The effects of prolonged fibre exposure on microbiota gastro intestinal function and energy regulation

原理：进食率下降和一顿饭出现饱腹感是正常的饱腹感。这些变化在肥胖者中减弱，因此放慢进食速度和增加饱腹感可能是控制体重的有效手段，可以通过控制食物结构来实现。纤维补充剂已被证明通过对餐后饱腹感的影响来降低食欲，但也可能有有益的餐内作用。然而，虽然一些纤维可以减少能量摄入，但它们对饱腹感发展的确切影响很少得到测试；也没有对引起任何变化的机制进行系统的分析。由于其不同的物理化学特性和各种生物行为效应，纤维可能是研究食欲过程的有效工具，以促进对饥饿和饱腹感的正常控制的表征。详细研究纤维对饮食和食欲的影响，并开发其各自的特性，可以促进新型体重控制产品的开发。纤维可以影响多种因素，从而影响进食速度、饱腹感和能量摄入。然而，目前的数据受到纤维测试范围的限制，并且方法和结果不一致。研究的重点是（通常是大量的）纤维对餐后饱腹感的影响，很少强调餐内重要的因素。方法：由于增加每餐的份量（而不是吃饭的频率）是过度消费的最重要的组成部分，改变食物结构，特别限制每餐的份量，可能比仅仅以加强每餐之间的饱腹感为目的的操纵更有效。显然，我们需要用标准化的方法对纤维的作用进行更系统的分析，以确定在纳入食物后能够使进食率和饱腹感正常化的纤维，从而使个人能够建立更健康的饮食方式。学生研究纤维对餐内饱腹感和餐后饱腹感发展的作用。实验将采用通用饮食监测设备，连续实时测量饮食情况。材料：该研究将利用不同纤维（抗性淀粉和低聚果糖）的特性来探索它们的食欲抑制功效，以及特定的作用模式（在行为、心理、生理和代谢后果方面）。为了实现这些目标，我们将纤维纳入膳食成分，并实时测量饱腹感和饱腹感的变化。这种方法将允许1)直接测量吃一顿饭的具体后果；2)识别最有效降低食欲的纤维，3)通过特定生物标志物的测量阐明其时间位点和作用模式。这些研究将对了解饱腹感和饱腹感的心理/生物中介，以及通过预防过度消费来帮助减肥的满意、饱腹食物的开发具有直接意义。结果：我们将确定纤维的最佳食欲抑制剂量，并评估其对摄入量的影响；餐中进食、感觉和食欲测量；餐后饱腹感与代偿性摄入；与食欲相关的胃肠肽活性（胃饥饿素、GIP、GLP-1和PYY）；口腔-盲肠运输特异性标志物（C13/H2）；血糖、胰岛素、游离脂肪酸；结肠发酵及肠道菌群改变指标。除了急性实验室研究外，我们将评估纤维富集对每种生物标志物的长期（28 d）影响。

RATIONALE: Declining eating rate and emergence of fullness over a meal defines normal satiation. These changes are attenuated in the obese, hence slowing eating rate and amplifying fullness may be effective means of weight control, and might be achieved by manipulating food structure. Fibre supplements have been shown to reduce appetite through effects on post-prandial satiety, but may also have beneficial intra-meal actions. However, while some fibres can reduce energy intake, their precise effects on the development of fullness have seldom been tested; nor has there been systematic analysis of the mechanisms whereby any changes are induced. Due to their diverse physio-chemical properties and various bio-behavioural effects, fibres may be effective tools for the study of appetite processes, to advance the characterisation of the normal controls of hunger and satiety. Detailed study of fibre effects on eating and appetite, and exploitation of their individual properties may advance the development of novel weight control products. Fibres may affect a variety of factors to influence eating rate, fullness and energy intake. However, current data are limited in the range of fibres tested and by inconsistencies in method and findings. Research has focused on the effects of (often large quantities of) fibres on post-prandial satiety, with little emphasis on important intra-meal factors. APPROACH: As increased meal size (not meal frequency) is the most important component of over-consumption, modifications to food structure that specifically limit meal size may be more effective than manipulations that aim solely to reinforce inter-meal satiety. There is a clear need for more systematic analyses of fibre action, with standardised methodology, to identify fibres that can normalise eating rates and fullness when incorporated into foods - enabling individuals to establish healthier eating styles. The studentship examines fibre actions on the development of intra-meal satiation and the strength of post-meal satiety. The experiments will incorporate Universal Eating Monitor apparatus for continuous real-time measurement of eating. MATERIALS: The research will exploit the particular properties of different fibres (Resistant Starches and Fructo-oligosaccharides) to explore their appetite suppressant efficacy, and specific modes of action (in terms of behavioural, psychological, physiological and metabolic consequences). To achieve these aims, we will incorporate fibre as a meal ingredient and measure real time changes in satiation and satiety. This method will permit 1) the direct measures of the specific consequences of eating a meal; 2) identify fibres that most effectively reduce appetite, and 3) elucidated their temporal locus and mode of action through measures of specific biomarkers. These studies will have direct implications for both understanding the psychological/biological mediation of satiation and satiety, and the development of satisfying, filling foods that might aid weight loss by the prevention of over-consumption. OUTCOME: We will determine optimal appetite-suppressant doses of fibres, and assess their effects on: intake; intra-meal eating, sensory and appetite measures; post-meal satiety and compensatory intake; appetite-related gastrointestinal peptide activity (ghrelin, GIP, GLP-1 & PYY); specific markers for oro-caecal transit (C13/H2); blood glucose, insulin and FFA; and indices of colonic fermentation and gut microbiota modification. In addition to acute laboratory studies, we will assess the long-term (28 d) impact of fibre enrichment on each biomarker.