Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 5.241
Filtrar
2.
Vet Clin North Am Equine Pract ; 37(1): 139-175, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33820605

RESUMO

Skeletal muscle comprises 40% to 55% of mature body weight in horses, and its mass is determined largely by rates of muscle protein synthesis. In order to support exercise, appropriate energy sources are essential: glucose can support both anaerobic and aerobic exercise, whereas fat can only be metabolized aerobically. Following exercise, ingestion of nonfiber carbohydrates and protein can aid muscle growth and recovery. Muscle glycogen replenishment is slow in horses, regardless of dietary interventions. Several heritable muscle disorders, including type 1 and 2 polysaccharide storage myopathy and recurrent exertional rhabdomyolysis, can be managed in part by restricting dietary nonstructural carbohydrate intake.


Assuntos
Carboidratos da Dieta/metabolismo , Doenças dos Cavalos/etiologia , Músculo Esquelético/metabolismo , Doenças Musculares/veterinária , Estado Nutricional , Animais , Doenças dos Cavalos/patologia , Cavalos , Doenças Musculares/patologia
3.
Top Spinal Cord Inj Rehabil ; 27(1): 36-56, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33814882

RESUMO

The population with SCI is at a significant risk for both insulin resistance and type 2 diabetes mellitus (T2DM) secondary to neurogenic obesity. The prevalence of insulin resistance and T2DM in persons with SCI suggests that disorders of carbohydrate metabolism are at epidemic proportions within the population. However, the true frequency of such disorders may be underestimated because biomarkers of insulin resistance and T2DM used from the population without SCI remain nonspecific and may in fact fail to identify true cases that would benefit from intervention. Furthermore, diet and exercise have been used to help mitigate neurogenic obesity, but results on disorders of carbohydrate metabolism remain inconsistent, likely because of the various ways carbohydrate metabolism is assessed. The objective of this article is to review current literature on the prevalence and likely mechanisms driving insulin resistance and T2DM in persons with SCI. This article also explores the various assessments and diagnostic criteria used for insulin resistance and T2DM and briefly discusses the effects of exercise and/or diet to mitigate disorders of carbohydrate metabolism brought on by neurogenic obesity.


Assuntos
Diabetes Mellitus Tipo 2/etiologia , Resistência à Insulina , Obesidade/complicações , Traumatismos da Medula Espinal/complicações , Diabetes Mellitus Tipo 2/terapia , Carboidratos da Dieta/metabolismo , Terapia por Exercício , Humanos , Obesidade/terapia , Traumatismos da Medula Espinal/terapia
4.
Nutrients ; 13(4)2021 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-33916669

RESUMO

BACKGROUND: Diets have been a central component of lifestyle modification for decades. The Low-Carbohydrate Diet (LCD), originally conceived as a treatment strategy for intractable epilepsy (due to its association with ketogenesis), became popular in the 1970s and since then has risen to prominence as a weight loss strategy. OBJECTIVE: To explore the efficacy, limitations and potential safety concerns of the LCD. DATA SOURCES: We performed a narrative review, based on relevant articles written in English from a Pubmed search, using the terms 'low carbohydrate diet and metabolic health'. RESULTS: Evidence supports the efficacy of the LCD in the short-term (up to 6-months) for reduction in fat mass and remission of Type 2 Diabetes Mellitus (T2D). However, the longer-term efficacy of the LCD is disappointing, with diminishment of weight loss potential and metabolic benefits of the LCD beyond 6-months of its adoption. Furthermore, practical limitations of the LCD include the associated restriction of food choices that restrict the acceptability of the LCD for the individual, particularly over the longer term. There are also safety concerns of the LCD that stem from nutritional imbalances (with a relative excess of dietary fat and protein intake with associated dyslipidaemia and increased risk of insulin resistance and T2D development) and ketotic effects. Finally, the LCD often results in a reduction in dietary fibre intake, with potentially serious adverse consequences for overall health and the gut microbiota. CONCLUSIONS: Although widely adopted, the LCD usually has short-lived metabolic benefits, with limited efficacy and practicality over the longer term. Dietary modification needs tailoring to the individual, with careful a priori assessments of food preferences to ensure acceptability and adherence over the longer term, with avoidance of dietary imbalances and optimization of dietary fibre intake (primarily from plant-based fruit and vegetables), and with a posteriori assessments of the highly individual responses to the LCD. Finally, we need to change our view of diets from simply an excipient for weight loss to an essential component of a healthy lifestyle.


Assuntos
Carboidratos/deficiência , Diabetes Mellitus Tipo 2/dietoterapia , Dieta com Restrição de Carboidratos/efeitos adversos , Carboidratos da Dieta/metabolismo , Obesidade/dietoterapia , Diabetes Mellitus Tipo 2/metabolismo , Dieta com Restrição de Carboidratos/métodos , Carboidratos da Dieta/administração & dosagem , Gorduras na Dieta/administração & dosagem , Gorduras na Dieta/efeitos adversos , Proteínas na Dieta/administração & dosagem , Proteínas na Dieta/efeitos adversos , Humanos , Obesidade/metabolismo , Indução de Remissão/métodos , Fatores de Tempo , Resultado do Tratamento , Perda de Peso
5.
Nutr Metab Cardiovasc Dis ; 31(5): 1579-1585, 2021 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-33744041

