RESUMEN
Purpose: There is an increasing interest in the use of non-nutritive sweeteners to replace added sugar in food and beverage products for reasons of improving consumer health. Much work has been done to understand safety of sweeteners, but very little on sustainability. To address that gap, this study presents the results of a life cycle assessment (LCA) of production of rebaudioside A 60%, 95% pure (RA60) steviol glycoside mix from Stevia rebaudiana leaf grown in Europe. Methods: An attributional cradle-to-factory-gate life cycle assessment was conducted on growing of stevia leaves and extraction of steviol glycosides in Europe. Primary data were used from a case study supply chain. Results are reported in impact categories from the ReCiPe 2016 (H) method, with focus given to global warming potential, freshwater eutrophication, water consumption, and land use. Impacts are expressed both in terms of production mass and sweetness equivalence, a common metric for understanding high intensity sweetener potency. Sweetness equivalence of RA60 is typically 200 to 300 times that of sugar. Comparison of environmental impact is made to sugar (sucrose) produced from both cane and beets. The research is part of the EU project SWEET (sweeteners and sweetness enhancers: impact on health, obesity, safety, and sustainability). Results and discussion: Global warming potential for production of RA60 was found to be 20.25 kgCO2-eq/kgRA60 on a mass basis and 0.081 kgCO2-eq/kgSE on a sweetness equivalence basis. Field production of stevia leaves was found to be the main source of impact for most impact categories, and for all four focus categories. Extraction of the RA60 was the main source of impact for the others. Leaf processing and seedling propagation were minor contributors to life cycle impact. Removal of international transport from the supply chain reduced global warming potential by 18.8%. Compared with sugar on a sweetness equivalence basis, RA60 has approximately 5.7% to 10.2% the impact for global warming potential, 5.6% to 7.2% the impact for land use, and is lower across most other impact categories. Conclusion: This is the first LCA of steviol glycoside mix RA60 produced from leaf in Europe. The results indicate that RA60 can be used to reduce environmental impact of providing a sweet taste by replacing sugar across all impact categories. However, it is important to note that specific formulations in which RA60 is used will have a bearing on the final environmental impact of any food or beverage products. For solid foods, this requires further research. Supplementary Information: The online version contains supplementary material available at 10.1007/s11367-022-02127-9.
RESUMEN
Food systems are significant sources of global greenhouse gas emissions (GHGE). Since emission intensity varies greatly between different foods, changing food choices towards those with lower GHGE could make an important contribution to mitigating climate change. Public engagement events offer an opportunity to communicate these multifaceted issues and raise awareness about the climate change impact of food choices. An interdisciplinary team of researchers was preparing food and climate change educational activities for summer 2020. However, the COVID-19 pandemic and lockdown disrupted these plans. In this paper, we report on shifting these events online over the month of June 2020. We discuss what we did and the reception to our online programme. We then reflect on and highlight issues that arose. These relate to: (1) the power dynamics of children, diet and climate change; (2) mental health, diet and COVID-19; (3) engaging the wider science, agriculture and food communities; (4) the benefits of being unfunded and the homemade nature of this programme; (5) the food system, STEAM (science, technology, engineering, arts and mathematics) and diversity; and (6) how our work fits into our ongoing journey of food and climate change education.
RESUMEN
Nutritional experiences during infancy and toddlerhood influence the development of healthy eating habits later in life. Interest into solid food introduction practices has experienced resurgence due to the popularization of the baby-led weaning (BLW) approach as an alternative to more traditional parent-led weaning (PLW) practices. Although the literature shows beneficial effects of BLW on eating behaviours, the magnitude of those effects is unknown making parental expectation management challenging. This study provides an estimation of the size of the difference between the solid feeding practices groups for a variety of practices consistent with the development of healthy food preferences and behaviours. 565 participants with infants between 12 and 36 months old completed a survey concerning their preferred parental feeding styles, parental feeding practices, sources of information on feeding and toddler's eating behaviour. Participants were categorised to one of four groups reflecting the level of infant self-feeding level a month after the introduction of solid food (Strict PLW, Predominant PLW, Predominant BLW and Strict BLW). Estimated effect sizes of the observed significant differences showed that the magnitude of effects was modest to minimal. Moderate effect sizes were observed in comparisons regarding breastfeeding duration, maternal feeding practices, sources of information and types of first food given to the infants at the beginning of solid feeding introduction. When it comes to toddlers' eating behaviour and the family food environment, although some differences were statistically significant, the effect sizes were very small. Considering the long-lasting impact of food preferences developed at this stage along with the stress surrounding infant feeding decisions, it is crucial that the complementary feeding advice parents receive reflects realistic expectations of the outcomes regarding the effects on eating behaviour.
