The hypothesis that fluid dairy consumption before and with a meal decreases short-term appetite and food intake (FI) and improves glycemic control compared with a sugar-sweetened beverage in normal weight (NW) and overweight/obese (OW/OB) children was explored. Isocaloric (130 kcal) beverages of 2% milk, 1% chocolate milk, 1.5% yogurt drink, fruit punch and water were compared. In Experiment 1, FI was lower after chocolate milk and yogurt drink than water. In Experiment 2, milk led to lower pre-meal glucose and higher pre-meal GLP-1 than fruit punch in all children. When intake was adjusted for body weight (kcal/kg), post-meal glucose, insulin and GLP-1increased, and ghrelin decreased more in OW/OB than NW children. Post-meal PYY was higher after milk in all children. Therefore, fluid dairy does not reduce FI and appetite more than other caloric beverages, but milk results in lower pre-meal glucose and more favourable responses in satiety hormones in children.

M.Sc.

High multivitamin (10-fold, HV) and high folic acid diets fed to pregnant Wistar rats increase obesity and components of the metabolic syndrome in the offspring, but the effects on the post-weaning maternal phenotype are unclear. The hypothesis that methyl group vitamins are determinants of the HV diet-induced phenotype in the mother when fed a high fat diet post-weaning through alterations in homeostatic, hedonic and peripheral regulatory systems was tested. Wistar rats were fed AIN-93G diets containing either 1) recommended multivitamins (RV, control), 2) HV 3) HV with recommended folic acid (HVRF; 1-fold folic acid), or 4) RV with high methyl group vitamins (HMethyl; 10-fold folic acid, vitamin B12 and B6) during pregnancy alone. All groups were fed a RV diet during lactation until weaning and a RV high fat (60% fat) diet for 16 weeks post-weaning. Dams fed the HV, HVRF and HMethyl diet gained more weight from 2 to 15 weeks post-weaning and their weight gain was dependent on post-weaning food intake. In contrast, only HV dams demonstrated hypo-functioning of mesolimbic reward pathway and higher expression of several genes in the hypothalamus and peripheral tissues involved in the regulation of energy balance. In conclusion, HV, HVRF and HMethyl diets fed during pregnancy predispose the mother to weight gain when exposed to a high fat diet post-weaning, however the diets were not consistent in their effects on central and peripheral regulatory systems leaving uncertain the primary mechanism(s) of action of vitamin-induced weight gain.

M.Sc.

2016-05-11 00:00:00

High dietary sodium intake is hypothesized to increase food intake (FI), fluid intake and glycemic response. Two short-term randomized repeated-measures studies measured the effects of acute sodium intake on FI, water intake (WI), subjective appetite (SA), thirst, and blood glucose (BG) in young men. Sodium additions were 740 and 1480 mg to a solid food (beans) in Experiment 1; and 500, 1000, 1500 and 2000 mg to a beverage (tomato juice) in Experiment 2. FI and WI were measured at ad libitum pizza meals 120 and 30 min later, respectively. SA, thirst and BG were measured at intervals before and after pizza. Compared with controls, treatments with added-sodium had no effect on dependent measures. In conclusion, acute intake of sodium in a solid or liquid matrix does not increase subjective ratings of appetite or thirst, ad libitum food or water intakes, or blood glucose in healthy young adults.

MAST

In order to elucidate the component(s) of yellow peas responsible for their health benefits, the effects of 10 or 20 g of isolated yellow pea protein (P10 and P20) or fibre (F10 and F20) on food intake (FI) at an ad libitum pizza meal served at 30 min (experiment 1) or 120 min (experiment 2), blood glucose (BG) and appetite in young healthy males (20-30 y) were investigated. In experiment 1, P20 suppressed FI compared to all other treatments and lowered cumulative FI (pizza meal kcal + treatment kcal) compared to F10. Protein treatments suppressed pre-meal (0-30 min) BG compared to control, whereas only P20 suppressed post-meal (50-120 min) BG. In experiment 2, there was no effect of treatment on any outcome measures. Thus, protein is the component responsible for the short-term effects of yellow peas on glycaemia and FI, but its second-meal effects diminish by 2 hours post-consumption.