RESUMO

BACKGROUND AND AIMS: Extensive research showed a diurnal rhythm of endogenous cholesterol synthesis, whereas recent research reported no diurnal rhythm of intestinal cholesterol absorption in males who consumed low-fat meals. Little is known about the acute effect of macronutrient consumption on cholesterol metabolism, and hence if meal composition may explain this absence of rhythmicity in cholesterol absorption. Therefore, we examined the effect of a high-fat, high-carbohydrate, and high-protein meal on postprandial intestinal cholesterol absorption and endogenous cholesterol synthesis in apparently healthy overweight and slightly obese males. METHODS AND RESULTS: Eighteen males consumed in random order an isoenergetic high-fat, high-carbohydrate, and high-protein meal on three occasions. Serum total cholesterol concentrations, cholesterol absorption markers (campesterol, cholestanol, and sitosterol), and cholesterol synthesis intermediates (7-dehydrocholesterol, 7-dehydrodesmosterol, desmosterol, dihydrolanosterol, lanosterol, lathosterol, zymostenol, and zymosterol) were measured at baseline (T0) and 240 min postprandially (T240). Meal consumption did not significantly change total cholesterol concentrations and cholesterol absorption marker levels (all p > 0.05). Serum levels of 7-dehydrocholesterol, lanosterol, lathosterol, zymostenol, and zymosterol decreased significantly between T0 and T240 (all p < 0.05). These decreases were not significantly different between the three meals (all p > 0.05), except for a larger decrease in dihydrolanosterol levels after the high-fat versus the high-carbohydrate meal (p = 0.009). CONCLUSION: The high-fat, high-carbohydrate, and high-protein meal did not significantly influence postprandial intestinal cholesterol absorption. Several cholesterol synthesis intermediates decreased postprandially, but the individual macronutrients did not differentially affect these intermediates, except for a possible effect on dihydrolanosterol. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03139890.


Assuntos
Colesterol/metabolismo , Dieta Hiperlipídica , Dieta Rica em Proteínas , Carboidratos da Dieta/administração & dosagem , Absorção Intestinal , Idoso , Biomarcadores/sangue , Colesterol/biossíntese , Colesterol/sangue , Estudos Cross-Over , Carboidratos da Dieta/metabolismo , Método Duplo-Cego , Ingestão de Energia , Humanos , Masculino , Pessoa de Meia-Idade , Países Baixos , Período Pós-Prandial , Fatores de Tempo
6.
Science ; 371(6535)2021 03 19.
Artigo em Inglês | MEDLINE | ID: mdl-33737460

RESUMO

The intestine is a site of direct encounter with the external environment and must consequently balance barrier defense with nutrient uptake. To investigate how nutrient uptake is regulated in the small intestine, we tested the effect of diets with different macronutrient compositions on epithelial gene expression. We found that enzymes and transporters required for carbohydrate digestion and absorption were regulated by carbohydrate availability. The "on-demand" induction of this machinery required γδ T cells, which regulated this program through the suppression of interleukin-22 production by type 3 innate lymphoid cells. Nutrient availability altered the tissue localization and transcriptome of γδ T cells. Additionally, transcriptional responses to diet involved cellular remodeling of the epithelial compartment. Thus, this work identifies a role for γδ T cells in nutrient sensing.


Assuntos
Carboidratos da Dieta/administração & dosagem , Carboidratos da Dieta/metabolismo , Enterócitos/fisiologia , Interleucinas/metabolismo , Mucosa Intestinal/fisiologia , Receptores de Antígenos de Linfócitos T gama-delta , Subpopulações de Linfócitos T/fisiologia , Adaptação Fisiológica , Animais , Comunicação Celular , Proteínas na Dieta/administração & dosagem , Digestão , Regulação da Expressão Gênica , Interleucinas/genética , Absorção Intestinal , Mucosa Intestinal/citologia , Intestino Delgado/citologia , Intestino Delgado/metabolismo , Camundongos Endogâmicos C57BL , Nutrientes/administração & dosagem , Nutrientes/metabolismo , Subpopulações de Linfócitos T/imunologia , Transcrição Genética , Transcriptoma
7.
Nutrients ; 13(2)2021 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-33540813

RESUMO

Endurance athletes need a regular and well-detailed nutrition program in order to fill their energy stores before training/racing, to provide nutritional support that will allow them to endure the harsh conditions during training/race, and to provide effective recovery after training/racing. Since exercise-related gastrointestinal symptoms can significantly affect performance, they also need to develop strategies to address these issues. All these factors force endurance athletes to constantly seek a better nutritional strategy. Therefore, several new dietary approaches have gained interest among endurance athletes in recent decades. This review provides a current perspective to five popular diet approaches: (a) vegetarian diets, (b) high-fat diets, (c) intermittent fasting diets, (d) gluten-free diet, and (e) low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) diets. We reviewed scientific studies published from 1983 to January 2021 investigating the impact of these popular diets on the endurance performance and health aspects of endurance athletes. We also discuss all the beneficial and harmful aspects of these diets, and offer key suggestions for endurance athletes to consider when following these diets.


Assuntos
Atletas , Desempenho Atlético/fisiologia , Dieta/tendências , Fenômenos Fisiológicos da Nutrição Esportiva/fisiologia , Esportes/fisiologia , Dieta/efeitos adversos , Dieta Livre de Glúten , Dieta Hiperlipídica , Dieta Vegetariana , Carboidratos da Dieta/administração & dosagem , Carboidratos da Dieta/metabolismo , Jejum , Fermentação , Gastroenteropatias/etiologia , Gastroenteropatias/prevenção & controle , Humanos , Necessidades Nutricionais , Resistência Física
8.
Nutr Metab Cardiovasc Dis ; 31(4): 1238-1246, 2021 04 09.
Artigo em Inglês | MEDLINE | ID: mdl-33632598