Asunto(s)
Conducta Alimentaria , Fenómenos Fisiológicos Nutricionales del Lactante , Responsabilidad Parental , Adulto , Preescolar , Dieta Saludable , Femenino , Humanos , Lactante , Conducta del Lactante , Masculino , Reino Unido , DesteteRESUMEN
We assessed evidence for changes in efficacy of food-based interventions aimed at reducing appetite or energy intake (EI), and whether this could be used to provide guidance on trial design. A systematic search identified randomized controlled trials testing sustained efficacy of diets, foods, supplements or food ingredients on appetite and/or EI. Trials had to include sufficient exposure duration (≥3 days) with appetite and/or EI measured after both acute and repeated exposures. Twenty-six trials met the inclusion criteria and reported data allowing for assessment of the acute and chronic effects of interventions. Most (21/26) measured appetite outcomes and over half (14/26) had objective measures of EI. A significant acute effect of the intervention was retained in 10 of 12 trials for appetite outcomes, and six of nine studies for EI. Initial effects were most likely retained where these were more robust and studies adequately powered. Where the initial, acute effect was not statistically significant, a significant effect was later observed in only two of nine studies for appetite and none of five studies for EI. Maintenance of intervention effects on appetite or EI needs to be confirmed but seems likely where acute effects are robust and replicable in adequately powered studies.
Asunto(s)
Apetito/fisiología , Dieta , Ingestión de Energía/fisiología , Respuesta de Saciedad/fisiología , HumanosRESUMEN
BACKGROUND: Overeating and obesity are frequently attributed to an addiction to food. However, there is currently a lack of evidence to support the idea that certain foods contain any specific addictive substance. An alternative approach is to focus on dimensions of observable behaviour, which may underpin a behavioural addiction to eating. To facilitate this, it is necessary to develop a tool to quantify addiction-like eating behaviour, which is not based on the clinical criteria for substance dependence. The current study provides initial validation of the Addiction-like Eating Behaviour Scale (AEBS). METHODS: English speaking male and female participants (N=511) from a community sample completed the AEBS, alongside a range of other health- and eating-related questionnaires including the Yale Food Addiction Scale (YFAS) and Binge Eating Scale (BES). Participants also provided their height and weight to enable calculation of body mass index (BMI). Finally, to assess test-retest reliability, an additional 70 participants completed the AEBS twice, 2 weeks apart. RESULTS: Principle components analysis revealed that a two-factor structure best accounted for the data. Factor 1 consisted of items that referred to appetitive drive, whereas factor two consisted of items that referred to dietary control practices. Both subscales demonstrated good internal reliability and test-retest reliability, and a confirmatory factor analysis confirmed the two-factor scale structure. AEBS scores correlated positively with body mass index (BMI) (P<0.001) and other self-report measures of overeating. Importantly, the AEBS significantly predicted variance in BMI above that accounted for by both the YFAS and BES (P=0.027). CONCLUSIONS: The AEBS provides a valid and reliable tool to quantify the behavioural features of a potential 'eating addiction'. In doing so, the AEBS overcomes many limitations associated with applying substance-dependence criteria to eating.