MAST

The hypothesis that high multivitamin gestational (HV) diets affect the development of central serotonergic regulatory systems in female offspring, and that this is due to its high folic acid content, was investigated. Dams were fed the AIN-93G diet containing the recommended multivitamin mix (RV), 10-fold the RV amount (HV), or the RV diet with 10-fold the folic acid (Hfol). Serotonergic control of food intake and macronutrient selection was assessed by measuring long-term intake and selection, short-term intake and selection following injections of serotonin receptor agonists, and hypothalamic serotonin receptor expression. Offspring from Hfol dams selected more protein and were less responsive to agonist injections, but showed no altered serotonin receptor expression. In contrast, those born to HV fed dams were not different from the RV controls in any measure. In conclusion, the Hfol, but not HV gestational diet affects serotonergic regulation of food intake in female rat offspring.

MAST

The effect of meal-time exposure to food advertisements (FA) on food intake, subjective appetite and caloric compensation was investigated in overweight/obese (OW/OB) and normal weight (NW) boys (study 1) and girls (study 2). In random order, each participant watched either FA or non-food advertisements (NFA) 30 min after consumption of either a non-caloric sweetened control (CON) or a glucose (GLU) drink. Food advertisements increased food intake only in OW/OB girls. The GLU drink reduced food intake in both girls and boys despite no changes in subjective appetite. Food advertisements did not modify the response to the GLU drink in girls and contrary to the hypothesis they magnified the reduction in energy intake following the GLU drink in boys. In conclusion, FA in a TV program during consumption of a pizza meal by NW and OW/OB boys and girls increased food intake only in OW/OB girls and increased caloric compensation for the GLU drink at meal time in boys but not in girls.

MAST

In order to examine the effects of industry processed pulse powder (navy bean, lentil and chickpea) on postprandial glycaemic response (BG) and subjective appetite (App) before and after a subsequent meal, three randomized, within-subject experiments on healthy young men were conducted. In experiment 1, all navy bean treatments reduced BG at 30 min and navy bean powder suppressed pre-meal App compared to whole wheat flour. In experiment 2, all lentil treatments reduced pre-meal BG compared to whole wheat flour. However, no App differences were observed. In experiment 3, all chickpea treatments reduced pre-meal BG compared to whole wheat flour. However, no App differences were observed. Therefore, navy bean powder, lentil powder and chickpea powder maintain their low GI and satiating effects, regardless of processing. Pulse powder can be used as a value-added food ingredient to moderate glycaemic response and increase satiety.

MAST

The effect of exercise (EXR) on food intake (FI), subjective appetite and net energy balance was investigated in normal weight (NW), overweight (OW) and obese (OB) boys. Each boy received in random order either a non-caloric sweetened control (CON) or glucose (GLU) drink after either EXR or sedentary activity. Normal weight and OW/OB boys exercised at their ventilation threshold (VeT) in experiment 1 and NW boys exercised at 25% above their VeT in experiment 2. Overweight/OB boys ate significantly more total food than NW boys but not when adjusted for body weight. Food intake was lower after the GLU drink. Although EXR increased average appetite it did not affect FI. However, net energy balance was reduced by EXR in OW/OB boys, but not in NW boys. Thus, while EXR increases subjective appetite, apparent intake compensation occurred only in NW, but not in OW/OB boys, resulting in reduced net energy balance in OW/OB boys.

MAST

High folic acid consumed during pregnancy promotes characteristics of metabolic syndrome in rat offspring. We hypothesized that folic acid alters the development of hypothalamic food intake pathways in utero, contributing to the metabolic phenotype of the offspring in later life. Pregnant Wistar dams were fed modified AIN-93G diets containing folic acid at: 0, 1.0 (control), 2.5, 5.0, or 10.0-fold of the recommended level. The folic acid content in the gestational diet was reflected in the expression of neuropeptide Y (NPY) neurons and body weight of the male offspring at birth. Low and high gestational folic acid led to higher food intake and weight gain in the offspring to 9 weeks post-weaning, consistent with decreased activity of pro-opiomelanocortin (POMC) neurons. The folic acid content in the gestational diet affects in utero development of hypothalamic feeding circuits and contributes to a phenotype that reflects characteristics of the metabolic syndrome in the offspring.