RESUMO

BACKGROUND AND AIMS: During aerobic physical activity (PA), hypoglycemia is common in people with type 1 diabetes (T1D). Few studies have compared the effectiveness of different carbohydrate (CHO) intake strategies to prevent PA-induced hypoglycemia. Our objective was to compare the efficacy of two CHO intake strategies, same total amount but different CHO intake timing, to maintain glucose levels in the target range (4.0-10.0 mmol/L) during PA in people with T1D. METHODS AND RESULTS: An open-label, randomized, crossover study in 33 participants (21 adults; 12 adolescents). Participants practiced 60 min PA sessions (ergocyle) at 60% VO2peak 3.5 h after lunch comparing an intake of 0.5 g of CHO per kg of body weight applied in a pre-PA single CHO intake (SCI) or in a distributed CHO intake (DCI) before and during PA. The percentage of time spent in glucose level target range during PA was not different between the two strategies (SCI: 75 ± 35%; DCI: 87 ± 26%; P = 0.12). Hypoglycemia (<4.0 mmol/L) occurred in 4 participants (12%) with SCI compared to 6 participants (18%) with DCI (P = 0.42). The SCI strategy led to a higher increase (P = 0.01) and variability of glucose levels (P = 0.04) compared with DCI. CONCLUSIONS: In people living with T1D, for a 60 min moderate aerobic PA in the post-absorptive condition, a 0.5 g/kg CHO intake helped most participants maintain acceptable glycemic control with both strategies. No clinically significant difference was observed between the SCI and DCI strategies. ClinicalTrials.gov Identifier: NCT03214107 (July 11, 2017).


Assuntos
Glicemia/metabolismo , Diabetes Mellitus Tipo 1/dietoterapia , Carboidratos da Dieta/administração & dosagem , Exercício Físico , Controle Glicêmico , Hipoglicemia/prevenção & controle , Adolescente , Adulto , Fatores Etários , Biomarcadores/sangue , Estudos Cross-Over , Diabetes Mellitus Tipo 1/sangue , Diabetes Mellitus Tipo 1/diagnóstico , Carboidratos da Dieta/metabolismo , Feminino , Hemoglobina A Glicada/metabolismo , Humanos , Hipoglicemia/sangue , Hipoglicemia/etiologia , Masculino , Pessoa de Meia-Idade , Quebeque , Fatores de Tempo , Resultado do Tratamento
9.
Food Funct ; 12(3): 1051-1062, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33443255

RESUMO

We analysed the influence of obesity, sex and sex steroids on the postprandial responses of circulating energy homeostasis mediators and their receptors to different macronutrient challenges. Seventeen women with polycystic ovary syndrome (PCOS, 8 with obesity), 17 non-hyperandrogenic control women (8 with obesity) and 19 control men (9 with obesity) were submitted, on alternate days, to isocaloric (300 kcal) oral glucose, lipid and protein loads. We evaluated serum ghrelin, leptin, soluble leptin receptor and adiponectin levels and the leukocyte gene expression of ghrelin (GHRL) and its receptor (GHSR), leptin receptor (LEPR) and adiponectin receptor 1 (ADIPOR1) during the macronutrient challenges. The postprandial responses of circulating energy homeostasis mediators were entirely different than those of their related genes. After macronutrient loads the postprandial response of serum energy homeostasis mediators showed a generalized physiological decrease that was blunted in subjects with obesity but was not influenced by sex, sex hormones or PCOS. However, gene expression of GHRL, LEPR and ADIPOR1 showed a marked increase following the ingestion of glucose compared with lipids and proteins, regardless of obesity and sex steroids. The physiological decrease after macronutrient loads, that was deregulated in obesity, did not reflect the acute leukocyte gene expression mainly after glucose, and may suggest a possible role for ghrelin, leptin and adiponectin in the postprandial inflammatory process.


Assuntos
Metabolismo Energético/fisiologia , Hormônios Esteroides Gonadais/metabolismo , Homeostase/fisiologia , Nutrientes/metabolismo , Obesidade/metabolismo , Período Pós-Prandial , Adulto , Área Sob a Curva , Carboidratos da Dieta/metabolismo , Carboidratos da Dieta/farmacologia , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Hormônios Esteroides Gonadais/sangue , Humanos , Leptina/sangue , Leptina/metabolismo , Leucócitos/efeitos dos fármacos , Leucócitos/metabolismo , Masculino , Receptores para Leptina/genética , Receptores para Leptina/metabolismo , Adulto Jovem
10.
Nat Med ; 27(2): 344-353, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33479499

RESUMO

The carbohydrate-insulin model of obesity posits that high-carbohydrate diets lead to excess insulin secretion, thereby promoting fat accumulation and increasing energy intake. Thus, low-carbohydrate diets are predicted to reduce ad libitum energy intake as compared to low-fat, high-carbohydrate diets. To test this hypothesis, 20 adults aged 29.9 ± 1.4 (mean ± s.e.m.) years with body mass index of 27.8 ± 1.3 kg m-2 were admitted as inpatients to the National Institutes of Health Clinical Center and randomized to consume ad libitum either a minimally processed, plant-based, low-fat diet (10.3% fat, 75.2% carbohydrate) with high glycemic load (85 g 1,000 kcal-1) or a minimally processed, animal-based, ketogenic, low-carbohydrate diet (75.8% fat, 10.0% carbohydrate) with low glycemic load (6 g 1,000 kcal-1) for 2 weeks followed immediately by the alternate diet for 2 weeks. One participant withdrew due to hypoglycemia during the low-carbohydrate diet. The primary outcomes compared mean daily ad libitum energy intake between each 2-week diet period as well as between the final week of each diet. We found that the low-fat diet led to 689 ± 73 kcal d-1 less energy intake than the low-carbohydrate diet over 2 weeks (P < 0.0001) and 544 ± 68 kcal d-1 less over the final week (P < 0.0001). Therefore, the predictions of the carbohydrate-insulin model were inconsistent with our observations. This study was registered on ClinicalTrials.gov as NCT03878108 .