Asunto(s)
Conducta Adictiva/psicología , Conducta Alimentaria/psicología , Adicción a la Comida/diagnóstico , Psicometría/instrumentación , Adulto , Anciano , Índice de Masa Corporal , Femenino , Adicción a la Comida/psicología , Humanos , Masculino , Persona de Mediana Edad , Análisis de Componente Principal , Escalas de Valoración Psiquiátrica , Reproducibilidad de los Resultados , Encuestas y Cuestionarios , Adulto JovenRESUMEN
Overfeeding experiments, in which we impose short-term positive energy balance, help unravel the cellular, physiological and behavioural adaptations to nutrient excess. These studies mimic longer-term mismatched energy expenditure and intake. There is considerable inter-individual heterogeneity in the magnitude of weight gain when exposed to similar relative caloric excess reflecting variable activation of compensatory adaptive mechanisms. Significantly, given similar relative weight gain, individuals may be protected from/predisposed to metabolic complications (insulin resistance, dyslipidaemia, hypertension), non-alcoholic fatty liver disease and cardiovascular disease. Similar mechanistic considerations underpinning the heterogeneity of overfeeding responses are pertinent in understanding emerging metabolic phenotypes, for example, metabolically unhealthy normal weight and metabolically healthy obesity. Intrinsic and extrinsic factors modulate individuals' overfeeding response: intrinsic factors include gender/hormonal status, genetic/ethnic background, baseline metabolic health and cardiorespiratory fitness; extrinsic factors include macronutrient (fat vs carbohydrate) content, fat/carbohydrate composition and overfeeding pattern. Subcutaneous adipose tissue (SAT) analysis, coupled with metabolic assessment, with overfeeding have revealed how SAT remodels to accommodate excess nutrients. SAT remodelling occurs either by hyperplasia (increased adipocyte number) or by hypertrophy (increased adipocyte size). Biological responses of SAT also govern the extent of ectopic (visceral/liver) triglyceride deposition. Body composition analysis by DEXA/MRI (dual energy X-ray absorptiometry/magnetic resonance imaging) have determined the relative expansion of SAT (including abdominal/gluteofemoral SAT) vs ectopic fat with overfeeding. Such studies have contributed to the adipose expandability hypothesis whereby SAT has a finite capacity to expand (governed by intrinsic biological characteristics), and once capacity is exceeded ectopic triglyceride deposition occurs. The potential for SAT expandability confers protection from/predisposes to the adverse metabolic responses to overfeeding. The concept of a personal fat threshold suggests a large inter-individual variation in SAT capacity with ectopic depot expansion/metabolic decompensation once one's own threshold is exceeded. This review summarises insight gained from overfeeding studies regarding susceptibility to obesity and related complications with nutrient excess.
Asunto(s)
Diabetes Mellitus Tipo 2/etiología , Susceptibilidad a Enfermedades , Enfermedad del Hígado Graso no Alcohólico/etiología , Obesidad/etiología , Hipernutrición/complicaciones , Grasa Subcutánea/patología , Absorciometría de Fotón , Adiposidad , Composición Corporal , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/fisiopatología , Humanos , Resistencia a la Insulina/fisiología , Enfermedad del Hígado Graso no Alcohólico/metabolismo , Enfermedad del Hígado Graso no Alcohólico/fisiopatología , Obesidad/metabolismo , Obesidad/fisiopatología , Hipernutrición/metabolismo , Hipernutrición/fisiopatología , Grasa Subcutánea/diagnóstico por imagen , Triglicéridos/metabolismo , Aumento de Peso/fisiologíaRESUMEN
BACKGROUND: Acute and medium-term intervention studies suggest that non-nutritive sweeteners (NNS) are beneficial for weight loss, however there is limited human data on the long-term effects of consuming NNS on weight loss, maintenance, and appetite. Further research is therefore required to elucidate the prolonged impact of NNS consumption on these outcome measures. METHODS/DESIGN: A randomized parallel groups design will be used to assess whether regular NNS beverage intake is equivalent to a water control in promoting weight loss over 12-weeks (weekly weight loss sessions; Phase I), then supporting weight maintenance over 40-weeks (monthly sessions; Phase II) and subsequently independent weight maintenance over 52-weeks (Phase III) in 432 participants. A subset of these participants (n=116) will complete laboratory-based appetite probe days (15 sessions; 3 sessions each at baseline, at the start of phase I and the end of each phase). A separate subset (n=50) will complete body composition scans (DXA) at baseline and at the end of each phase. All participants will regularly be weighed and will complete questionnaires and cognitive tasks to assess changes in body weight and appetitive behaviours. Measures of physical activity and biochemical markers will also be taken. DISCUSSION: The trial will assess the efficacy of NNS beverages compared to water during a behavioural weight loss and maintenance programme. We aim to understand whether the impact of NNS on weight, dietary adherence and well-being are beneficial or transient and effects on prolonged successful weight loss and weight maintenance through sustained changes in appetite and eating behaviour. TRIAL REGISTRATION: Clinical Trials: NCT02591134; registered: 23.10.2015.
