RESUMO
Salivary cortisol levels and saliva alpha-amylase enzymatic activity are non-invasive markers of hypothalamic-pituitary-adrenal axis and autonomic nervous system related to stress, which could be associated with excessive energy intake in response to stressors. Aim: To describe the diurnal variation of salivary cortisol levels and á-amylase activity in prepubertal girls and to assess their change after meals and physical activity episodes. Subjects and Methods: Nine normal-weight girls aged 8 to 10 years were monitored for 14 hours, from 6:00 AM to 20:00 h. Three standardized meals were administered across the day with a controlled sport competition performed at the end of the day. Saliva samples were drawn upon awakening, 30 min after awakening, before and after lunch, before and after dinner, and before-after the controlled episode of physical activity. Results: A decreasing salivary cortisol diurnal pattern was confirmed, with an initial increase occurring 30 minutes after waking up. An ascending diurnal pattern was observed for salivary amylase activity. Meals significantly increased cortisol levels, with a non-significant trend to increase amylase activity. The magnitude of physical activity during acute exercise was associated with increased salivary amylase activity (rho = 0.84; P <0.01). Cortisol levels were positively correlated with body mass index z scores (rho = 0.87; P <0.01). Conclusions: We confirmed the existence of a diurnal pattern of salivary cortisol levels and á-amylase activity in saliva that is modulated by diet and exercise. Our preliminary results also show that salivary cortisol might be related with body weight...
Assuntos
Humanos , Feminino , Criança , Hidrocortisona/análise , Ingestão de Alimentos/fisiologia , Atividade Motora , Saliva/química , alfa-Amilases Salivares/análise , Antropometria , Pressão Arterial , Ritmo Circadiano , Periodicidade , Exercício Físico , Estudo ObservacionalRESUMO
Se ha observado que alimentos que contienen almidón en cantidades similares pueden generar respuestas glicémicas diferentes. En este trabajo se realizó una revisión bibliográfica tendiente a estudiar uno de los factores que modelaría estas diferencias: el estado físico del almidón contenido en el alimento. Los resultados expuestos indican que el estado físico (que llamaremos microestructura) del almidón es uno de los factores principales a considerar, ya que determinaría cómo y qué fracción del total será digerida, lo cual a su vez determina cómo y cuánto será absorbido para su uso metabólico. Estudios tendientes a una mejor cuantificación, tanto de la microestructura como de la respuesta glicémica y efectos fisiológicos, parecen ser necesarios si se tiene como objetivo el poder diseñar alimentos que cumplan con requerimientos nutricionales específicos.
It has been observed that foods with similar amount of starch can generate different glycemic responses. In the present paper we review the one factor that probably determines these differences: the physical state of starch in food. The literature support the idea that the physical state (called microstructure) of starch is a very important factor because determine the rate and the total amount of glucose that will be released (in the digestion process) for absorption and metabolic use. Many studies relating the microstructure and glycemic response, and its physiological effects, are still needed to make new carbohydrate foods with specific nutritional requirements.