Assuntos
Metabolismo Energético/fisiologia , Insulina/metabolismo , Obesidade/metabolismo , Sobrepeso/metabolismo , Adulto , Composição Corporal , Índice de Massa Corporal , Dieta com Restrição de Gorduras/efeitos adversos , Dieta Cetogênica/efeitos adversos , Dieta Vegetariana/efeitos adversos , Carboidratos da Dieta/metabolismo , Gorduras na Dieta/metabolismo , Ingestão de Energia , Feminino , Humanos , Insulina/genética , Masculino , Pessoa de Meia-Idade , Obesidade/dietoterapia , Obesidade/epidemiologia , Obesidade/patologia , Sobrepeso/dietoterapia , Sobrepeso/epidemiologia , Perda de Peso
11.
Pediatr. aten. prim ; 22(88): 371-378, oct.-dic. 2020. tab
Artigo em Espanhol | IBECS | ID: ibc-201440

RESUMO

INTRODUCCIÓN: la elevada prevalencia de la obesidad en las edades pediátricas plantea el desarrollo de comorbilidades, dentro de las cuales se encuentran las alteraciones glucídicas. OBJETIVO: determinar si existe alteración glucídica en pacientes pediátricos con obesidad. MATERIAL Y MÉTODO: estudio descriptivo, transversal, en 76 pacientes pediátricos con diagnóstico de obesidad atendidos en el Servicio de Endocrinología del Hospital Juan Manuel Márquez (La Habana, Cuba), en el periodo de enero de 2015 a enero de 2019. Las variables en estudio fueron: edad, sexo, tipo de prediabetes, tiempo de evolución y grado de obesidad. Las variables cualitativas se describieron estadísticamente mediante frecuencias absolutas y relativas, la asociación entre las variables categóricas se exploró con el test χ2 y la probabilidad exacta de Fisher. En todas las pruebas estadísticas se consideró un nivel de significación de alfa igual a 0,05. RESULTADOS: el 71,05% de los pacientes presentaron prediabetes, de los cuales el 40,59% pertenecían al sexo femenino y el 72,22% eran mayores de 10 años de edad. Predominaron los pacientes con TGA (70,37%), de los cuales el 50,0% eran mayores de 10 años de edad y el 37,04% eran del sexo femenino. El tiempo de evolución de la obesidad no resultó significativo y se constató un incremento de la prediabetes a mayor grado de la obesidad (p = 0,0095). CONCLUSIONES: se presentaron alteraciones del metabolismo de los hidratos de carbono expresadas por la presencia de prediabetes. Predominó el sexo femenino. No existió asociación entre la prediabetes con el tiempo de evolución de la obesidad, pero sí con el grado de obesidad


INTRODUCTION: high prevalence of obesity in the paediatric population carries a risk of development of comorbidities, including abnormal blood glucose levels. OBJECTIVE: to determine whether abnormal blood glucose levels are present in paediatric patients with obesity. MATERIAL AND METHODS: we conducted a cross-sectional descriptive study in 76 paediatric patients with a diagnosis of obesity managed in the Department of Endocrinology of the Juan Manuel Márquez hospital (Havana, Cuba) between January 2015 and January 2019. The variables under study were: age, sex, type of prediabetes, duration and severity of obesity. We described qualitative variables as absolute and relative frequencies and analysed the association between categorical variables with the χ2 and Fisher exact tests. We defined statistical significance as an alpha probability of 0.05. RESULTS: we found that 71.05% of the patients in the sample had prediabetes, of who 40.59% were female and 72.22% aged more than 10 years. There was a predominance of patients with impaired glucose tolerance (70.37%), of who 50.0% were older than 10 years and 37.04% female. We did not find a significant association between the duration of obesity and prediabetes, but we found an increase in prediabetes with increasing severity of obesity (p = 0.0095). CONCLUSIONS: we found abnormalities in carbohydrate metabolism manifesting as prediabetes. The prevalence was higher in female patients. We did not find a significant association between the duration of obesity and prediabetes, but we found an increase in prediabetes with increasing severity of obesity


Assuntos
Humanos , Masculino , Feminino , Lactente , Pré-Escolar , Criança , Adolescente , Metabolismo dos Carboidratos , Carboidratos da Dieta/metabolismo , Estado Pré-Diabético/metabolismo , Obesidade/metabolismo , Índice de Gravidade de Doença , Estudos Transversais
12.
Nutr. hosp ; 37(5): 1022-1027, sept.-oct. 2020. graf
Artigo em Inglês | IBECS | ID: ibc-198018

RESUMO

Low-carbohydrate diets are frequently used to improve performance in endurance sports, often with contradictory results. This study aimed to assess whether a low-carbohydrate diet can outperform an isocaloric conventional diet for improving body composition and performance in a sample of twenty-six trained male road cyclists (previous experience in cyclosportive events, 7.6 ± 4.4 years; age, 26.9 ± 4.9 years; weekly training volume, 7.8 ± 2.9 hours; height, 176 ± 7 centimeters; body fat percentage, 9.7 ± 0.8 %; weight, 65.3 ± 2.3 kg). Detraining and pretreatment periods in which nutrition and training were standardized were followed by an eight-week long intervention in which cyclists consumed either a low-carbohydrate diet (15 % of calories from carbohydrates) or a conventional endurance sports diet while maintaining the same training volumes and intensities. Body composition was assessed through electrical impedance, and performance was evaluated through a twenty-minute time trial performed on a smart bike trainer. The results revealed an overall improvement over time in absolute and relative power, body mass, and body fat for both groups, whilst the improvement in absolute power was comparable. The improvements seen in relative power (p = 0.042), body mass (p = 0.006), and body fat (p = 0.01) were significantly higher in the low-carbohydrate group. We concluded that eight weeks of a low-carbohydrate diet significantly reduced body weight and body fat percentage, and improved 20-minute relative power values in a sample of road cyclists when compared to an isocaloric conventional diet