Asunto(s)
Bebidas , Agua Potable , Edulcorantes no Nutritivos/uso terapéutico , Obesidad/terapia , Programas de Reducción de Peso , Absorciometría de Fotón , Adulto , Anciano , Composición Corporal , Femenino , Humanos , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Adulto JovenRESUMEN
The effect of coconut oil (CO, containing mainly medium chain triglycerides - MCTs) and sunflower oil (SO, containing mainly long chain triglycerides - LCTs) used as fat source (10% fat ice cream) in different ratios (25% CO and 75% SO - 25CO:75SO, 50% CO and 50% SO - 50CO:50SO, 75% CO and 25% SO - 75CO:25SO) was investigated to assess differences in appetite and ad-libitum (evening and snack) food intake using a single blind design. 36 healthy female participants consumed a fixed portion (150g) of ice cream 45min before an ad-libitum dinner and snacks. Appetite sensations were tracked across the day. Participants ate significantly less fat after 75CO:25SO than 25CO:75SO (p=0.007) and there was also a trend for lower fat intake in this condition as compared to 50CO:50SO (p=0.068). High fat savoury snack intake significantly decreased after 75CO:25SO in comparison with both 25CO:75SO (p=0.038) and 50CO:50SO (p=0.008). Calorie intake from snacks was also found to be significantly lower after 25CO:75SO and 50CO:50SO than 75CO:25SO (p=0.021 and 0.030 respectively). There was no effect of condition on appetite or desire ratings over the day. Eating a standard portion of ice cream containing different ratios of MCTs and LCTs can modestly influence acute food selection and intake, with MCTs manifesting their effect earlier and LCTs later due to differences in the absorption and metabolism of these lipids. However, the differences evident in the present study were small, and require further research before firm conclusions can be drawn.
Asunto(s)
Apetito/fisiología , Conducta de Elección/fisiología , Ingestión de Alimentos/fisiología , Preferencias Alimentarias/psicología , Helados , Percepción del Gusto/fisiología , Adulto , Análisis de Varianza , Aceite de Coco , Femenino , Humanos , Aceites de Plantas , Aceite de Girasol , Gusto/fisiología , Escala Visual Analógica , Adulto JovenRESUMEN
BACKGROUND/OBJECTIVES: Obesity is common following hypothalamic damage due to tumours. Homeostatic and non-homeostatic brain centres control appetite and energy balance but their interaction in the presence of hypothalamic damage remains unknown. We hypothesized that abnormal appetite in obese patients with hypothalamic damage results from aberrant brain processing of food stimuli. We sought to establish differences in activation of brain food motivation and reward neurocircuitry in patients with hypothalamic obesity (HO) compared with patients with hypothalamic damage whose weight had remained stable. SUBJECTS/METHODS: In a cross-sectional study at a University Clinical Research Centre, we studied 9 patients with HO, 10 age-matched obese controls, 7 patients who remained weight-stable following hypothalamic insult (HWS) and 10 non-obese controls. Functional magnetic resonance imaging was performed in the fasted state, 1 h and 3 h after a test meal, while subjects were presented with images of high-calorie foods, low-calorie foods and non-food objects. Insulin, glucagon-like peptide-1, Peptide YY and ghrelin were measured throughout the experiment, and appetite ratings were recorded. RESULTS: Mean neural activation in the posterior insula and lingual gyrus (brain areas linked to food motivation and reward value of food) in HWS were significantly lower than in the other three groups (P=0.001). A significant negative correlation was found between insulin levels and posterior insula activation (P=0.002). CONCLUSIONS: Neural pathways associated with food motivation and reward-related behaviour, and the influence of insulin on their activation may be involved in the pathophysiology of HO.
