Between-day reproducibility of fingertip-capillary-derived estimates was assessed in 18 participants. Deming regression, limits of agreement (LOA) and typical error as a coefficient of variation (CV) were used to quantify agreement (CVa) and reproducibility (CVr). Deming regression revealed no systematic bias for any of the analytes studied, but for insulin there was evidence of a proportional difference at higher concentrations. Measures of GLP17-36 (CVa=24.0%, LOA ±2.5 pg m/l per h), leptin (CVa=9.0%, LOA ×/÷1.19) and glucagon (CVa=21.0%, LOA, ±31.5 pg m/l per h) revealed good agreement between methodological approaches. Fingertip-capillary glucagon was highly reproducible between days (CVr=8.2%). GLP17-36 and leptin demonstrated modest reproducibility (CVr=22.7 and 25.0% respectively). For insulin, agreement (CVa=36.0%, LOA ×/÷1.79) and reproducibility were poor (CVr=36.0%). Collectively, the data demonstrate that fingertip-capillary blood sampling provides a comparable and reproducible alternative to antecubital-venous blood sampling for the quantification of glucagon, and to a lesser extent for GLP17-36 and leptin. Caution should be exercised when utilising fingertip-capillary blood sampling for insulin quantification, and consequently should not be employed interchangeably with antecubital-venous blood sampling.

Comparison of short-term energy intake and appetite responses to active and seated video gaming, in 8-11-year-old boys.

The acute effects of active and seated video gaming on energy intake (EI), blood glucose, plasma glucagon-like peptide-1 (GLP-17-36) and subjective appetite (hunger, prospective food consumption and fullness) were examined in 8-11-year-old boys. In a randomised, crossover manner, twenty-two boys completed one 90-min active and one 90-min seated video gaming trial during which food and drinks were provided ad libitum. EI, plasma GLP-17-36, blood glucose and subjective appetite were measured during and following both trials. Time-averaged AUC blood glucose was increased (P=0·037); however, EI was lower during active video gaming (1·63 (sem 0·26) MJ) compared with seated video gaming (2·65 (sem 0·32) MJ) (P=0·000). In a post-gaming test meal 1 h later, there were no significant differences in EI between the active and seated gaming trials. Although estimated energy expenditure was significantly higher during active video gaming, there was still no compensation for the lower EI. At cessation of the trials, relative EI (REI) was significantly lower following active video gaming (2·06 (sem 0·30) MJ) v. seated video gaming (3·34 (sem 0·35) MJ) (P=0·000). No significant differences were detected in time-averaged AUC GLP-17-36 or subjective appetite. At cessation of the active video gaming trial, EI and REI were significantly less than for seated video gaming. In spite of this, the REI established for active video gaming was a considerable amount when considering the total daily estimated average requirement for 8-11-year-old boys in the UK (7·70 MJ).

Acute effects of active gaming on ad libitum energy intake and appetite sensations of 8-11-year-old boys

The present study examined the acute effects of active gaming on energy intake (EI) and appetite responses in 8-11-year-old boys in a school-based setting. Using a randomised cross-over design, twenty-one boys completed four individual 90-min gaming bouts, each separated by 1 week. The gaming bouts were (1) seated gaming, no food or drink; (2) active gaming, no food or drink; (3) seated gaming with food and drink offered ad libitum; and (4) active gaming with food and drink offered ad libitum. In the two gaming bouts during which foods and drinks were offered, EI was measured. Appetite sensations - hunger, prospective food consumption and fullness - were recorded using visual analogue scales during all gaming bouts at 30-min intervals and at two 15-min intervals post gaming. In the two bouts with food and drink, no significant differences were found in acute EI (MJ) (P=0·238). Significant differences were detected in appetite sensations for hunger, prospective food consumption and fullness between the four gaming bouts at various time points. The relative EI calculated for the two gaming bouts with food and drink (active gaming 1·42 (sem 0·28) MJ; seated gaming 2·12 (sem 0·25) MJ) was not statistically different. Acute EI in response to active gaming was no different from seated gaming, and appetite sensations were influenced by whether food was made available during the 90-min gaming bouts.

The between-day reproducibility of fasting, satiety-related analytes, in 8 to 11 year-old boys

The aim of the present study was to establish the between-day reproducibility of fasting plasma GLP-17-36, glucagon, leptin, insulin and glucose, in lean and overweight/obese 8-11year-old boys. A within-group study design was utilised wherein the boys attended two study days, separated by 1week, where a fasting fingertip capillary blood sample was obtained. Deming regression, mean difference, Bland-Altman limits of agreement (LOA) and typical imprecision as a percentage coefficient of variation (CV %), were utilised to assess reproducibility between-days. On a group level, Deming regression detected no evidence of systematic or proportional bias between-days for all of the satiety-related analytes however, only glucose and plasma GLP-17-36 displayed low typical and random imprecision. When analysed according to body composition, good reproducibility was maintained for glucose in the overweight/obese boys and for plasma GLP-17-36, in those with lean body mass. The present findings demonstrate that the measurement of glucose and plasma GLP-17-36 by fingertip capillary sampling on a group level, is reproducible between-days, in 8-11year-old boys. Comparison of blood glucose obtained by fingertip capillary sampling can be made between lean and overweight/obese 8-11year-old boys. Presently, the comparison of fasting plasma GLP-17-36 according to body weight is inappropriate due to high imprecision observed in lean boys between-days. The use of fingertip capillary sampling in the measurement of satiety-related analytes has the potential to provide a better understanding of mechanisms that affect appetite and feeding behaviour in children.

Independent and synergistic effects of calcium and protein on appetite and energy intake in humans

There is convincing evidence that a high protein intake supresses appetite and reduces subsequent energy intake; associated with increases in satiety and the release of several gut peptides. Calcium intake may also elicit an improvement in appetite regulation and reduce subsequent energy intake, although the few studies that have assessed its direct impact are controversial. We aimed to assess whether calcium and protein exhibit a synergistic effect on appetite and energy intake as well as influencing these independently. Healthy male (n= 13) and female (n= 7) adults were recruited for the study. In a randomised double-blind, cross-over design each participant completed four trials. Each trial consisted of consuming a porridge based pre-load in a fasted state with differing calcium and protein content (porridge only, CON; high protein, PRO; high calcium, CAL; high protein and calcium, PROCAL). Visual analogue scales were used to determine subjective appetite sensations pre and at 15 min intervals during a 60 min post-prandial period, which was followed by the consumption of a pasta based test-meal ad-libitum. Time-averaged area under the curve subjective appetite ratings and mean food (g) and energy (kJ) intake of the ad-libitum test-meal in each trial were compared using ANOVA.