Las dietas bajas en carbohidratos se usan con frecuencia para mejorar el rendimiento en los deportes de resistencia, a menudo con resultados contradictorios. Este estudio tuvo como objetivo evaluar si una dieta baja en carbohidratos puede superar a una dieta convencional isocalórica para mejorar la composición corporal y el rendimiento en una muestra de veintiséis ciclistas de carretera masculinos entrenados (experiencia previa en eventos cicloportivos, 7,6 ± 4,4 años; edad, 26,9 ± 4,9 años; volumen de entrenamiento semanal, 7,8 ± 2,9 horas; altura, 176 ± 7 centímetros; porcentaje de grasa corporal, 9,7 ± 0,8 %; peso, 65,3 ± 2,3 kg). Los períodos de desentrenamiento y pretratamiento, en los que se estandarizaron la nutrición y el entrenamiento, fueron seguidos por una intervención de ocho semanas de duración en la que los ciclistas consumieron una dieta de bajo contenido en carbohidratos (15 % de calorías de los carbohidratos) o una dieta convencional para deportes de resistencia, manteniendo los mismos volúmenes de entrenamiento e intensidades. La composición corporal se evaluó a través de la impedancia eléctrica y el rendimiento se evaluó a través de una prueba contrarreloj de veinte minutos realizada en un rodillo de bicicleta inteligente. Los resultados revelaron una mejora general en el tiempo en cuanto a potencia absoluta y relativa, masa corporal y grasa corporal para ambos grupos, mientras que la mejora en potencia absoluta fue comparable. Las mejoras de la potencia relativa (p = 0,042), la masa corporal (p = 0,006) y la grasa corporal (p = 0,01) fueron significativamente mayores en el grupo bajo en carbohidratos. Se concluye que ocho semanas de una dieta baja en carbohidratos redujeron significativamente el peso corporal y el porcentaje de grasa corporal, y mejoraron los valores de potencia relativa de 20 minutos en una muestra de ciclistas de carretera en comparación con una dieta convencional isocalórica


Assuntos
Humanos , Masculino , Adulto Jovem , Adulto , Carboidratos da Dieta/administração & dosagem , Carboidratos da Dieta/metabolismo , Composição Corporal/fisiologia , Desempenho Atlético/fisiologia , Ciclismo/fisiologia , Fenômenos Fisiológicos da Nutrição Animal , Impedância Elétrica , Índice de Massa Corporal , Dieta , Atletas
13.
Sports Health ; 12(4): 382-389, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32520660

RESUMO

BACKGROUND: Sport concussion (SC) causes an energy crisis in the brain by increasing energy demand, decreasing energy supply, and altering metabolic resources. Whole-body resting metabolic rate (RMR) is elevated after more severe brain injuries, but RMR changes are unknown after SC. The purpose of this study was to longitudinally examine energy-related changes in collegiate athletes after SC. HYPOTHESIS: RMR and energy consumption will increase acutely after SC and will return to control levels with recovery. STUDY DESIGN: Case-control study. LEVEL OF EVIDENCE: Level 4. METHODS: A total of 20 collegiate athletes with SC (mean age, 19.3 ± 1.08 years; mean height, 1.77 ± 0.11 m; mean weight, 79.6 ± 23.37 kg; 55% female) were compared with 20 matched controls (mean age, 20.8 ± 2.17 years; mean height, 1.77 ± 0.10 m; mean weight, 81.9 ± 23.45 kg; 55% female). RMR, percentage carbohydrate use (%CHO), and energy balance (EBal; ratio between caloric consumption and expenditure) were assessed 3 times: T1, ≤72 hours after SC; T2, 7 days after T1; and TF, after symptom resolution. A 2 × 2 × 3 (group × sex × time) multivariate analysis of variance assessed RMR, %CHO, and EBal. Changes in RMR, %CHO, and EBal (T1 to TF) were correlated with days to symptom-free and days to return to play in the concussed group. RESULTS: Women reported being symptom-free (median, 6 days; range, 3-10 days) sooner than men (median, 11 days; range, 7-16 days). RMR and %CHO did not differ across time between groups or for group × sex interaction. SC participants had higher EBal than controls at T1 (P = 0.016) and T2 (P = 0.010). In men with SC, increasing %CHO over time correlated with days to symptom-free (r = 0.735 and P = 0.038, respectively) and days to return to play (r = 0.829 and P = 0.021, respectively). CONCLUSION: Participants with SC were in energy surplus acutely after injury. Although women recovered more quickly than men, men had carbohydrate metabolism changes that correlated with recovery time. CLINICAL RELEVANCE: This pilot study shows that male and female student-athletes may have differing physiologic responses to SC and that there may be a role for dietary intervention to improve clinical outcomes after SC.