Asunto(s)
Lesiones Encefálicas/fisiopatología , Alimentos , Neuroimagen Funcional , Hipotálamo/fisiopatología , Vías Nerviosas/fisiopatología , Obesidad/fisiopatología , Estimulación Luminosa , Lesiones Encefálicas/psicología , Mapeo Encefálico , Corteza Cerebral/fisiopatología , Señales (Psicología) , Femenino , Humanos , Hipotálamo/lesiones , Masculino , Persona de Mediana Edad , Obesidad/psicología , Recompensa , Reino UnidoRESUMEN
It has been suggested that providing consumers with smaller dishware may prove an effective way of helping people eat less and preventing weight gain, but experimental evidence supporting this has been mixed. The objective of the present work was to examine the current evidence base for whether experimentally manipulated differences in dishware size influence food consumption. We systematically reviewed studies that experimentally manipulated the dishware size participants served themselves at a meal with and measured subsequent food intake. We used inverse variance meta-analysis, calculating the standardized mean difference (SMD) in food intake between smaller and larger dishware size conditions. Nine experiments from eight publications were eligible for inclusion. The majority of experiments found no significance difference in food intake when participants ate from smaller vs. larger dishware. With all available data included, analysis indicated a marginal effect of dishware size on food intake, with larger dishware size associated with greater intake. However, this effect was small and there was a large amount of heterogeneity across studies (SMD: -0.18, 95% confidence interval: -0.35, 0.00, I(2) = 77%). Evidence to date does not show that dishware size has a consistent effect on food intake, so recommendations surrounding the use of smaller plates/dishware to improve public health may be premature.
Asunto(s)
Utensilios de Comida y Culinaria , Conducta Alimentaria , Obesidad/prevención & control , Tamaño de la Porción , Ingestión de Alimentos , Ingestión de Energía , Conducta Alimentaria/psicología , Humanos , Obesidad/psicología , Tamaño de la Porción/psicologíaRESUMEN
BACKGROUND/OBJECTIVE: The World Health Assembly recommends that children's exposure to marketing of unhealthy foods should be reduced. Nutrient profile models have been developed that define 'unhealthy' to support regulation of broadcast advertising of foods to children. The level of agreement between these models is not clear. The objective of this study was to measure the agreement between eight nutrient profile models that have been proposed for the regulation of marketing to children over (a) how many and (b) what kind of foods should be permitted to be advertised during television viewed by children. SUBJECTS/METHODS: A representative data set of commercials for foods broadcast during television viewed by children in the UK was collected in 2008. The data set consisted of 11,763 commercials for 336 different products or brands. This data set was supplemented with nutrition data from company web sites, food packaging and a food composition table, and the nutrient profile models were applied. RESULTS: The percentage of commercials that would be permitted by the different nutrient profile models ranged from 2.1% (0.4%, 3.7%) to 47.4% (42.1%, 52.6%). Half of the pairwise comparisons between models yielded kappa statistics less than 0.2, indicating that there was little agreement between models. CONCLUSIONS: Policy makers considering the regulation of broadcast advertising to children should carefully consider the choice of nutrient profile model to support the regulation, as this choice will have considerable influence on the outcome of the regulation.
