RESUMEN
Exercise during pregnancy or lactation may create a competition for glucose between the exercising muscle and either the developing fetus or the lactating mammary gland. To test these two hypotheses, pregnant rats were randomly assigned to isoenergetic diets with varying levels of glucose (20, 40 or 60% by weight) and fat (30, 22 or 14%, respectively, by weight) and were rested (R) or exercised (E) on a motorized treadmill at 20 m/min, 60 min/d (low intensity), 7 d/wk throughout pregnancy and lactation. Main effects and selected interactions of diet and exercise during pregnancy and diet, exercise and litter size during lactation were tested using 3 x 2 and 3 x 2 x 2 factorial designs, respectively. Neither diet nor exercise affected pregnancy outcomes. In contrast, during lactation, milk and mammary gland compositions and pup growth were altered. Exercise produced higher milk protein concentrations (40% glucose diet) and lower milk lactose concentrations (20% glucose diet). Exercise also lowered mammary gland fat content and produced higher milk fat concentrations. The 60% glucose diet resulted in the highest milk fat concentrations, but pups of dams fed the 40% diet were heavier on lactation d 15 than pups of dams fed the 60% diet. Taken together, these results support the claim of decreased availability of glucose to the mammary gland for lactose synthesis during chronic low intensity exercise. Additionally, the best lactation performance was not supported by a high carbohydrate (60% glucose), lower fat (14%) intake. A more moderate carbohydrate (40% glucose), higher fat (22%) intake promoted greater pup weights at weaning, suggesting an overlooked role for macronutrient composition in optimizing lactation performance.
Asunto(s)
Grasas de la Dieta/farmacología , Glucosa/administración & dosificación , Glándulas Mamarias Animales/metabolismo , Leche/química , Condicionamiento Físico Animal/fisiología , Preñez/fisiología , Animales , Animales Recién Nacidos/crecimiento & desarrollo , Sangre/metabolismo , Peso Corporal , Dieta , Desarrollo Embrionario y Fetal/fisiología , Metabolismo Energético/fisiología , Femenino , Feto/fisiología , Glucosa/farmacología , Embarazo , Preñez/sangre , Ratas , Ratas Sprague-DawleyRESUMEN
The diet-heart hypothesis proposes that elevated intakes of total fat, saturated fat, and dietary cholesterol raise serum cholesterol, which in turn increases the risk of developing coronary heart disease (CHD). To examine the relationship between dietary intake and 12-year CHD mortality we used data from the Lipid Research Clinics Prevalence Follow-Up Study. Dietary intake was measured at study entry using the 24-hour recall technique among 4546 North American men and women who were at least 30 years old and initially free of CHD. Proportional hazards analyses controlling for total energy intake indicated that increasing percentages of energy intake as total fat (RR 1.04, 95% CI = 1.01-1.08), saturated fat (RR 1.11, CI = 1.04-1.18), and monounsaturated fat (RR 1.08, CI = 1.01-1.16) were significant risk factors for CHD mortality among 30 to 59 year olds. The increasing percentage of energy intake from carbohydrate had a significant protective effect (RR 0.96, CI = 0.94-0.99). The strength of these associations was not diminished after adjustment for specific serum lipids, suggesting that serum lipids did not mediate the effect of diet on CHD mortality. None of the dietary components were significantly associated with CHD mortality among those aged 60-79 years. We conclude that future research must be directed toward better understanding the pathway between dietary intake and coronary disease as the current diet-lipid-heart hypothesis may be overly simplistic.
Asunto(s)
Enfermedad Coronaria/etiología , Enfermedad Coronaria/mortalidad , Grasas de la Dieta/efectos adversos , Ingestión de Energía , Adulto , Anciano , Colesterol/sangre , Enfermedad Coronaria/sangre , Encuestas sobre Dietas , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Prevalencia , Modelos de Riesgos Proporcionales , Riesgo , Factores de RiesgoRESUMEN
OBJECTIVE: To evaluate the ability of doctors in primary care to assess risk patients' risk of coronary heart disease. DESIGN: Questionnaire survey. SETTING: Continuing medical education meetings, Ontario and Quebec, Canada. SUBJECTS: Community based doctors who agreed to enroll in the coronary health assessment study. MAIN OUTCOME MEASURE: Ratings of coronary risk factors and estimates by doctors of relative and absolute coronary risk of two hypothetical patients and the "average" 40 year old Canadian man and 70 year old Canadian woman. RESULTS: 253 doctors answered the questionnaire. For 30 year olds the doctors rated cigarette smoking as the most important risk factor and raised serum triglyceride concentrations as the least important; for 70 year old patients they rated diabetes as the most important risk factor and raised serum triglyceride concentrations as the least important. They rated each individual risk factor as significantly less important for 70 year olds than for 30 year olds (all risk factors, P < 0.001). They showed a strong understanding of the relative importance of specific risk factors, and most were confident in their ability to estimate coronary risk. While doctors accurately estimated the relative risk of a specific patient (compared with the average adult) they systematically overestimated the absolute baseline risk of developing coronary disease and the risk reductions associated with specific interventions. CONCLUSIONS: Despite guidelines on targeting patients at high risk of coronary disease accurate assessment of coronary risk remains difficult for many doctors. Additional strategies must be developed to help doctors to assess better their patients' coronary risk.