Assuntos
Traumatismos em Atletas/metabolismo , Metabolismo Basal , Concussão Encefálica/metabolismo , Carboidratos da Dieta/metabolismo , Ingestão de Energia , Metabolismo Energético , Feminino , Humanos , Masculino , Projetos Piloto , Fatores Sexuais , Adulto Jovem
14.
Am J Clin Nutr ; 112(2): 284-292, 2020 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-32537643

RESUMO

BACKGROUND: Lower carbohydrate diets have the potential to improve glycemia but may increase ketonemia in women with gestational diabetes (GDM). We hypothesized that modestly lower carbohydrate intake would not increase ketonemia. OBJECTIVE: To compare blood ketone concentration, risk of ketonemia, and pregnancy outcomes in women with GDM randomly assigned to a lower carbohydrate diet or routine care. METHODS: Forty-six women aged (mean ± SEM) 33.3 ± 0.6 y and prepregnancy BMI 26.8 ± 0.9 kg/m2 were randomly assigned at 28.5 ± 0.4 wk to a modestly lower carbohydrate diet (MLC, ∼135 g/d carbohydrate) or routine care (RC, ∼200 g/d) for 6 wk. Blood ketones were ascertained by finger prick test strips and 3-d food diaries were collected at baseline and end of the intervention. RESULTS: There were no detectable differences in blood ketones between completers in the MLC group compared with the RC group (0.1 ± 0.0 compared with 0.1 ± 0.0 mmol/L, n = 33, P = 0.31, respectively), even though carbohydrate and total energy intake were significantly lower in the intervention group (carbohydrate 165 ± 7 compared with 190 ± 9 g, P = 0.04; energy 7040 ± 240 compared with 8230 ± 320 kJ, P <0.01, respectively). Only 20% of participants in the MLC group met the target intake compared with 65% in the RC group (P <0.01). There were no differences in birth weight, rate of large-for-gestational-age infants, percent fat mass, or fat-free mass between groups. CONCLUSIONS: An intervention to reduce carbohydrate intake in GDM did not raise ketones to clinical significance, possibly because the target of 135 g/d was difficult to achieve in pregnancy. Feeding studies with food provision may be needed to assess the benefits and risks of low-carbohydrate diets. This trial was registered at www.anzctr.org.au as ACTRN12616000018415.


Assuntos
Diabetes Gestacional/dietoterapia , Dieta com Restrição de Carboidratos , Adulto , Glicemia/metabolismo , Índice de Massa Corporal , Diabetes Gestacional/metabolismo , Carboidratos da Dieta/análise , Carboidratos da Dieta/metabolismo , Ingestão de Energia , Feminino , Índice Glicêmico , Humanos , Gravidez
15.
PLoS One ; 15(6): e0233364, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32530969

RESUMO

Type 2 diabetes mellitus (T2DM) is among the most prevalent diseases in the world, affecting over 420 million people. The disease is marked by a poor metabolic effect of insulin leading to chronic hyperglycaemia, which can result in microvascular complications. It is widely known that postprandial glycaemia is reliant on the total carbohydrate content of a meal. However, the importance of the amount and the source of these carbohydrates remains controversial due to mechanisms other than insulin secretion. Oxidative stress, inflammation, pyruvate production and the quality of the intestinal microbiota, resulting in plasma lipopolysaccharides and short-chain fatty acids production, play an important role in blood sugar control and consequently in type 2 diabetes. Thus, we systematically reviewed the preclinical evidences on the impact of the amount and type of carbohydrate found in different diets and its influence on blood glucose levels in diabetic animals. We used a comprehensive and structured search in biomedical databases Medline (PubMed), Scopus and Web of Science, recovering and analyzing 27 original studies. Results showed that sucrose-rich diets deteriorated diabetic condition in animal models regardless of the total dietary carbohydrate content. On the other hand, fiber, particularly resistant starch, improved blood glucose parameters through direct and indirect mechanisms, such as delayed gastric emptying and improved gut microbiota. All studies used rodents as animal models and male animals were preferred over females. Improvements in T2DM parameters in animal models were more closely related to the type of dietary carbohydrate than to its content on a diet, i. e., resistant starch seems to be the most beneficial source for maintaining normoglycemia. Results show that current literature is at high risk of bias due to neglecting experimental methods.


Assuntos
Diabetes Mellitus Tipo 2/dietoterapia , Carboidratos da Dieta/análise , Animais , Glicemia/metabolismo , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/metabolismo , Dieta/métodos , Carboidratos da Dieta/metabolismo , Fibras na Dieta/metabolismo , Sacarose na Dieta/metabolismo , Modelos Animais de Doenças , Feminino , Humanos , Insulina/metabolismo , Secreção de Insulina/efeitos dos fármacos , Masculino , Período Pós-Prandial/fisiologia , Triglicerídeos/sangue
16.
PLoS One ; 15(6): e0234344, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32502191

RESUMO

Nitrogen (N) isotopic discrimination (i.e. the difference in natural 15N abundance between the animal proteins and the diet; Δ15N) is known to correlate with N use efficiency (NUE) and feed conversion efficiency (FCE) in ruminants. However, results from the literature are not always consistent across studies, likely due to isotopic discrimination pathways that may differ with the nature of diets. The objective of the present study was to assess at which level, from rumen to tissues, Δ15N originates and becomes related to NUE and FCE in fattening yearling bulls when they are fed two contrasted diets. Twenty-four Charolais yearling bulls were randomly divided into two groups and fed during 8 months, from weaning to slaughter, either 1) a high starch diet based on corn silage supplying a balanced N to energy ratio at the rumen level (starch) or 2) a high fiber diet based on grass silage supplying an excess of rumen degradable N (fiber). All animals were slaughtered and samples of different digestive pools (ruminal, duodenal, ileal and fecal contents), animal tissues (duodenum, liver and muscle), blood and urine were collected for each animal. Ruminal content was further used to isolate liquid-associated bacteria (LAB), protozoa and free ammonia, while plasma proteins were obtained from blood. All samples along with feed were analyzed for their N isotopic composition. For both diets, the digestive contribution (i.e. the N isotopic discrimination occurring before absorption) to the Δ15N observed in animal tissues accounted for 65 ± 11%, leaving only one third to the contribution of post-absorptive metabolism. Concerning the Δ15N in digestive pools, the majority of these changes occurred in the rumen (av. Δ15N = 2.12 ± 0.66‰), with only minor 15N enrichments thereafter (av. Δ15N = 2.24 ± 0.41‰), highlighting the key role of the rumen on N isotopic discrimination. A strong, significant overall relationship (n = 24) between Δ15N and FCE or NUE was found when using any post-absorptive metabolic pool (duodenum, liver, or muscle tissues, or plasma proteins; 0.52 < r < 0.73; P ≤ 0.01), probably as these pools reflect both digestive and post-absorptive metabolic phenomena. Fiber diet compared to starch diet had a lower feed efficiency and promoted higher (P ≤ 0.05) Δ15N values across all post-absorptive metabolic pools and some digestive pools (ruminal, duodenal, and ileal contents). The within-diet relationship (n = 12) between Δ15N and feed efficiency was not as strong and consistent as the overall relationship, with contrasted responses between the two diets for specific pools (diet x pool interaction; P ≤ 0.01). Our results highlight the contrasted use of N at the rumen level between the two experimental diets and suggests the need for different equations to predict FCE or NUE from Δ15N according to the type of diet. In conclusion, rumen digestion and associated microbial activity can play an important role on N isotopic discrimination so rumen effect related to diet may interfere with the relationship between Δ15N and feed efficiency in fattening yearling bulls.