Asunto(s)
Publicidad , Dieta , Industria de Alimentos , Modelos Teóricos , Política Nutricional , Televisión , Adolescente , Publicidad/estadística & datos numéricos , Niño , Preescolar , Alimentos , Industria de Alimentos/estadística & datos numéricos , Humanos , Reino UnidoRESUMEN
Foods and dietary patterns that enhance satiety may provide benefit to consumers. The aim of the present review was to describe, consider and evaluate research on potential benefits of enhanced satiety. The proposal that enhanced satiety could only benefit consumers by a direct effect on food intake should be rejected. Instead, it is proposed that there is a variety of routes through which enhanced satiety could (indirectly) benefit dietary control or weight-management goals. The review highlights specific potential benefits of satiety, including: providing appetite control strategies for consumers generally and for those who are highly responsive to food cues; offering pleasure and satisfaction associated with low-energy/healthier versions of foods without feeling 'deprived'; reducing dysphoric mood associated with hunger especially during energy restriction; and improved compliance with healthy eating or weight-management efforts. There is convincing evidence of short-term satiety benefits, but only probable evidence for longer-term benefits to hunger management, possible evidence of benefits to mood and cognition, inadequate evidence that satiety enhancement can promote weight loss, and no evidence on which consumers would benefit most from satiety enhancement. The appetite-reducing effects of specific foods or diets will be much more subtle than those of pharmaceutical compounds in managing hunger; nevertheless, the experience of pharmacology in producing weight loss via effects on appetite suggests that there is potential benefit of satiety enhancement from foods incorporated into the diet to the consumer.
Asunto(s)
Dieta , Alimentos , Saciedad/fisiología , Afecto , Regulación del Apetito , Cognición/fisiología , Ingestión de Alimentos/fisiología , Ingestión de Alimentos/psicología , Ingestión de Energía , Promoción de la Salud , Humanos , Hambre , Placer , Pérdida de PesoRESUMEN
The impact of two commercially available products, a patented herb extract Yerbe Maté, Guarana and Damiana (YGD) formulation and an inulin-based soluble fermentable fibre (SFF), alone or in combination, on appetite and food intake were studied for the first time in a double blind, placebo-controlled, cross-over design. 58 normal to slightly overweight women consumed a fixed-load breakfast followed 4h later by an ad libitum lunch. They were administered YGD (3 tablets) and SFF (5g in 100ml water), YGD and water (100ml), SFF and placebo (3 tablets) or water and placebo 15min before meals. Appetite was assessed using visual analogue scales, and energy intake was measured at lunch. Significant reductions in food intake and energy intake were observed when YGD was present (59.5g, 16.3%; 112.4kcal, 17.3%) and when SFF was present (31.9g, 9.1%; 80kcal, 11.7%) compared with conditions were products were absent. The lowest intake (gram and kcal) was in the YGD+SFF condition. Significant reductions in AUC hunger and AUC desire to eat were also observed after YGD+SFF combination. The data demonstrate that YGD produces a robust short-term effect on caloric intake, an effect augmented by SFF. Caloric compensation for SFF indicates independent effects on appetite regulation.
