oa Dietary composition and postprandial inflammation: Implications for human health

Inflammation, in general, has been found to be associated with many human health complications. Postprandial inflammation, provoked soon after ingesting a meal, is transient in duration, but with dreadful consequences on human health over a period of time depending on the compositions of the meal. However, many populations, particularly in the Western countries, are in a constant postprandial state, which is likely to initiate insulin resistance (IR) resulting in type 2 diabetes mellitus (T2DM) and cardiovascular diseases (CVD). Postprandial inflammation is dependent on the food quality and quantity, mostly in terms of its energy/calorie content and its nutritional value. Micronutrients, such as minerals and vitamins, constitute the nutritional value of a food, while macronutrients, such as carbohydrate, protein and fat/lipid, are basically the sources of its energy/calorie content. Since energy content varies significantly between carbohydrates (4 kcal/g) and fats (9 kcal/g), the objective is, therefore, to assess postprandial inflammation of an isocaloric, isonitrogenous high carbohydrate (66%) and low fat (20%) diet (HC) versus a high fat (56%) and low carbohydrate (30%) diet (HF), by measuring diet-induced postprandial thermogenesis (DIPT). Healthy, never-obese, postmenopausal, Caucasian female subjects (n=12) participated in this study for 3 weeks each in a crossover design. Fat-free mass (FFM) and fat mass (FM) were measured by under-water weighing before and after each diet. Resting metabolic rate (RMR) was assessed fasting and for five 40-minute periods over a 6 hours DIPT after ingesting 14.3 kg/FFM of either HC or HF diet. A low respiratory quotient (RQ), during the measurement of DIPT, is usually indicative of lipid peroxidation, an important index of inflammation. RQ after ingesting HC diet was significantly higher in this study, while it was significantly lower for HF diet, thus indicating a higher inflammatory response due to fat. A significant elevation of free fatty acid (FFA) was also observed after ingesting HF diet, which is well-known to be associated in the pathophysiology of T2DM, a significant risk factor for CVD. Further studies are necessary to understand the role of postprandial inflammation in human health.