Assuntos
Ração Animal/análise , Dieta/métodos , Nitrogênio/metabolismo , Fenômenos Fisiológicos da Nutrição Animal/fisiologia , Animais , Bovinos , Carboidratos da Dieta/metabolismo , Fibras na Dieta/metabolismo , Digestão/fisiologia , Fezes/química , Masculino , Rúmen/microbiologia , Ruminantes/metabolismo , Amido/metabolismo
17.
PLoS One ; 15(5): e0232689, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32384105

RESUMO

Bacteria residing in the gastrointestinal tract of mammals are crucial for the digestion of dietary nutrients. Bacterial community composition is modified by age and diet in other species. Although horses are adapted to consuming fibre-based diets, high-energy, often high-starch containing feeds are increasingly used. The current study assessed the impact of age on the faecal bacteriome of ponies transitioning from a hay-based diet to a high-starch diet. Over two years, 23 Welsh Section A pony mares were evaluated (Controls, 5-15 years, n = 6/year, 12 in total; Aged, ≥19 years, n = 6 Year 1; n = 5 Year 2, 11 in total). Across the same 30-week (May to November) period in each year, animals were randomly assigned to a 5-week period of study and were individually fed the same hay to maintenance (2% body mass as daily dry matter intake) for 4-weeks. During the final week, 2g starch per kg body mass (micronized steam-flaked barley) was incorporated into the diet (3-day transition and 5 days at maximum). Faecal samples were collected for 11 days (final 3 days hay and 8 days hay + barley feeding). Bacterial communities were determined using Ion Torrent Sequencing of amplified V1-V2 hypervariable regions of 16S rRNA. Age had a minimal effect on the bacteriome response to diet. The dietary transition increased Candidatus Saccharibacteria and Firmicutes phyla abundance and reduced Fibrobactres abundance. At the genera level, Streptococcus abundance was increased but not consistently across individual animals. Bacterial diversity was reduced during dietary transition in Streptococcus 'responders'. Faecal pH and VFA concentrations were modified by diet but considerable inter-individual variation was present. The current study describes compositional changes in the faecal bacteriome associated with the transition from a fibre-based to a high-starch diet in ponies and emphasises the individual nature of dietary responses, which may reflect functional differences in the bacterial populations present in the hindgut.


Assuntos
Ração Animal , Carboidratos da Dieta/metabolismo , Microbioma Gastrointestinal , Cavalos/fisiologia , Amido/metabolismo , Envelhecimento , Ração Animal/análise , Animais , Carboidratos da Dieta/análise , Fibras na Dieta/análise , Fibras na Dieta/metabolismo , Fezes/microbiologia , Glucose/metabolismo , Insulina/metabolismo , Amido/análise
18.
J Anim Sci ; 98(6)2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32447367

RESUMO

Cattle need physically effective fiber to promote rumination and maintain rumen health, but economics favor the use of low-roughage feedlot diets. The study investigated the optimum barley silage proportion in barley-based finishing diets. Apparent total-tract digestibility (4-d total fecal collection), chewing behavior (6-d video recording), ruminal pH (6-d indwelling pH recording), and fermentation (1 day, sampling 0, 3, 6, 12, and 18 h postfeeding), short-chain fatty acid (SCFA) absorption (washed reticulo-rumen technique), gastrointestinal tract barrier function (marker infusion), and blood variables (catheters) were measured. Eight ruminally fistulated crossbred beef heifers (653 ± 44.2 kg; mean starting body weight [BW] ± SD) were used in a replicated 4 × 4 Latin square design with 28-d periods. Dietary treatments were 0%, 4%, 8%, and 12% of dietary dry matter (DM) as barley silage, with diets containing 80%, 76%, 72%, and 68% barley grain, respectively. Increasing silage proportion decreased dietary starch content from 49.0% to 43.1% DM, while neutral detergent content increased from 22.7% to 25.1% DM. Silage proportion had no effect on DM intake, but apparent DM digestibility decreased quadratically (86.0%, 82.1%, 81.1%, 79.5% for the four diets, respectively; P < 0.001). Although, silage proportion had no effect on eating activity, rumination time increased quadratically (246, 289, 302, 316 min/d; P = 0.04). Increased silage proportion increased minimum (5.07, 5.27, 5.29, 5.41; quadratic, P = 0.011) and mean (5.61, 5.87, 5.93, 5.95; quadratic, P = 0.007) ruminal pH, and there was a quadratic (P ≤ 0.047) decrease in duration and area under the pH acidosis threshold curves of 5.8, 5.5, and 5.2. Although increasing silage proportion decreased ruminal acidosis, it was not completely eliminated even with a diet containing 12% silage DM. SCFA concentration in ruminal fluid was not affected by diet, but silage proportion quadratically (P ≤ 0.088) increased ruminal acetate:propionate. There was no effect of diet on absolute or fractional rates of absorption of acetate, propionate, butyrate or total SCFA, and no effect on gastrointestinal barrier function or blood measurements. In conclusion, responses to roughage level were mostly quadratic with greatest improvements in acidosis variables between 0% and 4% barley silage, with incremental improvements with further increases in silage levels. The study showed a trade-off between maximizing digestibility and energy intake to promote animal performance and minimizing the risk of acidosis.