Asunto(s)
Apetito/efectos de los fármacos , Fibras de la Dieta/farmacología , Ingestión de Energía/efectos de los fármacos , Preferencias Alimentarias/efectos de los fármacos , Inulina/farmacología , Obesidad/prevención & control , Extractos Vegetales/farmacología , Adolescente , Adulto , Anciano , Apetito/fisiología , Área Bajo la Curva , Estudios Cruzados , Dieta , Fibras de la Dieta/uso terapéutico , Método Doble Ciego , Femenino , Humanos , Ilex paraguariensis , Inulina/uso terapéutico , Comidas , Persona de Mediana Edad , Obesidad/fisiopatología , Sobrepeso , Paullinia , Fitoterapia , Extractos Vegetales/uso terapéutico , Método Simple Ciego , Turnera , Adulto JovenRESUMEN
Narcolepsy-cataplexy is characterised by orexin deficiency, sleep disturbance, obesity and dysautonomia. Ghrelin and obestatin affect both energy intake and sleep. Our aim was to investigate ghrelin, obestatin and metabolic/autonomic function in narcolepsy-cataplexy. Eight narcolepsy-cataplexy patients (seven CSF orexin-deficient) and eight matched controls were studied. The subjects had a fixed energy meal with serial blood samples and measurement of heart rate variability (HRV). Fasting plasma obestatin was more than threefold higher in narcolepsy subjects (narcolepsy 89.6 ± 16 pg/ml vs. control 24.9 ± 3 pg/ml, p < 0.001). There was no change in HRV total power, but post-prandial low-frequency (LF) power and high-frequency (HF) power were lower in the narcolepsy group [area under the curve (AUC): HF power narcolepsy 1.4 × 10(5) ± 0.2 × 10(5) vs. control 3.3 × 10(5) ± 0.6 × 10(5 )ms(2)/h, p < 0.001]. On multiple regression analyses, the only significant predictor of plasma obestatin was HF power, which was inversely correlated with obestatin (ß = -0.65 R (2) = 38 %, p = 0.009). Fasting and post-prandial plasma ghrelin were similar in both groups (narcolepsy 589.5 ± 88 pg/ml vs. control 686.9 ± 81 pg/ml, p = 0.5; post-prandial AUC-narcolepsy 161.3 ± 22 ng/ml/min vs. control 188.6 ± 62 ng/ml/min, p = 0.4). Only the narcolepsy group had significant suppression of plasma ghrelin after the meal (ANOVA, p = 0.004). In orexin-deficient narcolepsy, fasting plasma ghrelin is unaltered, and post-prandial suppression is preserved. Fasting plasma obestatin is increased and correlates with autonomic dysfunction. As obestatin affects NREM sleep, we suggest that increased plasma levels contribute to the disrupted sleep-state control in narcolepsy.
Asunto(s)
Sistema Nervioso Autónomo/fisiopatología , Ghrelina/sangre , Péptidos y Proteínas de Señalización Intracelular/deficiencia , Narcolepsia/sangre , Neuropéptidos/deficiencia , Adulto , Ayuno/sangre , Femenino , Humanos , Péptidos y Proteínas de Señalización Intracelular/sangre , Masculino , Persona de Mediana Edad , Narcolepsia/fisiopatología , Neuropéptidos/sangre , Orexinas , Periodo PosprandialRESUMEN
OBJECTIVE: Short-term fasting is associated with increased GH pulsatility and mobilisation of fats, but underlying mechanisms are unclear. We studied ghrelin's role during fasting and the effects of exogenous ghrelin on lipid mobilisation. DESIGN: Randomised placebo-controlled study. METHODS: In this study, ten controls (body mass index (BMI) 23.3±3.2), ten morbidly obese subjects (BMI 50.1±10.6) and six post-gastrectomy subjects (BMI 25.2±1.0) were fasted for 36â h undergoing regular blood sampling. On a separate occasion, subjects were infused with either i.v. ghrelin (5 âpmol/kg per min) or saline over 270â min. RESULTS: Obese and post-gastrectomy subjects had lower ghrelin compared with controls (ANOVA, P=0.02) during the fast. Controls and gastrectomy subjects showed a similar increase in GH pulsatility, circulating non-esterified fatty acids (NEFA) and 3ß-hydroxybutyrate (3 HB). Obese subjects had an impaired GH response (P<0.001), reduced excursions of 3 HB (P=0.01) but no change in NEFA excursions (P=0.09) compared with controls. Ghrelin infusion increased GH, NEFA and ketone bodies (ANOVA, P<0.0001) in all the three groups, but GH response was impaired in the obese subjects (P=0.001). Ghrelin also induced a significant (ANOVA, P=0.004) biphasic NEFA response to meals in all the subjects. CONCLUSIONS: Despite low circulating ghrelin, gastrectomy subjects maintain a normal metabolic response to fasting, implying that ghrelin plays a minimal role. In contrast, infused ghrelin has significant effects on lipid mobilisation and induces a marked biphasic NEFA response to meals. Hence, ghrelin may play a significant role in meal-related substrate utilisation and metabolic flexibility.