M.Sc.

The hypothesis that consumption of whey protein (WP) prior to a meal suppresses short-term food intake and reduces post-meal glycemia by insulin-dependent and -independent mechanisms in healthy young adults was explored in three studies. Study one investigated the effect of solid vs. liquid forms of WP (50 g) and sucrose (75 g) on food intake at 1 h. Whey protein, whether in solid or liquid form, suppressed food intake more than sucrose. Study two examined the effect of WP (10-40 g) consumed 30 min prior to a meal on food intake, and pre- and post-meal blood concentrations of glucose and insulin. Whey protein reduced food intake and post-meal glycemia in a dose-dependent manner without increased blood insulin concentrations. In the third study, glycemic control after WP was compared with glucose, at doses of 10 and 20 g. Both pre-meal WP and glucose consumption reduced post-meal glycemia similarly. However, WP resulted in lower pre-meal blood glucose and delayed gastric emptying, lower pre-and post-meal and overall insulin secretion and concentrations and higher GLP-1 and PYY concentrations compared with glucose. Thus, the results of this research support the hypothesis that consumption of WP prior to a meal suppresses short-term food intake and reduces post-meal glycemia by insulin-dependent and -independent mechanisms in healthy young adults.

PhD

The hypothesis that milk consumption decreases short-term appetite and food intake and improves glycemic control compared with other caloric beverages in healthy young adults was explored in four experiments. The first two experiments compared isovolumetric amounts (500 ml) of milk (2% M.F.), chocolate milk (1% M.F.), a soy beverage, infant formula, orange juice and water on satiety and food intake and blood glucose before and after a meal provided at 30 min (Experiment 1) and 120 min (Experiment 2). Pre-meal ingestion of chocolate milk and infant formula (highest in calories) reduced food intake at 30 min, but not 2 h. Only milk reduced post-meal blood glucose in both experiments suggesting that its macronutrient composition is a factor in blood glucose control. Experiment 3 compared the effects of ad libitum consumption of milk (1% M.F.), regular cola, diet cola, orange juice and water at a pizza meal on fluid and ad libitum food intake and post-meal appetite and glycemia. Fluid volume consumed was similar, but all caloric beverages added to total meal-time energy intake. However, milk lowered post-meal blood glucose and appetite score. In Experiment 4, the effect of isovolumetric (500 ml) beverages of whole milk (3.25% M.F.) and each of its macronutrient components, protein (16 g), lactose (24 g), and fat (16 g) on glycemic control and gastrointestinal hormonal responses were examined. The reduction in post-prandial glycemia was mediated by interactions between its macronutrient components and associated with hormonal responses that slow stomach emptying and increase glucose disposal. Thus, the results of this research do not support the hypothesis that milk consumption decreases short-term appetite and food intake compared with other beverages; however, milk improves glycemic control by insulin-dependent and independent mechanisms.

PhD

High multivitamin (10-fold AIN-93G levels, HV) intake by Wistar rats during pregnancy results in increased male offspring's body weight and food intake and characteristics of the metabolic syndrome. The hypothesis of this research is that fat soluble vitamins, primarily due to vitamin A, are partially responsible for this effect through modification of development of brain pathways regulating food intake and reward in utero and post-weaning. Three studies were conducted. In study 1, dams were fed AIN-93G diets containing the recommended vitamins (RV) or RV with 10-fold fat soluble vitamins (HFS). In study 2, the dams were fed RV, RV with 10-fold vitamin A (HA) or HV diet with only the recommended vitamin A diets. Male offspring were weaned to a high fat diet for 14 weeks. In study 3, dams were fed the HV diet, while their male offspring were weaned to RV, HV or HA diets for 29 weeks. Study 1 showed that the HFS diet does not reproduce the effects of the HV gestational diet on body weight or food intake of the offspring, but affected development of their higher hedonic regulatory pathways associated with food preference. In study 2, HA intake alone in gestational diets had long-lasting programming effects on the dopaminergic system and decreased sucrose preference but not food intake in the offspring. In study 3, HA in the post-weaning diet reduced the effect of the HV dam's diet on the offspring and modified gene expression in food intake and reward pathways. In conclusion, fat soluble vitamins, explain little of the effect of the HV diet consumed during gestation on the male offspring phenotype, but primarily, due to vitamin A, are important modulators of brain pathways regulating reward both in utero and post-weaning.