Assuntos
Acidose/veterinária , Doenças dos Bovinos/metabolismo , Fibras na Dieta/análise , Ácidos Graxos Voláteis/metabolismo , Acidose/metabolismo , Animais , Bovinos , Dieta/veterinária , Carboidratos da Dieta/metabolismo , Digestão , Feminino , Fermentação , Trato Gastrointestinal/metabolismo , Hordeum , Concentração de Íons de Hidrogênio , Nutrientes/metabolismo , Rúmen/metabolismo , Silagem/análise
19.
Am J Clin Nutr ; 112(1): 180-186, 2020 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-32297956

RESUMO

BACKGROUND: The optimal macronutrient composition of the diet is controversial and many adults attempt to regulate the intake of specific macronutrients for various health-related reasons. OBJECTIVE: The objective was to compare stability and ranges of intakes of different macronutrients across diverse adult populations in the USA and globally. METHODS: US dietary intake data from NHANES 2009-2014 were used to determine macronutrient intake as a percentage of total energy intake. Variability in macronutrient intake was estimated by calculating the difference between 75th and 25th percentile (Q3-Q1) IQRs of macronutrient intake distributions. In addition, intake data from 13 other countries with per capita gross domestic product (GDP) over $10,000 US dollars (USD) were used to assess variability of intake internationally since there are large differences in types of foods consumed in different countries. RESULTS: Protein, carbohydrate, and fat intake (NHANES 2009-2014) was 15.7 ± 0.1, 48.1 ± 0.1, and 32.9 ± 0.1% kcal, respectively, in US adults. The IQR of protein intake distribution (3.73 ± 0.11% kcal) was 41% of carbohydrate intake distribution (9.18 ± 0.20% kcal) and 58% of fat intake distribution (6.40 ± 0.14% kcal). The IQRs of carbohydrate and fat intake distributions were significantly (P <0.01) influenced by age and race; however, the IQR of protein intake was not associated with demographic and lifestyle factors including sex, race, income, physical activity, and body weight. International mean protein intake was 16.3 ± 0.2% kcal, similar to US intake, and there was less variation in protein than carbohydrate or fat intake. CONCLUSION: Protein intake of the US population and multiple international populations, regardless of demographic and lifestyle factors, was consistently ∼16% of total energy, suggesting biological control mechanism(s) tightly regulate protein intake and, consequently, influence intake of other macronutrients and food constituents. Substantial differences in intake of the other macronutrients observed in US and international populations had little influence on protein intake. This trial was registered at the ISRCTN registry as ISRCTN46157745 (https://www.isrctn.com/ISRCTN4615774).


Assuntos
Carboidratos da Dieta/metabolismo , Proteínas na Dieta/metabolismo , Adulto , Idoso , Peso Corporal , Demografia , Dieta/etnologia , Dieta/estatística & dados numéricos , Ingestão de Energia/etnologia , Exercício Físico , Feminino , Humanos , Estilo de Vida , Masculino , Pessoa de Meia-Idade , Nutrientes/metabolismo , Inquéritos Nutricionais , Estados Unidos/etnologia , Adulto Jovem
20.
Nutrients ; 12(4)2020 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-32252250

RESUMO

Consumption of low-glycemic index (GI) carbohydrates (CHO) may be superior to high-GI CHO before exercise by increasing fat oxidation and decreasing carbohydrate oxidation. We compared the effects of pre-exercise feeding of a low-GI lentil-based sports nutrition bar with a high-GI bar on metabolism and performance during a simulated soccer match. Using a randomized, double-blind, counterbalanced, crossover design, participants (n = 8) consumed 1.5 g/kg available CHO from a low-GI bar (GI = 45) or high-GI bar (GI = 101) two hours before a 90 min simulated soccer match, and 0.38 g/kg body mass during a 15 min half-time break. The test involved alternating 6 min intervals of paced jogging, running, walking, and sprinting, and 3 min intervals of soccer-specific skills (timed ball dribbling, agility running, heading, kicking accuracy). Carbohydrate oxidation rate was lower during the match after consuming the low-GI compared to high-GI bar (2.17 ± 0.6 vs. 2.72 ± 0.4 g/min; p < 0.05). Participants performed better during the low-GI versus high-GI bar condition on the agility test (5.7 ± 0.4 versus 6.1 ± 0.6 s; p < 0.01) and heading (i.e., jumping height 24.7 ± 4.3 versus 22.2 ± 4.5 cm; p < 0.01) late in the soccer match (72 min). A low-GI lentil-based sports nutrition bar provides a metabolic benefit (lower carbohydrate oxidation rate) and a modest improvement in agility running and jumping height (heading) late in the test.


Assuntos
Glicemia/metabolismo , Carboidratos da Dieta/metabolismo , Índice Glicêmico , Futebol , Fenômenos Fisiológicos da Nutrição Esportiva/fisiologia , Adulto , Desempenho Atlético , Estudos Cross-Over , Método Duplo-Cego , Humanos , Masculino , Recreação
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...