Asunto(s)
Ayuno/fisiología , Gastrectomía , Ghrelina/fisiología , Movilización Lipídica/efectos de los fármacos , Obesidad Mórbida/fisiopatología , Adulto , Anciano , Glucemia/metabolismo , Ácidos Grasos no Esterificados/sangre , Femenino , Ghrelina/farmacología , Humanos , Insulina/sangre , Cuerpos Cetónicos/sangre , Masculino , Persona de Mediana EdadRESUMEN
OBJECTIVE: Ghrelin inhibits sympathetic nervous system (SNS) activity in rodents. We studied the effect of ghrelin on healthy humans, in obesity and in vagotomized subjects. DESIGN: Randomized, double-blinded, placebo-controlled crossover. SUBJECTS: Seven lean [mean body mass index (BMI) 23·6 ± 0·9 kg/m(2) ], seven morbidly obese (mean BMI 50·9 ± 4·4 kg/m(2) ) and seven post-gastrectomy subjects (mean BMI 22·0 ± 1·1 kg/m(2) ). MEASUREMENTS: Subjects were randomized to intravenous ghrelin (5 pmol/kg/min) or saline over 270 min. Subjects had a fixed calorie meal and a free choice buffet during the infusion. Heart rate variability (HRV) was measured. Total power (TP) represents overall autonomic function, low-frequency (LF) power represents sympathetic and parasympathetic activity, and high-frequency (HF) power represents parasympathetic activity. Very low (VLO) frequency represents the frequency band associated with thermogenesis. RESULTS: Preliminary anova analysis, looking at all three subject groups together, showed that ghrelin had an overall highly significant inhibitory effect on TP (P = 0·001), HF power (P = 0·04), VLO power (P = 0·03) and no effect on LF (P = 0·07). Further subset analysis revealed that ghrelin had a significant effect on TP (P = 0·03), borderline effect on LF power (P = 0·06) and no effect on HF power (P = 0·1) in healthy controls. By contrast in obese subjects, ghrelin had no effect on TP (P = 0·3), LF (P = 0·5) and HF (P = 0·06) and also no effect in the vagotomized subjects on TP (P = 0·7), LF (P = 0·7) and HF (P = 0·9). Ghrelin had no effect on the LF/HF ratio. CONCLUSIONS: Ghrelin inhibits SNS activity in healthy controls with a moderate effect on parasympathetic nervous system activity but had no effect on obese subjects. Vagotomized subjects also did not respond to ghrelin, suggesting the vagus nerve is important for the effects of peripheral ghrelin on the SNS.
Asunto(s)
Sistema Nervioso Autónomo/fisiología , Ghrelina/farmacología , Obesidad Mórbida/fisiopatología , Nervio Vago/fisiología , Adulto , Anciano , Sistema Nervioso Autónomo/efectos de los fármacos , Glucemia/metabolismo , Presión Sanguínea/efectos de los fármacos , Estudios Cruzados , Femenino , Gastrectomía , Frecuencia Cardíaca/efectos de los fármacos , Humanos , Insulina/sangre , Masculino , Persona de Mediana Edad , Sistema Nervioso Parasimpático/efectos de los fármacos , Sistema Nervioso Parasimpático/fisiopatología , Neoplasias Gástricas/cirugía , Sistema Nervioso Simpático/efectos de los fármacos , Sistema Nervioso Simpático/fisiopatología , Termogénesis/efectos de los fármacos , VagotomíaRESUMEN
Fifty-five women were recruited and assigned to a control group or an oral contraceptive (OC) use group. For the control groups menstrual cycle phase was determined using a menstrual calendar and only participants with regular cycles were recruited. Testing was carried out during a single day of the luteal and follicular phases, where participants were asked to consume and rate sweet and savoury snacks. Participants in the OC group were tested on the equivalent days of their pill calendar. In both groups, the luteal phase induced a greater caloric intake of sweet foods without altering hedonic ratings. No significant interactions between either phase or flavour with OC use on food intake or hedonic food ratings were found. At least for snack items, OC do not seem to alter the caloric intake fluctuations that occur during a normal menstrual cycle.