2016-09-30 00:00:00

The relationship between substrate oxidation (RER) and food intake (FI) is undefined. This study examined the effects of RER modified by a glucose pre-load (GL), exercise (EX) and GL with EX on, FI and energy balance (NEB) in normal-weight boys (9-12 y) and men (20-30 y). Subjects (15 boys, 15 men) were randomized with treatments of either water or GL followed by either EX or rest. Measures included RER, energy expenditure (EE)(kcal/kg), subjective appetite, FI(kcal/kg) measured at a pizza lunch and NEB (kcal/kg). FI(kcal/kg) was reduced by GL(p < 0.0001), and further decreased with GL ingested prior to EX(p = 0.0254). RER was increased with GL(p < 0.0001) and EX(p = 0.0043), and was higher in men compared to boys (p = 0.007). There was no association between RER and FI(kcal/kg). In conclusion, there was no relationship between RER and FI, suggesting that FI is not affected by substrate oxidation.

MAST

The hypothesis that source of protein in a nutritionally adequate diet during gestation, lactation and weaning alters food intake and characteristics of metabolic syndrome in the offspring was investigated. Pregnant Wistar rats were randomized to either the AIN 93-G casein (C) or soy protein (S) diets (n=12/group) during gestation only or during gestation and lactation. Male offspring in each dams’ diet group were weaned to either C or S diets (n=12/group). Food intake, body weight (BW), fat pad mass, systolic (SBP) and diastolic (DBP) blood pressure, and plasma homocysteine (p<0.05) were higher in offspring born to dams fed the S diet. Fasting blood glucose (BG), BG in response to a glucose gavage and Homeostatic Model of Assessment of Insulin Resistance (HOMA-IR) index were higher only in male offspring born to dams fed the S diet. Moreover, gene expression of Agouti Related Protein (AgRP) was higher in offspring born to dams fed the S diet at weaning. Extending the dams’ diet during gestation and lactation magnified the effect of the gestational S diet on BW and composition and glucose metabolism in male offspring. Although composition of the weaning diets interacted with that of the dams’ diets, the latter was the dominant factor in determining metabolic outcomes in the offspring. In conclusion, the soy protein diet, compared to the casein diet when consumed during gestation or throughout gestation and lactation increased food intake and the presence of characteristics of metabolic syndrome in the offspring.

PhD

mins are readily available in the modern diet due to liberalized fortification and supplementation policies. This research tested the hypothesis that high multi-vitamin intake by Wistar rats during pregnancy leads to the development of obesity and characteristics of the metabolic syndrome in the offspring. Pregnant Wistar rats were fed the AIN-93G diet containing either the recommended (RV) or 10-fold increase (HV) in vitamin content. Pups were weaned to the RV diet (Study 1), an obesogenic liquid diet (Ob, Study 2), low vitamin diets (1/3RV or 1/6RV, Study 3), or a nutrient selection paradigm (NSP) with 10% and 60% casein diets (Study 4). Body weight (BW), food intake (FI), glucose and insulin responses, appetite hormones, abdominal fat pad mass (FPM) and systolic blood pressure (SBP) was measured. Expressions of mRNA for hypothalamic serotonin (5-HT) receptors and proopiomelanocortin (POMC) were measured in Study 4. Males, but not females, born to HV dams had higher post-weaning BW and FI when weaned to the RV or 1/3RV diet, and exhibited components of metabolic syndrome, including higher FPM, hyperglycemia, insulin resistance and elevated SBP compared with those born to RV dams. The Ob diet led to exaggerated weight gain and expressions of components of metabolic syndrome in both sexes born to dams fed the HV diet. Female pups on the 1/6RV diet from HV dams had two-fold higher glucose response and lower insulin response, but no difference in post-weaning BW and daily FI compared to those from RV dams. In contrast to the pups born to HV dams and fed a single diet, those from the HV dams and on the NSP gained less weight and ate less, and had lower hypothalamic mRNA expressions of 5-HT receptors and POMC. In conclusion, high multi-vitamin intake during pregnancy may lead to obesity, and result in a higher risk of developing characteristics of metabolic syndrome in the offspring. However, sex, weaning diet composition, and the presence of diet choice alter the outcomes.

PhD

Three studies were designed to investigate the hypothesis that physiological and environmental variables are both independent and interactive in determining food intake (FI) in children and adolescents during puberty (8 – 18 y old). Study 1 investigated the effect of obesity, sex and pubertal status on appetite hormones in response to a mixed glucose and whey protein (WP) drink in adolescents. Obese adolescents had higher insulin, PYY and lower ghrelin than normal weight (NW) controls, with a more pronounced effect in males. Puberty did not affect insulin, but the change in PYY in response to the drink was greater and ghrelin was lower in mid-late pubertal than pre-early pubertal obese males. To further describe the role of puberty, Study 2 examined the effect of pubertal status on FI following consumption of glucose and WP drinks in male and female children. In mid-late pubertal children, mealtime compensation for energy from glucose was less at 60 than at 30 min, but not for whey. However, compensation for either drink was not different at 30 and 60 min meals in pre-early pubertal children. Finally to demonstrate the interaction between puberty and environmental influences on FI, Study 3 examined the effect of distraction (television viewing, TVV) while eating and pubertal status on food intake after a pre-meal glucose drink in girls. In Study 3, TVV had no effect on FI, however, glucose suppressed FI more with no TVV compared with TVV (24% vs. 10%). In postpubertal girls, glucose reduced FI by ~27% in both the no TVV and TVV conditions, but in peripubertal girls, reduction in FI was 22% without TVV and only 1% while TVV. Thus, the results of this research support the hypothesis that physiological and environmental variables are both independent and interactive in determining FI in children and adolescents during puberty.

PhD

High vitamin (HV), AIN-93G diet with ten-fold the regular amount of vitamins (RV), consumed by pregnant Wistar rats increases characteristics of metabolic syndrome (MetS) in their first litters. Therefore, the effects of the maternal HV-diet on tissue mechanisms regulating insulin resistance in offspring (Part 1) and on characteristics of MetS in the dams and their second litter (L2) offspring (Part 2) were examined. Part 1 (studies 1 and 2) hypothesis was that the maternal HV-diet alters tissue fatty acid (FA) concentrations, expression of peroxisome-proliferator-activated receptors (PPARs) genes, and their regulation of metabolism in the offspring, favoring insulin resistance. Part 2 (studies 3 and 4) hypothesis was that high-vitamin intakes during the first pregnancy increase weight gain, food intake and markers of MetS in both the dams and their litters. In all experiments, dams were fed the RV or HV-diet. In study 4, a high-folic-acid-diet (HFol, RV+10-fold folic acid) was added. In studies 1 and 2, the offspring were weaned to an obesogenic diet. The HV-diet affected tissue FA concentrations (study 1), increased muscle PPAR-ɑ mRNA levels and uncoupled relationships between hepatic PPAR-γ mRNA levels and insulin resistance (study 2) in male offspring. In study 3, dams fed the HV-diet during the first pregnancy were maintained on the RV-diet and then mated again after 12wk. Their litters were fed the RV-diet. The HV-diet increased weight gain and food intake of both dams and L2, and insulin resistance in their offspring. In study 4, both HV and HFol-diets increased post-weaning weight gain, but differed in their effects on biomarkers of food intake regulation. In conclusion, feeding the HV-diet during the first pregnancy increases post-weaning body weight and food intake in Wistar rat dams, uncouples tissue regulation of glucose metabolism and promotes characteristics of MetS in their litters. Folic acid is not the only vitamin involved.

PhD